Publications

• Sundgot-Borgen, Christine; Daus, Stephan; Fandrem, Hildegunn; Pedersen, Cathrine; Besche, Torstein de & Vestad, Lene [Show all 36 contributors for this article] (2026). Multilevel implementation assessment of a national health and life skills curriculum policy: development and content validation. Research Square. ISSN 2693-5015. doi: 10.21203/rs.3.rs-11061256/v1. Full text in Research Archive Show summary

  Abstract Background Curriculum policies addressing health and life skills pose challenges for implementation research because implementation depends on local interpretation and professional judgement rather than uniform content, dosage, or delivery. Existing implementation measures, often developed for standardised interventions, may therefore be poorly suited to capturing how such policies are interpreted and enacted across school-system levels. This study describes the development and content validation of the Health and Life Skills Implementation Assessment (HLS-IA), designed to assess a nationwide curriculum policy across school-owner, school-leader, teacher, and classroom-practice levels. Methods Development combined implementation frameworks and reviews of existing measures with stakeholder involvement, two expert workshops, 17 cognitive interviews, and technical and quantitative pilot testing. These iterative procedures examined the relevance, comprehensibility, applicability, and practical feasibility of the questionnaires and informed successive revisions. Results The development process resulted in four coordinated HLS-IA questionnaires addressing implementation determinants, processes, and outcomes. The questionnaire targeting classroom practice is administered repeatedly as a lesson-based teacher log and distinguishes planned from enacted practice. Stakeholder involvement shaped both the implementation domains prioritised for assessment and the contextual framing of individual items. Expert appraisal, cognitive interviews, and pilot testing identified problems concerning redundancy, school terminology, interpretation, applicability, response options, and questionnaire routing, leading to the removal, reformulation, and refinement of items and response formats. The first national application in 2025 included responses from approximately 458 schools, demonstrating the practical feasibility of coordinated multilevel data collection while also highlighting recruitment challenges. Conclusions Developed through content-validation procedures, the HLS-IA provides a basis for examining how organisational and contextual conditions shape the local enactment of health- and life-skills-related aims in schools and for subsequent psychometric evaluation. The study also offers transferable methodological guidance for assessing complex health-promoting policies implemented through existing public institutions, particularly when professional judgement, local adaptation, and coordination across system levels are integral to implementation.

• Carson, Alexis Christine; Zidan, Mahmoud; Olstad, Emilie Willoch; Gervin, Kristina; Galesloot, Tessel E. & Scholte, Iris [Show all 9 contributors for this article] (2026). Genetically Informed Research Designs in Perinatal Pharmacoepidemiology: A Methodological Overview. Drug Safety. ISSN 0114-5916. 49(7), p. 761–773. doi: 10.1007/s40264-026-01647-9. Full text in Research Archive Show summary

  Despite the widespread use of medications during pregnancy, ethical and methodological barriers to clinical trials make observational studies necessary for evaluating medication safety in this population. Observational studies are prone to biases that often limit their validity due to the lack of randomization; integrating genetic information through discordant sibling designs, polygenic scores, and Mendelian randomization can address several confounding issues. However, application of these three approaches in perinatal pharmacoepidemiology has been limited. Complementing traditional designs with these genetically informed research designs can tackle common biases and strengthen causal inference. This paper focuses on applying genetically informed research designs to child outcomes in perinatal pharmacoepidemiology by reviewing various methods, discussing their strengths and limitations, and examining their application to date, as well as considerations for implementing them in future research. Such considerations include the availability of genetic data, the complexity of integrating genetic data with existing epidemiological data, and selection of appropriate genetic instruments for analyses. Incorporating causal inference in perinatal pharmacoepidemiology can ultimately contribute to enhancing safe medication use during pregnancy.

• Ystrom, Eivind (2026). Editorial: When children also shape the family environment. JCPP Advances. 6(2). doi: 10.1002/jcv2.70136. Full text in Research Archive Show summary

  Family research in child and adolescent mental health has often been framed as if influence runs mainly from adults to children. Bjørndal et al. provide a timely corrective. Using longitudinal network models that separate within‐person from between‐person associations, they show that adolescent mental health difficulties and family dynamics are interrelated over time, and that emotional symptoms may precede later hyperactivity/inattention and sibling problems. Their findings also point to reinforcing loops within the family system, particularly between low family support and negative feelings towards the family. This matters because family members are not merely environmental exposures; they are genetically correlated social environments, and children can shape parental and sibling dynamics as well as be shaped by them. Distinguishing between variables with stronger outgoing and ingoing influence may help refine which intervention hypotheses should be prioritized, and which should be discarded or treated more cautiously.

• Hoyos, Lucía de; Schlag, Fenja; Jahagirdar, Sanjeevan; Corfield, Elizabeth Claire; Allegrini, Andrea G. & Admiraal, Danielle [Show all 95 contributors for this article] (2026). Genome-wide analysis of social behaviour across social domains, reporters and developmental stages: a meta-regression approach. Nature Human Behaviour. doi: 10.1038/s41562-026-02551-z. Full text in Research Archive Show summary

  Social behaviour is a heritable trait linked to well-being and mental health, yet it varies across social context, including social domains, informants and development, which may shape its underlying genomic architecture. Here, we conducted a genome-wide meta-regression meta-analysis of social behaviour from infancy to early adulthood, studying ~500,000 repeated measures in European-ancestry cohorts ( N  = 73,321). We modelled heterogeneity in single-variant associations across social domains (low prosocial behaviour and peer/social difficulties), multiple informants (parents, teachers and self-reports) and ages (2–29 years), identifying 6 associated loci, including variation within CADM2 ( P  = 2.51 × 10 −9 ). Single nucleotide polymorphism-based heritability ranged from 2% to 7%, and the genetic architecture comprised 4 factors reflecting differences in either social domains or informants. Polygenic scores ( N  = 16,305) accurately predicted contextual variation in independent cohorts, with some cross-ancestry transferability. Context-specific patterns of genetic correlations, particularly when estimating the developmental onset of associations, offer opportunities to disentangle shared trajectories linking social behaviour with later-life and mental health outcomes.

• Peters, Kim; Jeftić, Alma; Ballard, Timothy; Zhou, Steven; Steffens, Niklas K. & Inceoglu, Ilke [Show all 379 contributors for this article] (2026). Think political leader — think he or she? A multi-country test of a gender-fair language intervention to reduce gendered leadership stereotypes. Leadership Quarterly. ISSN 1048-9843. 37(6), p. 101991–101991. doi: 10.1016/j.leaqua.2026.101991. Full text in Research Archive Show summary

  Women are greatly underrepresented in positions of political leadership around the world. In seeking to explain this underrepresentation, some researchers have pointed to people's tendencies to stereotype leaders as more similar to men than women as these tendencies can support the belief that women are unsuited to leadership. This project aimed to test whether a subtle linguistic intervention was able to ameliorate this gender bias in political leadership stereotypes across different languages and national contexts (country/region N = 42, language N = 30, sample N = 22,996). Specifically, this project examined whether gender-fair language (e.g., the use of paired pronouns ‘he or she’) can reduce the tendency for people to stereotype political leaders as more similar to men than women. To increase the rigor with which these stereotypes were measured, this project complemented the dominant ‘cheap talk’ measure of personal stereotype content with an incentivised community measure of this content. As expected, participants stereotyped political leaders as more similar to men than women; this pattern was stronger on the incentivised measure of community stereotypes. Unexpectedly, there was no evidence that paired pronouns reduced this bias (there was weak exploratory evidence that paired nouns increased participants' tendencies to stereotype political leaders as more similar to women). This project suggests that the ability of gender-fair language interventions to ameliorate gender bias in the political leadership domain may be limited.

• Vira, Emily Gabriela; Bjørndal, Ludvig Daae; Kjøbli, John; Røysamb, Espen; Helland, Siri Saugestad & Nes, Ragnhild Bang (2026). Automatic emotional responses as a transdiagnostic risk and emotional control as a protective factor for adolescent psychopathology: a network analysis. Scientific Reports. doi: 10.1038/s41598-026-60118-4. Full text in Research Archive Show summary

  Abstract Adolescence is a critical developmental period marked by heightened risk for emotion-related impulsivity (ERI), challenges in emotion regulation (ER), and mental health difficulties. Dual-process models propose that individuals respond to emotions either automatically or deliberately, with implications for mental health. We applied network analysis using a Gaussian Graphical Model to examine associations between automatic and deliberate emotional responses and symptoms of internalizing, externalizing, and thought problems in a general population of adolescents from south-east Norway ( N  = 918; Mage = 13.97, SD = 0.93, range = 12–18; 54.60% female). This cross-sectional study relied on self-report. Automatic ER and ERI nodes exhibited the most connections with symptom nodes across internalizing, externalizing, and thought problems. The strongest association linked limited access to ER strategies with feeling down and depressed. Deliberate ER nodes were also interconnected with symptoms, the strongest association showing more emotional control being linked to less feeling bad or not liking oneself. Several nodes demonstrated many or strong connections with other nodes within and across their groupings (i.e., strength and bridge centrality, respectively). Findings suggest that responding automatically may reflect a transdiagnostic risk factor and emotional control may serve as a protective factor, and these may be particularly useful targets in intervention and prevention efforts. Future studies are needed to determine causality.

• Bridger, Emma K.; Maltby, John; Fried, Eiko I.; Ebrahimi, Omid V. & Bjørndal, Ludvig Daae (2026). Linking psychological distress and multilevel socioeconomic disadvantage: A representative population-based study of 15,851 U.K. adults. American Psychologist. ISSN 0003-066X. doi: 10.1037/amp0001705. Full text in Research Archive
• Aksnes, Eira R.; Beck, Dani; MacSweeney, Niamh; Bos, Marieke G.N.; Ferschmann, Lia & Norbom, Linn B. [Show all 9 contributors for this article] (2026). Longitudinal associations between depressive symptoms and brain structure across late childhood and adolescence: A panel network analysis study. Biological Psychiatry: Global Open Science. p. 100824–100824. doi: 10.1016/j.bpsgos.2026.100824. Full text in Research Archive
• Crestol, Arielle; Meer, Dennis van der; Parker, Nadine; Lange, Ann-Marie G. de; Hagen, Espen & Oppenheimer, Hannah [Show all 12 contributors for this article] (2026). Sex differences in polygenic risk for sex-biased brain disorders: Associations with diagnostic status and brain age gap. Translational Psychiatry. doi: 10.1038/s41398-026-04220-1. Full text in Research Archive
• Kuper, Niclas; Gardiner, Gwendolyn; Baranski, Erica; Funder, David C.; Rauthmann, John F. & Project, Members of the International Situations (2026). Cultural differences in the Personality Triad: The interplay of personality traits, situation characteristics, and behavioral states around the world. Journal of Personality and Social Psychology. ISSN 0022-3514. 130(5), p. 1046–1046. doi: 10.1037/pspp0000581. Full text in Research Archive
• Kraft, Brage; MacSweeney, Niamh Anne; Page, Christian Magnus; Lyle, Robert; Tsotsi, Stella & Ulset, Vidar Sandsaunet [Show all 12 contributors for this article] (2026). The effect of prenatal maternal stress on adolescent internalizing symptoms and the genetic moderation of executive functioning and prefrontal cortex. Psychological Medicine. ISSN 0033-2917. 56. doi: 10.1017/S0033291726105431. Full text in Research Archive Show summary

  Background: Prenatal maternal stress is a known risk factor for later emotional problems, yet not all exposed offspring develop psychopathology. Executive functioning and prefrontal cortex structure and activity may buffer these effects, but it remains unclear whether genetic predis positions in these domains moderate associations with adolescent internalizing symptoms. Methods: We examined 3,111 adolescents (1,881 females, 1,230 males). Prenatal stress was measured via a cumulative index across four domains. Internalizing symptoms were self reported at ages 14 and 16. Genetic predisposition for executive functioning was indexed using a polygenic score (PGS) derived from adult samples, applied here to estimate genetic predis position for executive functioning in adolescence. We also estimated a prefrontal cortex PGS based on cortical thickness and activation in six prefrontal regions, with a composite index derived from the first principal axis summarizing these measures. Results: Higher prenatal stress was significantly associated with more internalizing symptoms in adolescence. Female sex and maternal genetic risk for internalizing symptoms were also associated with higher symptom levels. Neither genetic disposition for executive functioning nor prefrontal cortex moderated this association overall. However, a weak interaction emerged at age 16, indicating that a genetic disposition for higher executive functioning was associated with greater internalizing symptoms under high stress exposure. Conclusions: Prenatal maternal stress predicted increased adolescent internalizing symptoms, with limited evidence for moderation by genetic predisposition for executive functioning. Higher genetic potential for executive functioning may confer increased sensitivity to early stress under certain developmental conditions.

• Schwaba, Ted; Sullivan, Margaret L. Clapp; Akingbuwa, Wonuola A.; Ilves, Kerli; Tanksley, Peter T. & Williams, Camille M. [Show all 138 contributors for this article] (2026). Robust inference and correlates from genetic associations with personality. Nature. ISSN 0028-0836. doi: 10.1038/s41586-026-10992-9. Full text in Research Archive
• Corfield, Elizabeth Claire; Shadrin, Alexey; Frei, Oleksandr; Rahman, Mohammad Zillur; Akdeniz, Bayram Cevdet & Filiz, Tahir Tekin [Show all 29 contributors for this article] (2026). Family genetic designs in MoBa provide insights into health and functioning. Nature. ISSN 0028-0836. doi: 10.1038/s41586-026-10926-5. Full text in Research Archive Show summary

  Genome-wide association studies using large, population-based samples of unrelated individuals have discovered thousands of genetic associations with health and disease1. These studies can help explain genetic and environmental risks. However, increasing evidence suggests that population-based estimates, while precise, can also reflect confounding that affects their use and interpretation. This confounding can be overcome using data from genotyped family members, such as nuclear mother–father–child trios2,3. However, samples of genotyped families are rare4,5,6,7,8,9,10,11. Here we illustrate some of the advantages of familial data using the Norwegian Mother, Father and Child Cohort Study (MoBa), a population-based cohort of parents and offspring with extensive genotype data (n ≈ 230,000) (ref. 3), along with broad and longitudinal phenotyping of health and functioning. We provide an overview of MoBa and describe the quality control of genotype data tailored to this extensively related sample. We then use trio data to illustrate how family-based genomic designs can identify distinct direct and indirect sources of genetic influence and structural confounding. As examples, we analyse children’s height, educational achievement, depressive symptoms and sleep duration. These demonstrations highlight MoBa as a broadly valuable resource for advancing understanding of health and functioning across the lifecourse and generations.

• Poornikoo, Mehdi; Fang, Yuan; Sundgot-Borgen, Christine; Klomstén, Anne Torhild; Folstad, Siri Hausland & Edvoll, Maud [Show all 12 contributors for this article] (2026). The Effect of School Resources on Student Mental Health under the Norwegian Curriculum Reform. Open Science Framework (OSF). doi: 10.17605/OSF.IO/SCA53. Full text in Research Archive
• Edvoll, Maud Clemson; Poornikoo, Mehdi; Klomstén, Anne Torhild; Sundgot-Borgen, Christine; Ystrom, Eivind & Røysamb, Espen [Show all 11 contributors for this article] (2026). OSF Embargoed Preregistrering; A Norwegian School Reform: The Effects of ‘Health and Life Skills’ for the Socioemotional School Climate. Open Science Framework (OSF). doi: https:/osf.io/tfrqu/overview. Full text in Research Archive
• Barak, Eden Nordvold; Kolskår, Knut-Kristian; Dahl, Christine; Alnæs, Dag; Andreassen, Ole & Nærland, Terje [Show all 9 contributors for this article] (2026). Birth Weight and Neurodevelopmental Disorders Across Diagnostic Categories: A Registry-Based Case–Control Study in Clinically Ascertained Samples | Child Psychiatry & Human Development | Springer Nature Link. Child Psychiatry and Human Development. ISSN 0009-398X. doi: 10.1007/s10578-026-02090-8. Full text in Research Archive Show summary

  Increasing prevalence of neurodevelopmental disorders (NDDs) is a growing public health concern. Identifying early risk markers may facilitate earlier intervention and reduce long-term burden. Although birth weight has been widely studied in relation to NDDs, evidence from clinically ascertained samples with single and overlapping diagnoses remains limited. In this case-control study, we compared birth weight between clinically referred individuals with intellectual disability (ID), autism spectrum disorder (ASD), and attention-deficit/hyperactivity disorder (ADHD) from the Norwegian BUPgen registry (n = 720) and a population-based sample from the Norwegian Mother, Father and Child Cohort Study (MoBa) (n = 98,716). Perinatal data were obtained through linkage to the Medical Birth Registry of Norway. Associations were examined using logistic regression adjusted for gestational age, sex, and parental age. Additional analyses assessed interactions by sex and parental age, and birth weight categories. For each 100 g decrease in birth weight, odds significantly increased for the groups any NDD (one or more NDD diagnoses; OR = 1.04) and multiple diagnoses (two or more co-occurring NDDs; OR = 1.07). In diagnosis specific analyses, odds significantly increased for ID (OR = 1.15) and ASD (OR = 1.03). No interactions were observed. In categorical analyses, low birth weight was associated with higher odds of ID (OR = 8.27, p < 0.001), multiple diagnoses (OR = 4.96, p < 0.001), and any NDD (OR = 2.11, p = 0.002). No associations were observed for high birth weight. These findings support low birth weight as an early marker of neurodevelopmental vulnerability across NDD outcomes. Lower birth weight was associated with higher odds of ID, ASD, multiple diagnoses and any NDD, but not ADHD. Associations were strongest and most consistent for ID and comorbid presentations, indicating heterogeneity across diagnostic categories. Increased risk was primarily observed at low birth weight, with no associations for high birth weight. Findings support birth weight as an early marker of neurodevelopmental vulnerability in a clinically ascertained sample.

• Demange, Perline Aline Delle; Nivard, Michel G.; Torvik, Fartein Ask; Eilertsen, Espen Moen; Cheesman, Rosa Catherine Gillespie & Nordmo, Magnus [Show all 9 contributors for this article] (2026). No evidence of parental mental health influencing children’s academic achievement: a within-family study. European Child and Adolescent Psychiatry. ISSN 1018-8827. doi: 10.1007/s00787-026-03100-9. Full text in Research Archive Show summary

  Children of parents with psychopathology generally perform less well in school than their peers. Parental symptoms might not, however, account for their lower achievement, as other familial factors might contribute. To examine the role of parental symptoms, we analyse data from 9,000 families in the Norwegian Mother, Father, and Child Study (MoBa). Parents reported their symptoms of anxiety, depression, ADHD, eating disorders, and alcohol use disorder during pregnancy and during their child’s childhood. Children in 5th grade (aged 10) completed nationally-standardised tests of mathematics, reading comprehension, and English (as an additional language). Comparing children who are cousins (children-of-siblings design), we controlled for unmeasured factors shared among family members that confound the relationship between parental mental health and children’s academic achievement. We found small associations between greater parental symptoms and lower scores in reading and mathematics (− 0.060 ≤ β ≤ −0.013). However, these associations were no longer significant when comparing cousins whose parents differ in mental health. Results suggest that parental symptoms do not exert a direct, clinically meaningful effect on children’s academic achievement. Although non-significant, associations with parental symptoms measured close to the child’s academic test are less attenuated than those measured during pregnancy. Notably, comparison between the overall MoBa sample and the children-of-siblings samples suggests ascertainment differences that hinder strong generalisations. Our findings underscore the importance of quasi-experimental family designs in identifying modifiable targets in intergenerational health and education research. Supporting parental mental health is crucial but its direct effect on children’s achievement may be smaller than often thought.

• Liu, Jinrui; Vittersø, Joar; Teulings, Irene Johanna Elisabeth; Nes, Ragnhild Bang; Mayerhofer, Lilian Juliane Kozlowski & Røysamb, Espen (2026). Jingle all the way? Pleasant and energized positive affect show differential longitudinal relationships with life satisfaction and personality. Journal of Positive Psychology. ISSN 1743-9760. doi: 10.1080/17439760.2026.2701098. Full text in Research Archive Show summary

  Positive affect (PA) is operationalized differently across studies, leaving open whether distinct conceptualizations relate to subjective wellbeing (SWB) similarly over time. Although mainstream wellbeing theory treats PA and life satisfaction (LS) as components of a latent SWB factor, empirical findings on their causal relations remain inconsistent. This study examined whether pleasant versus energized PA show comparable longitudinal associations with LS using random-intercept cross-lagged panel models across nine waves from two national longitudinal datasets, PAIRFAM (N = 12,520) and LISS (N = 17,532). Both PA types showed consistent bidirectional associations with LS, but relationships were stronger for pleasant PA. Cross-lagged effects and time-specific residual correlations were approximately twice as large compared to energized PA. Pleasant and energized PA also differed in their associations with extraversion and neuroticism. These findings suggest that PA indicator choice affects SWB measure validity, with implications for positive psychology interventions targeting SWB.

• Bright, Joanna K.; Ahmadzadeh, Yasmin I.; Oginni, Olakunle; Viding, Essi; Leve, Leslie D. & Neiderhiser, Jenae M. [Show all 11 contributors for this article] (2026). Triangulating evidence for genetic and environmental components of associations between parental behaviours and aggressive behaviour in children. Nature Communications. 17(1). doi: 10.1038/s41467-026-75095-5. Full text in Research Archive Show summary

  Parenting behaviours are often linked to childhood aggression, but many studies fail to account for shared genetics or test directionality. Using family-based designs, we control for genetic confounding and examined bidirectional effects across two samples. First, we apply a children-of-twins/siblings design in the Norwegian Mother Father and Child Cohort Study which uses genetic relatedness between family members to separate genetic and environmental components of parent-child associations. Second, we use longitudinal models in the USA-based Early Growth and Development Study, an adoption sample where parents and child are not genetically related, enabling estimation of parent-child associations without genetic confounding. Across both studies, we find evidence for genetic and environmental transmission between parenting and child aggression. We show significant child-to-parent effects on inconsistent discipline in both samples. In the children-of-twins analysis, the association between positive parenting and child aggression is shown to be due to shared genetics, where no statistically significant association is observed in the adoption sample. These findings build on the growing body of literature showing genetic influences on both aggression and parenting behaviours, whilst underscoring the value of triangulation.

• Bond, Tom A.; McAdams, Tom A.; Warrington, Nicole Maree; Hannigan, Laurie; Eilertsen, Espen Moen & Ayorech, Ziada [Show all 12 contributors for this article] (2026). Parental body mass index and offspring childhood body size and eating behaviour: A structural equation modelling analysis in the Norwegian Mother, Father and Child Cohort Study. PLoS Medicine. ISSN 1549-1277. 23(6). doi: 10.1371/journal.pmed.1005094. Full text in Research Archive Show summary

  Background The intergenerational transmission of obesity-related traits could propagate an accelerating cycle of obesity, if parental adiposity causally influences offspring adiposity. The extent to which intergenerational obesity associations are due to such causal effects, as opposed to genetic confounding (inheritance), is unclear. We aimed to establish whether associations between parental peri-pregnancy body mass index (BMI) and offspring birth weight (BW), BMI until 8 years of age, and 8-year-old eating behaviour are due to genetic confounding. Methods and findings Data were from the Norwegian Mother, Father and Child Cohort Study, a prospective population-based birth cohort born between 1999 and 2009 at 50 out of 52 hospital maternity units in Norway. We compared the strength of the associations of maternal pre-pregnancy BMI versus paternal BMI during pregnancy, with offspring outcomes including birth weight and BMI assessed between age 6 months and 8 years of age, and appetite-related eating behaviour traits assessed at age 8 years via the Child Eating Behaviour Questionnaire (CEBQ), adjusting for potential confounders including parity, parental/grandparental language group and parental age, smoking, education and income). We then used an extended children of twins structural equation model (SEM) to quantify the extent to which associations were due to genetic confounding. Up to 85,866 children (51.3% male) were included in linear regression models, whereas SEM models included up to 50,999 children. Maternal BMI was more strongly associated than paternal BMI with offspring BW, but the maternal-paternal difference decreased for offspring BMI after birth. Greater parental BMI was associated with obesity-related offspring eating behaviours. SEM results indicated that genetic confounding did not explain the association between parental BMI and offspring BW, but explained the majority of the association with offspring BMI from 6 months onwards. For 8-year BMI, genetic confounding explained 79% (95% CI [62, 95]; p = 1.9 × 10−12) of the covariance with maternal BMI and 94% (95% CI [72, 113]; p = 2.7 × 10−14) of the covariance with paternal BMI. Limitations of this study include selective recruitment and attrition, potential bias due to parental assortative mating, and that findings may not generalise beyond high-income country settings with high obesity prevalence. Conclusions We found strong evidence that parent–child BMI associations may primarily be due to genetic confounding. When considered alongside prior evidence, this finding may argue against a strong causal effect of maternal or paternal adiposity on childhood adiposity via intrauterine or periconceptional mechanisms.

• Bjørndal, Ludvig Daae; Hegemann, Laura Elizabeth; Pettersen, Johanne Hagen; Corfield, Elizabeth Claire; Hannigan, Laurie & Yilmaz, Zeynep [Show all 14 contributors for this article] (2026). Investigating Relationships Between Genetic Risk, Childhood Maltreatment, and Eating Disorders in Women. Biological Psychiatry: Global Open Science. 6(5). doi: 10.1016/j.bpsgos.2026.100761. Full text in Research Archive Show summary

  Background Genetic and environmental factors contribute to eating disorder risk, yet their interplay is poorly understood. We examined whether childhood maltreatment and polygenic scores for anorexia nervosa (PGS-AN) and binge-eating broad (PGS-BEB) are associated with eating disorders. We also examined the interactions between childhood maltreatment and PGSs in predicting eating disorders. Methods This nested case-control study used data from up to 63,989 mothers in the MoBa (Norwegian Mother, Father and Child Cohort Study). Mothers reported on their own experiences of 4 childhood maltreatment types: long-term humiliation or degradation, threats to self or someone close, physical abuse, and sexual abuse. Diagnoses of AN, bulimia nervosa (BN), binge-eating disorder (BED), purging disorder (PD), and binge-eating spectrum disorders (BESP) were obtained using self-report data from 5 time points and population health registers. Results The prevalence of AN, BN, BED, PD, and BESP was 2.19%, 4.15%, 10.39%, 0.60%, and 12.96%, respectively. All childhood maltreatment types were strongly associated with elevated eating disorder likelihood (with odds ratios [ORs] ranging from 1.71 to 3.29) as were eating disorder PGSs (with ORs ranging from 1.05 to 1.31). There were no multiplicative interaction effects between childhood maltreatment and PGSs. Small additive interactions were observed between PGS-AN and PGS-BEB and degradation/humiliation for BN and BESP in exploratory analyses. Conclusions Eating disorder PGSs and childhood maltreatment are associated with higher odds of eating disorders. Furthermore, we found tentative evidence of small additive interaction effects between polygenic liability and childhood maltreatment, suggesting that their combined influence further elevates the risk of some eating disorders.

• Wechsler, Daniel L.; Eilertsen, Espen Moen; Ahmadzadeh, Yasmin I.; Cheesman, Rosa Catherine Gillespie; Adamo, Nicoletta & Hannigan, Laurie [Show all 8 contributors for this article] (2026). Direct and Indirect Genetic Effects on Child ADHD Traits in Early and Mid-Childhood: Trio Genome-Wide Complex Trait Analyses in a Large Norwegian Birth Registry Cohort. Behavior Genetics. ISSN 0001-8244. 56(4), p. 184–193. doi: 10.1007/s10519-026-10273-1. Full text in Research Archive Show summary

  Genetic variants in family members may exert environmentally mediated indirect genetic effects on children’s attention-deficit hyperactivity disorder (ADHD) traits. We set out to quantify the indirect genetic effects of parents’ genotypes on children’s ADHD traits as measured in early and mid-childhood. We analyzed data from genotyped trios of children, mothers, and fathers of European ancestry from the Norwegian Mother, Father and Child Cohort Study (MoBa) birth cohort. Child ADHD data were available for analytic subsamples of 12,374 trios at age 5 (children 50.5% male), and 12,714 trios at age 8 (children 50.9% male). We quantified direct genetic effects of children’s genotype and indirect effects of mothers’ and fathers’ genotypes on children’s ADHD traits at each age. Differing patterns of direct and indirect genetic effects were observed in early and mid-childhood, with predominantly maternal indirect genetic effects on ADHD traits at age 5, and roughly equal direct genetic effects and maternal indirect effects on ADHD traits at age 8. However, large standard errors hindered confident inference as to the relative importance of specific effects, and model fit comparisons ultimately favored models with no indirect genetic effects at age 5 and 8, as well as no direct genetic effects at age 5. We do not find clear evidence of indirect genetic effects of maternal or paternal genotype on child ADHD traits at ages 5 and 8, nor direct genetic effects on child ADHD traits at age 5. While previous findings of indirect genetic effects on ADHD subdomains at ages 3 and 8 broadly support the plausibility of indirect genetic effects operating on total ADHD scores at ages 5 and 8, it appears that indirect genetic effects on overall ADHD trait magnitude may be more difficult to estimate with precision than subdomain-specific effects.

• Sætren, Sjur Skjørshammer; Tjora, Tore; Tamnes, Christian Krog; Ferschmann, Lia; Hafstad, Gertrud Sofie & Augusti, Else-Marie (2026). Distinct Associations of Threat and Deprivation With Changes in Affective Control during Adolescence: A Longitudinal Population-Based Study. Developmental Science. ISSN 1363-755X. 29(5). doi: 10.1111/desc.70264. Full text in Research Archive
• Porneso, Ralph; Havdahl, Alexandra; Eilertsen, Espen Moen & Ystrom, Eivind (2026). Longitudinal genome-wide analysis reveals putative non-additive loci in trait development. Cell reports. 45(8). doi: 10.1016/j.celrep.2026.117840. Full text in Research Archive Show summary

  Complex traits emerge from reciprocal interactions among genotype, environment, and developmental processes. Yet, standard genetic models assume purely additive effects, potentially obscuring non-additive effects. Here, we introduce a longitudinal log-linear variance and genotype-by-time model to detect associations from within-individual variation departing from additivity, i.e., putative non-additive effects. Applied to early growth (infant length and BMI) and cognitive traits (math and reading) of 45,000 to 65,000 individuals, we report 76 lead putative non-additive loci that are enriched 16-fold for cis-regulatory interactions. Of the 76, 6 overlap prior interaction studies (anthropometric) and only 3 loci overlap prior genome-wide association study (GWAS) (cognitive). Accounting for scale effects and linkage disequilibrium (LD), we observe that additive effects are correlated with putative non-additive effects, i.e., “effect pleiotropy.” These results are consistent with non-additive genetic contribution to trait development, which may partly be absorbed by effects estimated under standard GWAS parameterization that assumes strict additivity.

• Rayner, Christopher; Hannigan, Laurie; Badini, Isabella; Demange, Perline Aline Delle; Ofstad, Sverre Berg & Ystrøm, Eivind [Show all 7 contributors for this article] (2026). Quantifying and adjusting for selection biases in the Norwegian Mother, Father and Child Cohort Study using population-wide individual-level registry information. International Journal of Epidemiology. ISSN 0300-5771. 55(4). doi: 10.1093/ije/dyag122. Full text in Research Archive Show summary

  Background Selective participation in research studies hampers researchers’ ability to draw valid and generalizable inferences from analyses. Quantifying and adjusting for selective participation are desirable but can be challenging given the paucity of data for non-participants. Methods We used individual-level information from population registers to predict baseline and continued participation in the Norwegian Mother, Father and Child Cohort Study (MoBa). Inverse probability weights were computed from logistic regression models with elastic-net regularization. We predicted selective participation and attrition in 296 987 mothers, of whom 29% returned the first MoBa questionnaire and 12.5% returned a follow-up questionnaire 8 years later. To quantify bias, we computed sample characteristics and exposure–outcome associations in the target population and stratified samples. To compare approaches for adjusting for bias, we computed weighted sample estimates by using three sets of weights. Results Unweighted sample estimates were systematically different from target-population values, indicating bias due to selective participation. Baseline participation weights substantially reduced the impact of selection bias on mean values by 93% and associations by 75%. Attrition weights reduced attrition bias on mean values by 78% and associations by 50% but were less effective for reducing participation bias (22% and 14% respectively). Conclusion In this sample, characteristics and effect estimates are substantially different from target-population values. Participation weights were relatively effective at reducing bias due to selective participation but attrition weights were not. Estimates from studies that use attrition weights may still contain non-negligible selection bias—particularly if the baseline sample is not representative of the target population. Future studies should prioritize opportunities for deriving sampling weights for participation as well as attrition.

• Beck, Dani; Carrick, Chloe; Aksnes, Eira Ranheim; MacSweeney, Niamh Anne; Westlye, Lars Tjelta & Fuhrmann, Delia [Show all 7 contributors for this article] (2026). Synchrony between brain age and internalising and externalising symptoms across adolescence. Communications Biology. doi: 10.1038/s42003-026-10722-x. Full text in Research Archive Show summary

  Abstract Adolescence is a period of rapid neurobiological and behavioural change, yet how brain maturation deviations relate to psychopathology remains unclear. Here, we show, using data from the Adolescent Brain Cognitive Development Study, that deviations in brain age are coupled with internalising and externalising symptom development across adolescence. Combining multimodal brain age prediction across four waves (ages ~8.3–17.5) with bivariate latent growth curve models of ten symptom waves, we found coordinated nonlinear development between brain maturation and symptoms: adolescents whose brains increasingly diverged from age-expected maturation showed increasing symptoms. Effects were most consistent for internalising symptoms in females ( r  = 0.15–0.23) and broader for externalising symptoms in both sexes ( r  = 0.15–0.32); intercept-level associations were weaker ( r  = 0.08–0.09). Sex differences were not robust after correction. Vulnerability to adolescent psychopathology appears more closely linked to changes in brain maturational tempo than to fixed differences in brain age.

• Bø, Simen & Fluit, Sam (2026). Psykisk helse, partnere og politikk. Tidsskrift for Norsk psykologforening (Psykologtidsskriftet). ISSN 0332-6470. Full text in Research Archive Show summary

  Sam Fluit har forsket på sammenhengen mellom psykisk helse, selvtillit og politiske holdninger, og om partneres politiske preferanser samme…

• Potočár, Libor; Alonso, Laura Cachón; Kozák, Michal; Rodríguez-Cano, Rubén; Formánek, Tomáš & Soest, Tilmann von (2026). The dynamic interplay between loneliness and health behaviors from adolescence to midlife: A Norwegian population-based cohort study. Psychological Medicine. ISSN 0033-2917. 56. doi: 10.1017/s0033291726105029. Full text in Research Archive Show summary

  Background Adverse health behaviors, such as physical inactivity and smoking, constitute a potential pathway connecting loneliness to poor mental and physical health. No prior study has investigated the dynamic interplay between loneliness and a broad range of health behaviors across the first half of life. Methods We used data from a Norwegian population-based cohort study (n = 3,072) spanning 28 years from adolescence to midlife. Applying a propensity score-based causal inference approach, we examined bidirectional prospective associations between loneliness and health behaviors, comprising alcohol use, body mass index (BMI), smoking, and physical exercise. Results Loneliness in adolescence was associated with lowered physical exercise (mean difference: −14.13 minutes/week, 95% CI: −26.54 to −1.72), and loneliness during young adulthood was linked to increased BMI (0.37 points, 0.12–0.63). In the reverse direction, moderate alcohol use (−0.07 SD, −0.13 to −0.01 and − 0.19 SD, −0.33 to −0.05), smoking (−0.12 SD, −0.23 to −0.01), and moderate physical exercise (−0.16 SD, −0.26 to −0.07 and − 0.07 SD, −0.14 to −0.01) during adolescence and emerging adulthood were linked to reduced loneliness. All other associations were consistent with a null effect. Conclusions Our results provide limited support for the causal effects of loneliness on health behaviors across the first half of life. By contrast, findings in the reverse direction suggest that health behaviors in young people – whether health-promoting or risky – are socially embedded and may facilitate socializing. To tackle youth loneliness, public health policies should promote equitable access to health-promoting behaviors.

• Fluit, Sam; Bierwiaczonek, Kinga; Kunst, Jonas R. & Soest, Tilmann von (2026). The mental health–politics nexus: How mental health trajectories from adolescence to midlife shape political attitudes and voting patterns. Political Psychology. ISSN 0162-895X. 47(4). doi: 10.1111/pops.70178. Full text in Research Archive Show summary

  Abstract With political polarization increasing, it is important to understand the development of political preferences. Previously, adolescent mental health problems have been linked to lower adulthood voting rates, while relationships between life trajectories of mental health and political attitudes and orientations remain largely underexplored. Using longitudinal data from the population‐based cohort Young in Norway ( N  = 2215) spanning three decades, we examine associations between adolescent internalizing (depression, anxiety symptoms) and externalizing problems and 12 midlife political preferences. Latent class growth analysis identified three trajectories for internalizing and two for externalizing problems. Elevated levels of either problem type demonstrated significant associations with lower political and social trust in midlife. Elevated initial internalizing problems, regardless of subsequent development, were related to more left‐wing profiles. Conversely, persistently elevated externalizing problems showed associations with stronger right‐wing profiles. These findings demonstrate that mental health trajectories from adolescence into adulthood are systematically related to distinct political preferences in midlife.

• Beck, Dani; Westlye, Lars Tjelta & Tamnes, Christian Krog (2026). Cardiometabolic Risk and Structural Brain Development in a Large Community-Based US Cohort. Human Brain Mapping. ISSN 1065-9471. 47(8). doi: 10.1002/hbm.70575. Full text in Research Archive
• Krätschmer, Ilse; Hegemann, Laura Elizabeth; Hofmeister, Robin J.; Corfield, Elizabeth Claire; Mahmoudi, Mahdi & Delaneau, Olivier [Show all 14 contributors for this article] (2026). Separating direct, indirect, and parent-of-origin genetic effects in the human population. Cell Genomics. 6(7). doi: 10.1016/j.xgen.2026.101277. Full text in Research Archive Show summary

  We introduce JODIE, a genetic joint modeling approach that estimates how DNA loci influence human traits by partitioning genetic effects into four components: direct effects (from a child’s alleles), indirect maternal and paternal effects (from parents’ alleles), and parent-of-origin (PofO) effects (dependent on parental transmission of alleles), while uniquely accounting for assortative mating. We analyze 30,000 child-mother-father trios from the Estonian Biobank and the Norwegian Mother, Father, and Child Cohort, focusing on height, body mass index, and childhood educational test scores. We find direct effects to be the largest contributor to trait variation, but combined, indirect parental and PofO effects are similarly substantial. We support our results by within-family genome-wide association testing and identify 276 independently associated DNA regions with a complex interplay between direct, indirect, and PofO effects. By joint modeling, we show that direct, indirect, and PofO effects collectively shape human phenotypic variation across loci genome-wide.

• Bernardoni, Fabio; Arold, Dominic; Schoppik, Luis; Bahnsen, Klaas; Ge, Ruiyang & Moreau, Clara [Show all 36 contributors for this article] (2026). Brain morphology in Anorexia Nervosa and its subtypes: A multi-cohort study of individual participant data. PLoS Medicine. ISSN 1549-1277. 23(5), p. e1004809–e1004809. doi: 10.1371/journal.pmed.1004809. Full text in Research Archive
• Sørensen, Lin; Hjo, Emy Camille Cornelia; Vollsund, Anna Elfrida Hovde; Flo-Groeneboom, Elisabeth; Jensen, Daniel Andre & Tømmeraas, Ane Martine [Show all 11 contributors for this article] (2026). Emotion regulation difficulties in adults with ADHD and associations with insomnia symptoms. Journal of Affective Disorders. ISSN 0165-0327. 411. doi: 10.1016/j.jad.2026.121941. Full text in Research Archive Show summary

  Objectives: Adults with attention-deficit/hyperactivity disorder (ADHD) frequently experience both emotion regulation difficulties and sleep disturbances. Although theories of insomnia and studies in non-ADHD samples suggest a link between poor emotion regulation and insomnia, this relationship is understudied in ADHD. We examined whether difficulties regulating emotions were associated with insomnia symptoms in adults with ADHD, and whether this association was moderated by gender, age (<30 or ≥30 years), or eveningness preference. Methods: A cross-sectional online survey was distributed in collaboration with the Norwegian ADHD Association. Of 1541 respondents, 1414 adults with self-reported ADHD diagnosis (81% female; ages 16–74; years, M age = 40 years) met inclusion criteria. Participants completed measures of emotion regulation, insomnia symptoms, chronotype, and sociodemographic and clinical characteristics, including education level, occupational status, ADHD symptoms, depression, anxiety, substance use, medication use, and comorbid conditions. Results: Multiple linear regression analyses showed that greater emotion regulation difficulties, especially limited access to effective regulation strategies, were associated with more insomnia symptoms. Associations remained significant after controlling for sociodemographic and clinical characteristics. The association between emotion regulation difficulties and more insomnia symptoms was stronger (medium effects) among emerging adults (<30 years) than older adults (small effects). No moderation effects were found for gender, age as a continuous moderator, or eveningness preference. Conclusions: Difficulties in adaptively regulating emotional states, a common challenge in ADHD, were linked to more insomnia symptoms. These findings underscore the importance of assessing and addressing sleep disturbances in adults with ADHD, particularly among those with emotion regulation difficulties.

• Edvoll, Maud Clemson; Folstad, Siri Hausland; Eftedal, Nikolai Haahjem; Poornikoo, Mehdi; Fang, Yuan & Ystrøm, Eivind [Show all 11 contributors for this article] (2026). A Norwegian curriculum reform: Effects for 10th graders’ academic performance. Studies in Educational Evaluation. ISSN 0191-491X. 89. doi: 10.1016/j.stueduc.2026.101616. Full text in Research Archive
• Brieant, Alexis; Chaku, Natasha; Beck, Dani; MacSweeney, Niamh Anne; Rakesh, Divyangana & Tamnes, Christian Krog (2026). Timing and tempo of puberty and neurodevelopment following adversity: A registered report. Developmental Cognitive Neuroscience. ISSN 1878-9293. 79. doi: 10.1016/j.dcn.2026.101738. Full text in Research Archive
• Yang, Xi; Agartz, Ingrid; Andreassen, Ole; Bachman, Peter; Baeza, Inmaculada & Bartholomeusz, Cali [Show all 78 contributors for this article] (2026). Local chemoarchitecture explains widespread lower cortical thickness associated with clinical high risk for psychosis. Molecular Psychiatry. ISSN 1359-4184. doi: 10.1038/s41380-026-03586-4. Full text in Research Archive Show summary

  The Clinical High Risk (CHR) state for psychosis is consistently associated with widespread cortical thinning. However, the underlying mechanisms driving this neuroanatomical phenotype remain poorly understood. Here, we integrated the ENIGMA CHR Working Group’s large pooled dataset (N = 1782 CHR, N = 1333 healthy controls) with an open-source PET molecular atlas to identify, for the first time, potential neurochemical drivers of cortical thinning associated with psychosis risk, transition, and its core symptoms. Using multilinear model analysis, we show that local chemoarchitecture significantly explains CT differences associated with CHR case-control status, the severity of negative symptoms, and future psychosis transition after excluding medication confounds. PET-based maps of dopamine, GABA, glutamate, serotonin, and norepinephrine consistently emerged as the strongest predictors of lower CT in CHR and psychosis transition (total dominance range: 62–69% and 58–87%, respectively), with contributions of monoamine systems being especially sensitive to medication exposure (8–23% change in dominance range). Negative symptom-associated cortical thinning was best explained by PET-based maps of dopamine, histamine, serotonin and opioid systems (total dominance range: 60–81%), with contributions of histamine being sensitive to medication exposure (9–19% change in dominance range). Combined, these results uniquely identify specific neurochemical systems – particularly monoaminergic, glutamatergic, and GABAergic pathways – as key molecular mechanisms associated with cortical thinning in people at high risk of developing psychosis.

• Liu, Jinrui; Nes, Ragnhild Bang; Vittersø, Joar; Teulings, Irene Johanna Elisabeth & Røysamb, Espen (2026). Positively Negative: Why Negative Affect is Linked to Higher Wellbeing. Journal of Happiness Studies. ISSN 1389-4978. 27(5). doi: 10.1007/s10902-026-01040-4. Full text in Research Archive Show summary

  Many researchers oppose the hedonic idea that wellbeing can be reduced to the maximization of positive affect (PA) and the minimization of negative affect (NA). However, few studies have investigated alternative optimal levels of affects other than maximized PA and minimized NA. This paper examines ideal levels of PA and NA, and their alignment as an alternative approach to wellbeing. Study 1 investigates people’s ideal levels of affects. In a randomized forced-choice experiment (N = 352, U.S.-based), most participants rejected a life without NA and idealized experiencing 10-13% NA and 66-80% PA across experimental conditions and two selfreported measures. Study 2 (N = 638, international sample) examines whether life satisfaction corresponds more closely to affective alignment than to affective maximization. Using piecewise regression, we found that PA was consistently and positively associated with life satisfaction. Lower NA was associated with higher life satisfaction only among those experiencing more NA than desired. For those already below their ideal NA level, further reduction was no longer related to life satisfaction. Crucially, participants whose experienced and ideal affects were aligned reported the highest life satisfaction, instead of the group with highest hedonic experience. Overall, our findings suggest that individuals feel most satisfied when their experience aligns with their ideal, rather than when maximizing hedonic experience. Furthermore, the alignment is more linked to life satisfaction than to wisdom or personal growth. All in all, maximizing PA and minimizing NA are neither desired nor associated with the highest life satisfaction.

• Ferschmann, Lia; Dobbelaar, Simone; Tamnes, Christian Krog; Tsotsi, Stella; Toenders, Yara Jo & MacSweeney, Niamh Anne (2026). Longitudinal Associations Between Pubertal Development and Youth Behavioral Adjustment in the Context of Parent and Peer Relationships. Social Development. ISSN 0961-205X. 35(3). doi: 10.1111/sode.70068. Full text in Research Archive
• Schubert, Henrik Alexander; Spoorenberg, Thomas; Dudel, Christian & Skirbekk, Vegard Fykse (2026). Masculinization of populations reverses sex differences in fertility. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 123(17). doi: 10.1073/pnas.2533317123. Full text in Research Archive
• Widding-Havnerås, Tarjei; Demange, Perline Aline Delle; Zachrisson, Henrik Daae; Borgen, Nicolai; Ystrøm, Eivind & Elwert, Felix (2026). Estimating returns to education using the genetic lottery. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 123(15), p. 1–10. doi: 10.1073/pnas.2537049123. Full text in Research Archive Show summary

  Does more schooling cause higher lifetime earnings? Social scientists have long sought to determine the economic returns to schooling given its importance to individual life chances and public policy. Prior estimates are limited by unobserved confounding in observational studies and the focus of popular quasi-experimental studies on increases in schooling at only one particular age. Genotyped data offer an opportunity to address unobserved confounding and to estimate the returns to an additional year of schooling at any age by using quasi-randomly assigned genetic variants related to education as instrumental variables [Mendelian randomization (MR)]. We analyze comprehensive Norwegian population registries with career-long earnings data and genotyped data from the Norwegian Mother, Father and Child Cohort Study (MoBa). We employ three identification strategies for triangulation: ordinary least squares (OLS) with covariate-adjustment, sibling and twin fixed-effects models, and MR. Estimated returns to schooling are 8.0% in MR (N = 109,800) and 6.3% in sibling-MR (N = 18,666). Extensive sensitivity analyses suggest that MR results are robust even to large potential violations of MR assumptions, including pleiotropy. MR estimates somewhat higher returns than OLS for the full population (5.9%, N = 1,255,604) and fixed-effects models for siblings (5.3%, N = 966,976) or monozygotic twins (3.2%, N = 2,630). The estimated internal rate of return to schooling exceeds opportunity costs of education as proxied by the market interest rate. The lifetime returns to schooling are positive and substantial across all models.

• Chegeni, Razieh; Nes, Ragnhild Bang; Cheesman, Rosa Catherine Gillespie; Ayorech, Ziada; Ystrøm, Eivind & Røysamb, Espen (2026). Direct and indirect parental genetic effects on offspring susceptibility to internalizing problems across development. Nature Mental Health. 4, p. 754–765. doi: 10.1038/s44220-026-00619-3. Full text in Research Archive Show summary

  Internalizing problems, including symptoms of anxiety and depression, are common in childhood and adolescence and are linked to adverse long-term outcomes. Although both child genetic variants and parental genetic influences contribute to these problems, the specific direct (child) and indirect (parental) genetic pathways involved remain unclear. We applied multi-polygenic score models using elastic net regression to identify key genetic predictors of depressive and anxiety symptoms at ages 8 and 14 in 9,314 parent–child trios from the Norwegian Mother, Father and Child Cohort Study. We included 90 polygenic scores (PGSs) for the trio, along with their respective interaction terms. Predictive accuracy improved with age, with models explaining up to 2.7% of the variance in depression and 1.2% in anxiety. Key predictors included child attention deficit hyperactivity disorder, cognitive skills and well-being spectrum PGSs; maternal PGSs for smoking and cognitive skills; and paternal well-being spectrum PGSs. These findings underscore the value of incorporating diverse parental genetic traits to understand intergenerational risk transmission and developmental changes in child mental health.

• Gurholt, Tiril Pedersen; Beck, Dani; Voldsbekk, Irene; Parker, Nadine; Askeland-Gjerde, Daniel E. & Lange, Ann-Marie Glasø de [Show all 13 contributors for this article] (2026). Linking obesity with white matter microstructure highlights the importance of brainstem tracts and sex differences. Brain Communications. 8(1), p. 1–15. doi: 10.1093/braincomms/fcag026. Full text in Research Archive Show summary

  While obesity (body mass index ≥ 30) has been consistently associated with white matter diffusion magnetic resonance imaging (MRI) phenotypes, the contributions of common obesity phenotypes on various diffusion metrics, and the moderating effects of sex and age, require further clarification. This study aims to elucidate these body–brain connections to enhance our understanding of the comorbid link between obesity and body anthropometrics and the brain using a large-scale dataset. We analysed cross-sectional data from 40 040 participants from the UK Biobank (52.2% female; ages 44–83 years) using multiple linear regression to evaluate how obesity and body anthropometrics relate to regional white matter diffusion tensor imaging metrics (fractional anisotropy, axial diffusivity, radial diffusivity, mean diffusivity). We also examined interactions with age and sex. Our analyses revealed significant associations between individual obesity phenotypes (i.e. obesity and body anthropometrics) and diffusion tensor imaging metrics of small effects, with partial correlation coefficient |r| effect sizes ranging from 0.02 to 0.20 for most regions of interest with largest effects in brainstem tracts. We observed more widespread sex-by-obesity phenotypes than age-by-obesity phenotypes interaction effects on diffusion tensor imaging metrics. Our results link obesity and body anthropometrics with white matter phenotypes and suggests that shared body fat-related pathways link physical and brain health that may vary based on sex and age. Understanding these body–brain relationships, and the role of age and sex, could enhance the development and evaluation of targeted, personalized, treatment strategies for brain disorders that co-occur with obesity, although further longitudinal and intervention studies are needed to map the causal dynamics of these associations.

• Ofstad, Sverre Berg; Tan, Tony & Andersson, Björn (2026). Comparing the difficulty of elective subjects in high school using a population-based Norwegian registry. Scandinavian Journal of Educational Research. ISSN 0031-3831. doi: 10.1080/00313831.2026.2648976. Full text in Research Archive Show summary

  When grade point averages (GPAs) are used for admission into tertiary education, there is an implicit assumption that any two identical GPAs convey the same level of academic competency. However, this assumption does not hold when students are free to choose elective subjects and there are differences in their difficulty and dimensionality. In this study, we utilized item response theory to examine dimensionality and difficulty of 11 elective subjects in Norwegian high school, while accounting for self-selection bias, using data from 21,666 third year students. Our results show that the GPA is best represented as a multidimensional construct. Additionally, we demonstrate that the selection bias in observed subject grade averages for electives conceals considerable differences in difficulty levels. Hence, the GPA of Norwegian high school students does not only reflect academic competency but also the decisions made regarding which elective subjects to take.

• Pettersen, Johanne Hagen; Eilertsen, Espen Moen; Hegemann, Laura Elizabeth; Hannigan, Laurie; Lund, Ingunn Olea & Johannessen, Pia Myklebust [Show all 12 contributors for this article] (2026). Intra-familial dynamics of mental distress during the Covid-19 lockdown. Translational Psychiatry. 16(1), p. 1–9. doi: 10.1038/s41398-026-03876-z. Full text in Research Archive Show summary

  Lockdowns and social restrictions imposed in response to the Covid-19 pandemic intensified the proximity and reciprocal exposure among members of nuclear families. It is unclear how variation in mental distress during this period is attributed to potential influences of family members. This study used genetic data from adolescents (n = 4 388), mothers (n = 27 852) and fathers (n = 25 953), to disentangle the contributions of parent-driven, child-driven, and partner-driven components to mental distress during the first two months of the Covid-19 lockdown. Separate models also included adolescents’ non-pandemic mental distress as outcomes (n = 13 484). Trio genome-wide complex trait analyses separated two types of genetic components; direct–how an individual’s genotype is associated with their own mental distress, and indirect–how an individual’s genotype is associated with the mental distress of family members. A trio polygenic score (PGS) design was used to investigate associations of specific genetic liability factors with mental distress, and whether these changed over time (PGS×time). Results suggest that family-level genetic factors contribute to mental distress; variance components capturing indirect genetic effects accounted for 10% of adolescent mental distress (mother-driven), 2–3% of maternal (partner-driven), and 5% of paternal mental distress (child-driven). Mothers’ depression and ADHD PGS were positively associated with fathers’ mental distress. No PGS×time interactions were found. Direct genetic effects accounted for 9–10% variance in mental distress across family members, partly explained by genetic variants associated with anxiety, depression, ADHD and neuroticism. These findings highlight the importance of family dynamics and emphasize the potential value of including family members in mental health interventions.

• Karl, Valerie; Bjørndal, Ludvig Daae; Aksnes, Eira Ranheim; Teulings, Irene Johanna Elisabeth; MacSweeney, Niamh Anne & Beck, Dani [Show all 9 contributors for this article] (2026). Symptom-specific links between internalizing problems and functional connectivity in adolescents: a network analysis. European Child and Adolescent Psychiatry. ISSN 1018-8827. doi: 10.1007/s00787-026-02989-6. Full text in Research Archive
• Bøen, Rune; Ørbeck, Beate; Hansen, Berit Hjelde; Skirbekk, Anne Benedicte; Kristensen, Hanne & Tamnes, Christian Krog [Show all 7 contributors for this article] (2026). Characterizing Attention and Cognitive Control Profiles of Children With ADHD and Anxiety. Journal of Attention Disorders. ISSN 1087-0547. doi: 10.1177/10870547261430076. Full text in Research Archive
• Teulings, Irene Johanna Elisabeth; Deserno, Marie K.; Liu, Jinrui; Nes, Ragnhild Bang; Røysamb, Espen & Vittersø, Joar [Show all 7 contributors for this article] (2026). Beyond the borders of wellbeing: network analyses reveal the fuzzy boundaries between wellbeing domains. Journal of Positive Psychology. ISSN 1743-9760. doi: 10.1080/17439760.2026.2651077. Full text in Research Archive Show summary

  Understanding what constitutes a good life is central to psychological research, yet wellbeing models remain contested with respect to their structure and borders. We employ a network approach to investigate how wellbeing dimensions interrelate and whether they form distinct or overlapping constructs. Using a large, population-based sample from the European Social Survey (N = 45,122; 29 countries), we identified strong links between a broad range of wellbeing indicators across different theoretical domains. Community detection revealed six empirical clusters that partially align with existing distinctions (e.g. hedonic versus eudaimonic wellbeing). However, we also identified 11 indicators belonging to multiple clusters, demonstrating the fuzzy boundaries between wellbeing domains. These results highlight the need for integrative frameworks that better capture the interconnected nature of wellbeing. Our findings encourage more granular analyses and underscore the need for comprehensive measurement tools to advance wellbeing research, inform policy, and guide public health efforts.

• Qin, Qi; Cheesman, Rosa Catherine Gillespie; Eilertsen, Espen Moen & Ystrom, Eivind (2026). Children's psychological traits and educational performance: How schools and residential areas moderate how individual traits translate into academic outcomes. JCPP Advances. p. 1–15. doi: 10.1002/jcv2.70100. Full text in Research Archive Show summary

  Abstract Background The extent to which children's psychological traits influence their educational performance is thought to depend on the fit between the individual and their developmental context. However, this assumption has yet to be empirically tested on a population scale. This study examines how neurodevelopmental, mental health, and personality traits interact with latent environmental contexts to enhance, maintain, or mitigate their educational performance. Methods Using the Norwegian Mother, Father and Child Cohort Study (MoBa), we estimated the association between 16 developmental traits and grade point average (GPA) in 26,875 children across environmental contexts in 2131 primary schools, 1075 middle schools, ~14,000 neighborhoods, 1471 districts, and 347 municipalities. Results Across the developmental traits, the effect on GPA ranged from −0.286 to 0.220. However, these effects varied substantially across environmental contexts (SD 0.022 to 0.090). Trait‐by‐context interactions were detected in primary schools (2 traits), middle schools (6 traits), neigbourhoods (0 traits), districts (3 traits), and municipalities (1 trait), respectively. Moderation magnitudes were largest for neurodevelopmental traits in primary schools. On average, the effects of ADHD and communication difficulties were −0.252 and −0.193. However, these effects differed substantially across primary schools with SD 0.090 and 0.070, implying b  < −0.370 and b  < −0.282 in 10% of schools. For average children, primary schools explained 0.504% of middle school GPA. Similarly, the effect of depression and extraversion was dependent on middle‐school environments ( b  = −0.128; SD = 0.058 and b  = 0.024; SD = 0.022). Moreover, schools and districts with high GPAs tended to express lower detrimental effects on children's developmental traits. Conclusion Schools and residential areas function as educational catalysts, enhancing or mitigating the influence of developmental traits. High‐performing environments compensate for psychological challenges, whereas lower‐performing contexts exacerbate difficulties. Because the study integrated multiple traits and contextual levels, the analyses were exploratory and data‐driven, and the findings should be interpreted as hypothesis‐generating. These results suggest a need for both context‐sensitive and individually tailored educational interventions.

• Valstad, Mathias; Eilertsen, Espen Moen; Ayorech, Ziada; Cheesman, Rosa Catherine Gillespie; Demange, Perline Aline Delle & Eftedal, Nikolai Haahjem [Show all 8 contributors for this article] (2026). Indirect genetic effects of siblings. Journal of Child Psychology and Psychiatry. ISSN 0021-9630. doi: 10.1111/jcpp.70130. Full text in Research Archive Show summary

  Background Within-family designs are increasingly used to decompose genotype–trait associations into direct and indirect genetic effects. Many such designs, including trio designs or within-sibship designs, assume an absence of sibling indirect genetic effects. Methods We expand two well-known molecular genetic within-family designs, one variance component (genome-based restricted maximum likelihood) and one trait-based (structural equation modeling with polygenic indices), to estimate sibling indirect genetic effects, along with direct genetic effects. We link the Norwegian Mother, Father, and Child Cohort Study (MoBa) to Norway's national education database to model genetic effects on national standardized testing results at ages 10, 13, and 14, and on parent-rated attention-deficit hyperactivity disorder (ADHD) symptoms at ages 3 and 8 in up to 15,971 genotyped and phenotyped siblings. Results Estimates of direct and indirect genetic effects from the genome-based restricted maximum likelihood and the structural equation modeling with polygenic indices approaches converge, albeit with the variance component estimates typically an order of magnitude greater than the trait-based estimates. We observe no indirect genetic effects of siblings on educational performance at any age, and only slightly negative indirect genetic effects of siblings on ADHD symptoms at age 3. We argue that the latter effect might reflect parental contrasting ratings. Conclusions The results suggest that within-family models of educational performance are unlikely to be drastically biased by an assumption of absent sibling indirect genetic effects. Combining trait-based analyses with variance component analyses can benefit understanding of indirect genetic effects, especially when the effects are not specific to a particular mechanism.

• Valstad, Mathias; Eftedal, Nikolai Haahjem; Yang, Tianfang; Kvarstein, Elfrida Hartveit; Reichborn-Kjennerud, Ted & Ystrom, Eivind [Show all 7 contributors for this article] (2026). The epidemiology of personality disorders in Norway: a nationwide patient registry study. Social Psychiatry and Psychiatric Epidemiology. ISSN 0933-7954. doi: 10.1007/s00127-026-03083-7. Full text in Research Archive
• Borren, Ingrid; Fruyt, Filip De; Bølstad, Evalill; Torvik, Fartein Ask; Røysamb, Espen & Gustavson, Kristin (2026). Development of Negative Emotionality in Mothers Across 18 Years: Does Relationship Breakup Matter? Journal of Personality. ISSN 0022-3506. p. 1–14. doi: 10.1111/jopy.70064. Full text in Research Archive Show summary

  Introduction Negative emotionality (NE) tends to decrease with age. However, we lack information about how divorce and other social role experiences predict long‐term development of NE in women after the transition to parenthood. Methods The current study used data from an 18‐year longitudinal study with eight data collection waves, including 823 mothers living with their child's father at baseline. Mixed models and Random Intercept Cross‐Lagged Panel Models were run. Results NE decreased over the 18‐year study period. The decline was steeper among mothers who were no longer in the relationship with the child's father at the end of the study period compared to mothers who stayed in that relationship. Mothers who broke up from a relationship with relatively high problem levels showed the steepest decline. Having four or more children living in the household was associated with less decrease in NE, probably due to initial low NE levels. Not living with a partner predicted temporarily elevated NE levels among mothers. Conclusion Decrease in NE among mothers is not entirely dependent on particular social role experiences or transitions. However, some experiences moderate the magnitude of this decrease, suggesting interrelatedness between decline in NE and social roles among mothers.

• Johannessen, Pia Myklebust; Madsen, Christian; Hart, Rannveig Kaldager; Lund, Ingunn Olea; Pettersen, Johanne Hagen & Gustavson, Kristin [Show all 10 contributors for this article] (2026). Protective factors for maternal mental health and life satisfaction during the COVID-19 pandemic: a longitudinal analysis. BMJ Open. 16(1), p. 1–11. doi: 10.1136/bmjopen-2025-110204. Full text in Research Archive Show summary

  Objective Mothers’ mental health and life satisfaction may have been negatively affected due to challenges during the COVID-19 pandemic. Given the risk of future crises, knowledge of possible mitigating factors in this population is essential. This study aims to examine whether the pandemic affected the level of protective factors such as social support, physical activity and employment situation, and how these factors are associated with mental distress and life satisfaction. Design Longitudinal cohort study. Outcome measures Primary outcomes were mental distress (measured by the eight-item version of the Hopkins Symptom Checklist) and life satisfaction (measured by the Satisfaction With Life Scale). As the first step, we investigated changes in the levels of social support (defined by the number and frequency of social contact), physical activity (average hours of physical activity during a week), employment situation (actively working vs sick leave or unemployed), alcohol consumption (measured by the Alcohol Use Disorders Identification Test-Consumption) and relationship satisfaction (measured by the five-item version of the Relationship Satisfaction Scale). Methods We analysed data from two waves of the Norwegian Mother, Father and Child Cohort Study (n=~18 000 mothers); one pre-pandemic wave and one wave where half of the sample responded after the onset of the pandemic, with pandemic exposure being defined by questionnaire response timing rather than cohort recruitment. To assess changes in protective factors over time and pandemic exposure, we used difference-in-differences analyses and regression discontinuity design. Associations between protective factors with mental distress and life satisfaction, and possible moderation by pandemic exposure, were investigated using multiple regression models with interaction terms adjusted for potential confounders. Results Apart from physical activity, which declined less across time in the pandemic group (B=0.09, 99% CI 0.05 to 0.12), protective factors did not change during the pandemic. Social support, employment situation and relationship satisfaction were associated with mental distress and life satisfaction, whereas physical activity showed a unique relationship with mental distress. Most associations were similar across pandemic exposure groups, except employment situation which appeared to have a stronger protective effect in the pandemic group (β=−0.12, 99% CI −0.24 to −0.00). Conclusions Changes over time in self-reported levels of protective factors were generally consistent among mothers independent of the pandemic. These factors appear to play an equally important role for mental distress and life satisfaction both under ordinary circumstances and during public health crises. Our findings enhance the understanding of how potential protective factors among mothers are associated with mental distress and life satisfaction in the context of a global stressor. Future studies should investigate additional mitigating factors that may be particularly relevant during global crises and explore the causal relationship between protective factors, mental health and life satisfaction.

• Eilertsen, Espen Moen; Eftedal, Nikolai Haahjem; Cheesman, Rosa Catherine Gillespie; Ayorech, Ziada; Ebeltoft, Joakim Coleman & Sunde, Hans Fredrik [Show all 9 contributors for this article] (2026). Multivariate maternal effects across the internalizing–externalizing spectrum in childhood: results from the Norwegian mother, father, and child cohort study. Journal of Child Psychology and Psychiatry. ISSN 0021-9630. p. 1–13. doi: 10.1111/jcpp.70111. Full text in Research Archive Show summary

  Background From a functionalist perspective, parenting behaviors have adaptive functions and are partly expressions of genetic variation. Maternal genes that have effects on children are often referred to as indirect maternal genetic effects. Indirect genetic effects provide a means for measuring the role of parenting without the need for specifying the relevant parental behaviors. We studied indirect maternal genetic effects to address both the importance and commonality of parenting across the internalizing–externalizing spectrum of behavior problems in childhood. We further addressed how indirect genetic effects impact our understanding of direct genetic effects if not accounted for. Methods Utilizing data from the Norwegian Mother, Father, and Child Cohort Study (MoBa), our analyses involved 42,423 children and their mothers. Both pedigree and genotype data were used to infer genetic relationships. We applied multivariate latent variable models to distinguish indirect maternal genetic effects and direct offspring genetic effects on seven measures of internalizing–externalizing behaviors. Results Our findings indicate significant maternal genetic influences, explaining 7%–18% of the variance across internalizing–externalizing behaviors. A general maternal effect common across behaviors could adequately account for most of the variability. The analyses further indicate that direct child genetic effects appear smaller and more complex when indirect maternal genetic effects are modeled simultaneously. Conclusions By summarizing the effects of parenting with indirect maternal genetic effects, we show a substantial contribution of parents with respect to internalizing–externalizing behaviors in childhood. Although parenting is multifaceted, the effects of parenting are general and can succinctly be described as a single common dimension. Further, our study demonstrates that direct genetic effects appear smaller and more complex when maternal genetic effects are accounted for, highlighting the confounding potential of parental effects in understanding the role of genetic differences in child psychopathology.

• Severinsen, Yvonne; Ystrom, Eivind; Eftedal, Nikolai Haahjem; Nygaard, Egil; Bekkhus, Mona & Viana, Karine Porpino [Show all 9 contributors for this article] (2026). Determinants of Parental Emotion Socialization Behaviors: Insights From a Large‐Scale Population‐Based Family Study. Scandinavian Journal of Psychology. ISSN 0036-5564. 67(4), p. 953–971. doi: 10.1111/sjop.70082. Full text in Research Archive Show summary

  ABSTRACT Parental emotion socialization behaviors (ESBs) are essential for child development and are typically understood as influenced by factors related to three domains: the parent, the child, and the family context. However, it remains unclear how parents' childhood experiences with ESBs should be represented within these conceptual frameworks. Addressing the complexity of ESBs, the present study examined predictors across three theoretically derived domains and additionally included parents' recollected ESBs as a parent‐level factor. Questionnaire data were collected from a large population‐based cohort of Norwegian mothers and fathers ( n  = 4207; 2460 mothers) with children aged 3 to 13 years ( M  = 7.4 years). Supportive and non‐supportive ESBs were examined separately through hierarchical regression models incorporating parent, context, and child factors. The three domains collectively accounted for 28% of the variance in supportive ESBs and 29% in non‐supportive ESBs. The results clearly emphasized parental factors, with parent gender and recollected ESBs being the most influential predictors. Other parent factors, such as perceived parenting stress, alcohol use, and the personality traits agreeableness and openness, also showed unique effects across both types of ESBs. Among contextual factors, education, income, and country of birth predicted non‐supportive ESBs but not supportive ESBs. Child age and birth order were linked with supportive ESBs, whereas only child age predicted non‐supportive ESBs. Findings highlight the importance of parent characteristics, particularly gender and recollected emotion socialization from the family of origin, in predicting current parental ESBs beyond contextual and child‐related factors.

• Svendsrud, Hedvig; Bekkhus, Mona; Lund, Olaf; Shai, Dana; Spencer, Rose & Smith, Lars [Show all 10 contributors for this article] (2026). Does expectant fathers' attachment style or depressive mood relate to their embodied mentalizing capacity of their 12-month-old infant? Acta Psychologica. ISSN 0001-6918. 263, p. 1–12. doi: 10.1016/j.actpsy.2026.106224. Full text in Research Archive Show summary

  Parental embodied mentalizing is about how parents show with their body that they hold in mind their infants' mind. The main study's aim was to explore what influences fathers' embodied mentalizing. A random sample of 200 fathers and their 12-month-old infants were drawn from a large longitudinal, population-based dataset, the "Little in Norway (LiN)" study. Fathers' partner related attachment style was assessed at enrollment, symptoms of depression were measured four times during pregnancy and at 12 months postpartum, as was also parenting stress. Videotaped father-infant interactions were coded with the Parental Embodied Mentalizing Assessment (PEMA). Results showed that fathers of girls were demonstrating a higher capacity for embodied mentalizing compared to fathers of boys. There were no direct effects of prenatal depressive symptoms or attachment style on fathers embodied mentalizing, suggesting that lower levels of attachment insecurity and depressive symptoms do not necessarily compromise fathers' capacity for embodied mentalizing. However, depressive symptoms during pregnancy increased the likelihood of postpartum depressive symptoms and parenting stress. In combination, these increased risks were related to poorer embodied mentalizing in fathers. This suggests that being depressed both during pregnancy and when the infant is 12 months, as well as experiencing stress in the parenting role, may be risk factors for compromised embodied mentalizing.

• Nerland, Stener; Barth, Claudia; Jørgensen, Kjetil Nordbø; Bakke, Laura Anne Wortinger; Castro-Fornieles, Josefina & Díaz-Caneja, Covadonga M. [Show all 44 contributors for this article] (2026). Cerebral cortical alterations in adolescent early-onset psychosis: a surface-based morphometry mega-analysis. Molecular Psychiatry. ISSN 1359-4184. doi: 10.1038/s41380-026-03641-0. Full text in Research Archive Show summary

  Abstract Cortical brain morphology in early-onset psychosis (EOP; age of onset < 19 years) is poorly understood, partly due to recruitment constraints linked to its low incidence. We pooled T1-weighted magnetic resonance imaging (MRI) data from 387 adolescents with EOP (mean age=16.1±1.5; 49.6% female) and 338 healthy controls (CTR; mean age=15.8±1.9, 54.4% female) from nine research sites worldwide. Using harmonized processing protocols with FreeSurfer, we extracted cortical brain metrics from 34 bilateral regions. Univariate regression analysis revealed widespread lower bilateral cortical thickness (left/right hemisphere: d =-0.36/-0.31), surface area (left/right: d =-0.42/-0.41), cortical volume (left/right: d =-0.58/-0.56), and Local Gyrification Index (LGI; left/right: d =-0.39/-0.52) in EOP relative to CTR. Subgroup analyses showed broader and more pronounced case-control differences in early-onset schizophrenia for area, volume, and LGI. We found no associations with antipsychotic medication use, illness duration, age of onset, or positive symptoms. Negative symptoms were related to smaller left lingual volumes (partial r =-0.21; p FDR =0.014) and antidepressant users had smaller area ( d =-0.43; p FDR =0.034) and volume ( d =-0.50; p FDR =0.003) of the right rostral anterior cingulate compared to non-users. Cortical alterations in EOP showed a similar pattern to those observed in prior studies on adults with schizophrenia (SCZ; r =0.62) and bipolar disorders (BD; r =0.61). However, surface area alterations were overall 1.5 times greater for EOP than adult SCZ and 4.6 times greater than adult BD. In the largest study of its kind, we observed an extensive pattern of cortical alterations in adolescents with psychotic disorders, highlighting the potential impact of aberrant neurodevelopment on cortical morphology in this clinical group.

• Ebeltoft, Joakim Coleman; Ystrøm, Eivind; Ayorech, Ziada & Eilertsen, Espen Moen (2026). Parental wealth and mental disorders in Norway (2006–2023): a nationwide registry-based study of 1.4 million young people. The Lancet Regional Health - Europe. 62. doi: 10.1016/j.lanepe.2025.101567. Full text in Research Archive Show summary

  Background Young people from families with low socioeconomic position have higher rates of mental disorders. However, wealth is underexamined despite large wealth inequity worldwide. Here, we aim to investigate the relationship between early life parental wealth and mental disorders in young Norwegians. Methods We conducted a population study of associations between early-life parental wealth and 17 diagnostic categories of mental disorders in 1.4 M children (7–12), adolescents (13–18), and young adults (19–24) observed 2006–2023. Ranked parental socioeconomic indicators at age 0–6 (wealth, income, occupation, and education) and mental disorder diagnoses (ICD-10 and ICPC-2) were obtained from Norwegian Tax, Employment, Education, and Control and Payment of Health Reimbursements registries. Estimates were derived from mean prevalences, generalised estimating equations, and sibling comparison designs. Findings Parental wealth represents a gradient in young people’s mental disorders across age, sex, diagnostic categories, and cohorts. The lowest wealth quintile demonstrated 87% [95% CI = 78–96%] higher 1-year prevalence than the highest quintile. In multivariable analyses, parental wealth was the strongest predictor of mental disorders relative risk in adolescents (1.83 [1.76–1.9]) and young adults (1.92 [1.8–2.04]), while wealth (1.53 [1.46–1.6]) and education (1.52 [1.45–1.6]) were the strongest predictors in children. Parental wealth has a significant within-family association with mental disorders (relative risks: children 1.57 [1.44–1.71], adolescents 1.34 [1.26–1.42], young adults 1.42 [1.31–1.54]). Interpretation Our study serves as a point of reference for understanding the relationship between parental wealth and mental health. Our findings establish early life parental wealth as a fundamental social gradient in young people’s mental disorders.

• Dardani, Christina; Robinson, Jamie W; Havdahl, Alexandra; Darrous, Liza; Jones, Hannah J & Zammit, Stan [Show all 20 contributors for this article] (2026). Revisiting the Links Between Asthma and the Psychosis Spectrum: shared molecular mechanisms. Biological Psychiatry. ISSN 0006-3223. doi: https:/www.sciencedirect.com/science/article/pii/S0006322326014629. Full text in Research Archive
• Chegeni, Razieh; Nes, Ragnhild Bang; Cheesman, Rosa Catherine Gillespie; Ayorech, Ziada Ng'ombo Laurel; Ystrøm, Eivind & Røysamb, Espen (2026). Parental direct and indirect genetic effects on offsprings’ internalizing problems across development. Nature Mental Health. doi: https:/www.researchsquare.com/article/rs-6862539/v1. Full text in Research Archive Show summary

  Internalizing problems are common in youth and linked to adverse long-term outcomes. While both children’s own genetic variants (direct genetic effects) and the genetics of their parents (indirect genetic effects) contribute, the direct and indirect genetic traits involved remain unclear. Here, w...

• Potočár, Libor; Cachón-Alonso, L; Kozák, Michal; Rodríguez-Cano, Rubén; Formánek, T & Soest, Tilmann von (2025). The interplay between loneliness and health factors from adolescence to midlife: a cohort study. European Journal of Public Health. ISSN 1101-1262. 35(Supplement 4). doi: 10.1093/eurpub/ckaf161.1152. Full text in Research Archive Show summary

  There is growing evidence of adverse health outcomes among lonely individuals, with health behaviors representing one potential underlying mechanism. However, existing research overlooked the potential gender-specific dynamic interplay of health behaviors and loneliness across the first decades of life. In this Norwegian 28-year prospective cohort study (n = 3,072) from adolescence to midlife, we investigated reciprocal relationships between loneliness and health factors, including alcohol use, body mass index (BMI), smoking status, and physical exercise. Using a structural nested mean modeling approach with G-estimation, we accounted for a comprehensive set of baseline and time-varying confounders. We demonstrated that increased loneliness among adolescent males diminished subsequent physical exercise and that elevated loneliness during adolescence and/or young adulthood was linked to a subsequent increase in BMI among both males and females. The remaining loneliness-health behavior relationships were consistent with a null effect. Considering the effect of health factors on loneliness, physical exercise in adolescent males decreased subsequent loneliness, whereas obesity among females during young adulthood was linked to an increase in loneliness. In summary, except for a loneliness-physical exercise interplay in adolescent males and a loneliness-BMI interplay in females, our results provide limited support for gender-specific reciprocal relationships between loneliness and health factors across the first decades of life.

• Nygaard, Egil (2025). OSF project preregistration: HeaLS - Effects of the implementation of the interdisciplinary topic "Health and life skills" in schools. Open Science Framework (OSF). Full text in Research Archive
• Braithwaite, Elizabeth C.; Haftorn, Kristine Løkås; Oftedal, Aurora; Ayorech, Ziada; Kaasen, Anne & Murgatroyd, Christopher [Show all 9 contributors for this article] (2025). Associations between lifetime history of depression, prenatal OXTR DNA methylation and breastfeeding outcomes. Clinical Epigenetics. 18(1), p. 1–12. doi: 10.1186/s13148-025-02030-8. Full text in Research Archive Show summary

  Abstract Background Women with depression are less likely to breastfeed and experience more breastfeeding challenges. Potential biological mechanisms that link maternal depression with poor breastfeeding outcomes have not been investigated. This study examined associations between lifetime history of depression (LHD), prenatal oxytocin receptor gene ( OXTR ) DNA methylation, and breastfeeding outcomes. Results Longitudinal observational data from the Norwegian Mother, Father and Child Cohort Study (MoBa) were analysed (N = 3607). LHD was self-reported during pregnancy (week 15). Blood samples were collected at 16–18 weeks of pregnancy, and DNA methylation was measured using the Illumina Methylation EPIC BeadChip 850 K array. This array includes 22 CpG sites on the OXTR gene, which were used in analyses. Mothers self-reported breastfeeding initiation (breastmilk given to child in first month), breastfeeding maintenance (breastmilk given to child for 6 months or more) and breastfeeding problems. Maternal LHD was not associated with OXTR DNA methylation. There was some evidence that prenatal OXTR DNA methylation was associated with breastfeeding outcomes. There was an association between CpG cg26455676 and breastfeeding maintenance to 6 months (odds ratio = 1.59, 95% confidence intervals = 1.11–2.27, raw p  = 0.01, adjusted p  = 0.04). Higher levels of DNA methylation at CpG cg26455676 was associated with a greater likelihood of maintaining breastfeeding to 6 months. Conclusions This highly novel study highlights the intriguing possibility that maternal prenatal DNA methylation at genes important for breastfeeding may be associated with breastfeeding experiences. Further understanding of vastly differing breastfeeding experiences would assist with the targeting efforts to support breastfeeding women, particularly those who are vulnerable, such as mothers who have depression.

• Eilertsen, Maja; Hansen, Thomas; Torre, Maria Julia Bidonde; Reneflot, Anne; Nilsen, Thomas Sevenius & Czajkowski, Nikolai Olavi [Show all 7 contributors for this article] (2025). Effects of Positive Psychology Interventions on Inflammatory Biomarkers and Cortisol: A Systematic Review and Meta-Analysis. International Journal of Applied Positive Psychology. ISSN 2364-5040. 10(4), p. 1–33. doi: 10.1007/s41042-025-00258-6. Full text in Research Archive Show summary

  Abstract There is growing interest in how well-being-enhancing activities influence stress and health. Positive psychology interventions (PPIs) foster such activities, but evidence regarding their physiological effects remains fragmented. This review aimed to examine the effects of PPIs on two physiological indicators of stress via a systematic literature review and meta-analysis. We included randomized controlled trials (RCTs) assessing the effects of PPIs on inflammatory biomarkers and/or cortisol in adult clinical and non-clinical populations. Searches were conducted in MEDLINE, Embase, PsycINFO, Epistemonikos, and clinical trial registries (from January 2000 to June 2023). Two reviewers independently screened studies, extracted data, and assessed risk of bias. Random-effects meta-analyses using robust variance estimation accounted for statistical dependencies. Effects were reported as Cohen’s d with 95% confidence intervals (CIs) and heterogeneity as prediction intervals (PIs). Twenty-five RCTs ( N  = 1,641) were included. Common PPIs included music, nature exposure, gratitude, optimism, kindness, and meaning-focused activities. The overall effect was d  = 0.39 (95% CI: 0.16, 0.62). The effect estimates were significant for inflammatory biomarkers ( d  = 0.46, 95% CI: 0.02, 0.89), but not for cortisol ( d  = 0.30, 95% CI: − 0.10, 0.71). A significant effect was observed in clinical groups ( d  = 0.61, 95% CI: 0.17, 1.04); the effect in non-clinical groups was non-significant ( d  = 0.23, 95% CI: − 0.01, 0.79). High heterogeneity and risk of bias warrant cautious interpretation. These findings suggest that PPIs may reduce inflammatory biomarkers. The clinical relevance of these effects remains uncertain and warrants further investigation, particularly in relation to long-term outcomes. Registration : The study protocol was registered with PROSPERO (CRD42023438736).

• Berger, Eirik Jerven & Bakken, Silje Anderdal (2025). A digital–physical continuum of illegal drug markets: Networks, trust, and culture. Acta Sociologica. ISSN 0001-6993. doi: 10.1177/00016993251356344. Full text in Research Archive Show summary

  Social relationships are a fundamental part of illegal drug markets. However, drug market categorizations, such as online/offline, open/closed, and public/private, overshadow the everyday purchase and sale of illegal drugs. Highlighting the significance of social relationships reveals the complexity and fluidity of real-life drug market activities. By using the economic sociological theory, we bridge the gap between online and offline drug market research by merging two datasets of qualitative interviews, focusing on Norway's physical and online drug markets. Combined the data consist of in-depth interviews with 100 market participants. We find that market relationships vary on a continuum between being fully digital to fully physical. Moreover, participants’ positions on this continuum are not fixed on one market category. Individuals’ participation is determined by several interconnected factors, including social networks, risk and trust, and drug and street culture. Hence, despite technological advancements and new possibilities, the purchase and sale of illegal drugs take place on a digital–physical continuum determined by social and relational factors.

• Hofgaard, Live Skow; Nes, Ragnhild Bang; Vassend, Olav Mandt; Ayorech, Ziada; Czajkowski, Nikolai Olavi & Røysamb, Espen (2025). Mental illbeing and wellbeing are influenced by recent adverse life events. Evidence from a longitudinal twin study. Current Psychology. ISSN 1046-1310. 44, p. 8723–8735. doi: 10.1007/s12144-025-07758-3. Full text in Research Archive Show summary

  Adverse life events have been associated with increased mental illbeing and decreased wellbeing. These associations may partly reflect reverse causality and confounding genetics. Few studies have accounted for such effects, and few have compared the effect of adversities within and across different mental health outcomes. Our sample includes 1987 monozygotic and dizygotic twins born 1945-60, in the Norwegian Twin Registry, who responded to two questionnaires six years apart. We used biometric modelling to estimate genetic overlap and linear mixed models to control for previous levels of illbeing and wellbeing as well as genetic confounding in the associations between adverse life events and these outcomes. Our results indicate causal effects of cumulative adversity on increased illbeing and decreased wellbeing. Of the six adversities examined separately, financial strain and conflicts in romantic relationships showed the most profound effect on both outcomes. Conflicts with family/friends/neighbours and problems at work seem to primarily increase illbeing, while serious illness or injury mainly decrease wellbeing. This study supports previous findings that cumulative adversity represents a risk for increased illbeing and decreased wellbeing. Hence, exploring the number of recent adverse events could give valuable insight into individuals’ stressor load, and the reduction and prevention of such events should be important targets for preventive programs and policy. Importantly, our findings further suggest that the events that increase illbeing are not always overlapping with those that decrease wellbeing. This should be taken into consideration when assessing the needs of individuals after difficult experiences.

• Tamnes, Christian K.; Bekkhus, Mona; Eilertsen, Maja; Nes, Ragnhild Bang; Prydz, Monica Beer & Ystrom, Eivind [Show all 63 contributors for this article] (2025). The nature of the relation between mental well-being and ill-being. Nature Human Behaviour. 9(12), p. 2431–2440. doi: 10.1038/s41562-025-02319-x. Full text in Research Archive
• Liu, Siwei; Agartz, Ingrid; Allen, Paul; Amminger, G. Paul; Andreassen, Ole & Bachman, Peter [Show all 113 contributors for this article] (2025). Structural covariance network topology in individuals at clinical high risk for psychosis: the ENIGMA-CHR Study. Molecular Psychiatry. ISSN 1359-4184. doi: 10.1038/s41380-025-03304-6. Full text in Research Archive Show summary

  Brain network architecture is anticipated to influence future grey matter loss in individuals at Clinical High Risk (CHR) for psychosis. However, existing studies on grey matter structural network properties in CHR are scarce and constrained by small sample sizes. Here, we examined network topology differences comparing a) CHR versus healthy controls (HC); b) CHR who transitioned to psychosis (CHR-T) versus those who did not (CHR-NT); and c) different subsyndromes. We included structural scans from 1842 CHR individuals and 1417 HC individuals from 31 sites within the Enhancing NeuroImaging Genetics through Meta-Analysis (ENIGMA) consortium. At the global level, CHR individuals exhibited lower structural covariance (q < 0.001; Cohen’s d = 0.164) and less optimal structural network configuration than HC (lower global efficiency and clustering coefficient, d = 0.100,0.087, qs <= 0.027). Though no global difference between CHR-T and CHR-NT, network distinctiveness of the frontal and temporal surface area networks was higher in CHR-T than CHR-NT (d = 0.223,0.237) and HC (d = 0.208,0.219) (qs < 0.001). Network distinctiveness of the frontal cortical thickness network was lower in CHR-T (d = 0.218, q < 0.001) than CHR-NT and HC (d = 0.165, q < 0.001). Importantly, higher network distinctiveness was associated with worse positive symptoms in CHR-NT (frontal surface area, q = 0.008, R2 = 0.013) and at trend with worse negative symptoms in CHR-T (frontal thickness, q = 0.063, R2 = 0.049). Further, the brief intermittent psychotic syndrome subgroup showed more severe network alterations. Together, brain structural networks inform symptoms and the risk of transition to psychosis in CHR individuals.

• Krogsrud, Stine Kleppe; Nordeng, Hedvig Marie Egeland; Roe, James Michael; Torkildsen, Janne von Koss; Wood, Mollie Elizabeth & Ystrøm, Eivind (2025). Associations between prenatal paracetamol exposure and brain development from ages 4–16: A longitudinal MRI study. Developmental Cognitive Neuroscience. ISSN 1878-9293. 78. doi: 10.1016/j.dcn.2025.101667. Full text in Research Archive Show summary

  Research has raised concerns regarding the potential impact of prenatal paracetamol exposure on fetal neurodevelopment. This is the first longitudinal study to investigate whether such exposure is related to structural brain development and cognitive abilities during childhood and adolescence. The sample includes 447 children aged 4.1–16.2 years with 905 MRI scans. The study is based on The Norwegian Mother, Father and Child Study (MoBa), and uses data from the Medical Birth Registry of Norway. The exposure variable is mothers’ self-reported use of paracetamol from prenatal and postnatal questionnaires. Among 447 children (229 girls; mean age 8.38 years), 193 (43.2 %) were prenatally exposed. Days of exposure range from 1 to 128 (mean 8.2). Vertex-wise linear mixed effect models showed that exposed children (n = 193; 393 scans) had slightly smaller cortical surface area and volume in some regions compared to non-exposed children. These results were seemingly driven by long-term exposed children (≥14 days in utero; n = 35; 72 scans, and exposed in all three trimesters, n = 21; 44 scans). However, group differences in brain structure were small with largely overlapping distributions, and the observational design and risk of unmeasured confounding preclude causal inference. Thus, the clinical significance remains uncertain. For cognitive abilities, results were reassuring showing no significant effect of prenatal paracetamol exposure on working memory capacity or IQ scores.

• Zugic, Milica; Trinh, Nhung; Rostami, Sina; Nordeng, Hedvig Marie Egeland; Ystrøm, Eivind & Bulik, Cynthia M [Show all 10 contributors for this article] (2025). Antenatal depressive and anxiety symptoms in women with eating disorders who continue or discontinue antidepressant treatment in pregnancy. Journal of Affective Disorders Reports. 22, p. 1–10. doi: 10.1016/j.jadr.2025.100985. Full text in Research Archive Show summary

  Background Limited evidence on antidepressant effectiveness in pregnant women with eating disorders (ED) challenges pharmacotherapy management. We examined antenatal depressive and anxiety symptoms with continued antidepressant use in women with ED. Methods We used data from the Norwegian Mother, Father and Child Cohort Study (MoBa) linked to the Medical Birth Registry of Norway and MoBa Genetics. MoBa questionnaires at weeks 17 (early) and 30 (mid-late pregnancy) measured antidepressant exposure and symptoms of depression and anxiety using the 5-item Hopkins Symptom Checklist. We fitted generalised linear models and adjusted for confounding. In a subsample, we stratified analyses by polygenic-score tertiles for antidepressant response. Results We identified 5920 pregnancies in women with ED, mainly binge-eating disorder (BED) (84.0 %) and bulimia nervosa (BN) (12.4 %). Of these, 48 (0.8 %) continued antidepressants into early pregnancy, 93 (1.6 %) discontinued during, and 85 (1.4 %) discontinued before pregnancy. At early pregnancy only, continued antidepressant was associated with lower severity of depressive and anxiety symptoms relative to discontinuation. Among women with BED, this was specific to lower anxiety symptoms (β:-0.43, 95 %CI:-0.84, -0.02). This association was not observed in women with BN. In women with higher antidepressant-response polygenic-score continued antidepressant was associated with lower symptom severity relative to discontinued (range of β:-0.86 to -1.35). Conclusions Continuing antidepressants in early but not mid-late pregnancy is associated with lower severity of depressive and anxiety symptoms in women with BED. The association observed in women with higher antidepressant-response polygenic-score calls for larger studies on personalized treatment in perinatal ED.

• Vira, Emily Gabriela; Nes, Ragnhild Bang; Kaasbøll, Jannike; Kjøbli, John; Røysamb, Espen & Helland, Siri Saugestad (2025). Reciprocal associations between general psychopathology and emotion regulation from adolescence to adulthood. International Journal of Behavioral Development. ISSN 0165-0254. p. 1–14. doi: 10.1177/01650254251401322. Full text in Research Archive Show summary

  Emotion regulation (ER) is central to most mental health difficulties. However, we know less about the impact of mental health on ER, particularly during vulnerable developmental periods. This study examines longitudinal associations between ER strategies and general psychopathology from adolescence to adulthood, distinguishing between- and within-person effects across 1 and 13 years. Norwegian adolescents (N = 2,464, 51% female, mean age = 13.7) were followed into adulthood (N = 1,266, 56.7% female, mean age = 27.2). Five ER strategies, including rumination, reactive impulsivity, non-acceptance, problem-solving, and seeking social support, were assessed. Using Random Intercept Cross-Lagged Panel Models, within-person analyses revealed that more than usual psychopathology predicted more than usual rumination, reactive impulsivity, and non-acceptance 1 year later. Only more than usual reactivity reciprocally predicted more than usual psychopathology 1 year later. More than usual psychopathology during adolescence predicted less social support seeking than usual during adulthood, and more social support seeking than usual during adolescence predicted fewer symptoms of psychopathology than usual during adulthood. There were no significant associations between problem-solving and psychopathology. We found reciprocal and unidirectional associations between general psychopathology and ER strategies, highlighting ER as both a risk and protective factor, but also illuminating the role general psychopathology has on ER.

• Chen, Sau-Chin; Buchanan, Erin M.; Kekecs, Zoltan; Miller, Jeremy K.; Szabelska, Anna & Aczel, Balazs [Show all 114 contributors for this article] (2025). Investigating object orientation effects across 18 languages. Current Psychology. ISSN 1046-1310. 44(24), p. 19174–19174. doi: 10.1007/s12144-025-08304-x. Full text in Research Archive Show summary

  Mental simulation theories of language comprehension propose that people automatically create mental representations of objects mentioned in sentences. Mental representation is often measured with the sentence-picture verification task, wherein participants first read a sentence that implies the object property (i.e., shape and orientation). Participants then respond to an image of an object by indicating whether it was an object from the sentence or not. Previous studies have shown matching advantages for shape, but findings concerning object orientation have not been robust across languages. This registered report investigated the match advantage of object orientation across 18 languages in nearly 4,000 participants. The preregistered analysis revealed no compelling evidence for a match advantage for orientation across languages. Additionally, the match advantage was not predicted by mental rotation scores. In light of these findings, we discuss the implications for current theory and methodology surrounding mental simulation.

• Aksnes, Eira R.; Birkeland, Marianne Skogbrott; Ebrahimi, Omid V.; Bekkhus, Mona; Ferschmann, Lia & Beck, Dani [Show all 12 contributors for this article] (2025). Developmental dynamics of symptoms of emotional problems in childhood and adolescence: A longitudinal network analysis. JCPP Advances. doi: 10.1002/jcv2.70079. Full text in Research Archive Show summary

  Abstract Background Epidemiological studies document increasing incident rates of mental disorders across childhood and adolescence, with mood and anxiety disorders particularly increasing among adolescent females. Research also indicates that these emotional problems have become more prevalent in recent decades. Yet, there is still a lack of understanding of the interrelated development of distinct emotional symptoms from childhood to adolescence. Methods Here, we investigate and compare symptom dynamics in males and females. To accomplish this, we leveraged longitudinal data from the Avon Longitudinal Study of Parents and Children study ( N  = 11,120, 50.1% males at baseline). We used five items ( worries , unhappy , nervous , fearful , somatic complaints ) derived from the parent‐reported Strength and Difficulties Questionnaire emotional problems scale, measured at up to seven timepoints (mean age = 9.52, range = 4.0–18.3 years old). We estimated a panel Graphical Vector Autoregressive network model (GVAR) and statistically compared the networks of males and females. Results The temporal network revealed largely reciprocal associations among symptoms, with the strongest edges between fearful–nervous and unhappy–worries ( β  = 0.04–0.06). The contemporaneous and between‐person networks showed similar structures, although the between‐person network exhibited fewer but stronger associations, reflecting more stable individual differences. Somatic complaints were weakly connected in the temporal network but more strongly associated in contemporaneous and between‐person networks. Network invariance testing indicated no significant sex differences in average network structure. Conclusion The study delineates the developmental dynamics of emotional symptoms across childhood and adolescence, highlighting bidirectional influences between core symptoms of depression and anxiety, but did not find support for sex differences in their developmental interrelatedness.

• Norbom, Linn B.; Eilertsen, Espen Moen; Dahl, Andreas; Karl, Valerie; Westlye, Lars Tjelta & Tamnes, Christian K. (2025). Socioeconomic context influences the heritability of child cortical structure. Communications Biology. 8. doi: 10.1038/s42003-025-09022-7. Full text in Research Archive Show summary

  Children differ in brain cortical morphometry and microstructure, which together form the structural foundation for cognition. Cortical structure is highly heritable, but whether heritability varies across socioeconomic status (SES) is unknown. In this preregistered study, we estimated single-nucleotide polymorphism (SNP)-based heritability of cortical thickness, surface area, sulcal depth, and grey-/white-matter contrast (GWC) among 9,080 US 10-year-olds. We then tested whether genetic and environmental contributions were moderated by parental SES, defined as a composite of income, education, and neighbourhood deprivation. Cortical thickness and surface area showed high heritability, while sulcal depth and GWC exhibited moderate heritability. However, among children from lower-SES backgrounds, cortical differences were less genetically related and more uniquely environmentally related, at times exceeding genetic contributions. These findings suggest that in contexts of socioeconomic disadvantage, children’s brain structure reflect lived experience more strongly than previously recognized.

• M., Buchanan, Erin; A., Acar, Oguz; Balazs, Aczel,; Matúš, Adamkovič,; Giulia, Agnoletti, & M., Akil, Atakan [Show all 324 contributors for this article] (2025). Measuring the semantic priming effect across many languages. Nature Human Behaviour. doi: 10.1038/s41562-025-02254-x. Full text in Research Archive Show summary

  Semantic priming has been studied for nearly 50 years across various experimental manipulations and theoretical frameworks. Although previous studies provide insight into the cognitive underpinnings of semantic representations, they have suffered from small sample sizes and a lack of linguistic and cultural diversity. In this Registered Report, we measured the size and the variability of the semantic priming effect across 19 languages (n = 25,163 participants analysed) by creating the largest available database of semantic priming values using an adaptive sampling procedure. We found evidence for semantic priming in terms of differences in response latencies between related word-pair conditions and unrelated word-pair conditions. Model comparisons showed that the inclusion of a random intercept for language improved model fit, providing support for variability in semantic priming across languages. This study highlights the robustness and variability of semantic priming across languages and provides a rich, linguistically diverse dataset for further analysis. The Stage 1 protocol for this Registered Report was accepted in principle on 15 July 2022. The protocol, as accepted by the journal, can be found at https://osf.io/u5bp6 (registration) or https://osf.io/q4fjy (preprint version 6, 31 May 2022). In this Stage 2 Registered Report, Buchanan et al. show evidence confirming the phenomenon of semantic priming across speakers of 19 diverse languages.

• Heyman, Tom; Pronizius, Ekaterina; Lewis, Savannah C.; Acar, Oguz A.; Adamkovič, Matúš & Ambrosini, Ettore [Show all 66 contributors for this article] (2025). Crowdsourcing multiverse analyses to explore the impact of different data-processing and analysis decisions: A tutorial. Psychological methods. ISSN 1082-989X. doi: 10.1037/met0000770. Full text in Research Archive Show summary

  When processing and analyzing empirical data, researchers regularly face choices that may appear arbitrary (e.g., how to define and handle outliers). If one chooses to exclusively focus on a particular option and conduct a single analysis, its outcome might be of limited utility. That is, one remains agnostic regarding the generalizability of the results, because plausible alternative paths remain unexplored. A multiverse analysis offers a solution to this issue by exploring the various choices pertaining to data-processing and/or model building, and examining their impact on the conclusion of a study. However, even though multiverse analyses are arguably less susceptible to biases compared to the typical single-pathway approach, it is still possible to selectively add or omit pathways. To address this issue, we outline a novel, more principled approach to conducting multiverse analyses through crowdsourcing. The approach is detailed in a step-by-step tutorial to facilitate its implementation. We also provide a worked-out illustration featuring the Semantic Priming Across Many Languages project, thereby demonstrating its feasibility and its ability to increase objectivity and transparency.

• Tveit, Olav Bertin; Røysamb, Espen & Gustavson, Kristin (2025). Consulting Children When Parents Divorce: Longitudinal Associations with Mental Health and Parent–Child Relationship Outcomes. Family Transitions. ISSN 2837-5300. 66(7), p. 455–478. doi: 10.1080/28375300.2025.2527996. Full text in Research Archive
• Nguyen, Huong Thu; Ystrøm, Eivind; Gjerde, Line Cecilie & Næss, Øyvind Erik (2025). Life course socioeconomic position and the risk of cardiovascular events and all-cause mortality in a Norwegian twin study. Scientific Reports. 15. doi: 10.1038/s41598-025-16975-6. Full text in Research Archive
• Oftedal, Aurora; Kaasen, Anne; Karlsen, Taran; Haugen, Guttorm Nils & Bekkhus, Mona (2025). Maternal Distress in Pregnancies After Previous Fetal Anomaly: A Longitudinal Cohort Study. BJOG: An International Journal of Obstetrics and Gynaecology. ISSN 1470-0328. doi: 10.1111/1471-0528.18343. Full text in Research Archive Show summary

  Objective To assess mental health throughout pregnancy among women with a history of diagnosis of fetal anomaly. Design Prospective observational study. Setting Tertiary referral centre for fetal medicine. Population Pregnant women with a history of fetal anomaly (study group; n  = 75) and women without such a history (comparison group; n  = 111). A subgroup of women in the study group ( n  = 28) participated in two different pregnancies, where the first had a diagnosis of fetal anomaly and the second did not. Methods Women completed the Edinburgh Postnatal Depression Scale (EPDS) and Impact of Events Scale (IES) at four timepoints between gestational age 18 weeks and 36 weeks. Main Outcomes Trajectories of EPDS and IES across time in the study group and comparison group, as well as differences in EPDS and IES in the healthy pregnancy and the pregnancy with a diagnosis of fetal anomaly in the subgroup. Results Having a history of previous diagnosis of fetal anomaly was associated with elevated levels of depression and traumatic stress throughout pregnancy, even in healthy pregnancies (e.g., EPDS mean difference = 2.65, 95% CI [1.91, 3.21]). The difference between groups was largest early in pregnancy and decreased with increasing gestational age. Furthermore, women in the subgroup experienced much higher levels of distress in the pregnancy with a diagnosis of fetal anomaly than in their healthy pregnancy (e.g., EPDS mean difference = 8.7, 95% CI [6.40, 11.15]). Conclusion The results highlight the importance of considering women's history of fetal anomaly and prenatal loss even in healthy pregnancies.

• Bjørndal, Ludvig Daae; Wootton, Robyn; Ebrahimi, Omid V.; Piazza, Giulia G.; Hegemann, Laura Elizabeth & Corfield, Elizabeth Claire [Show all 11 contributors for this article] (2025). Unravelling symptom-specific polygenic effects on maternal mental health during the perinatal period and postpartum. Journal of Affective Disorders. ISSN 0165-0327. 392. doi: 10.1016/j.jad.2025.120228. Full text in Research Archive
• Fluit, Sam; Overall, Nickola; Osborne, Danny; Hammond, Matthew & Sibley, Chris (2025). Intimate Partners’ Political Influence: Longitudinal Evidence for the Mutual Transmission of Party Support between Women and Men. Personality and Social Psychology Bulletin. ISSN 0146-1672. p. 1–14. doi: https:/journals.sagepub.com/doi/full/10.1177/01461672251360302. Full text in Research Archive Show summary

  Cross-sectional research demonstrates that intimate partners generally hold similar political preferences. It is unclear, however, whether intimate partners influence each other’s preferences over time. We address this oversight by investigating the transmission of political party support across 1,613 woman-man couples in long-term intimate relationships using 10 annual waves of longitudinal panel data. Actor-partner interdependence random intercepts cross-lagged panel models revealed that within-person increases in an intimate partner’s party support predicted within-person increases in the other couple member’s party support the following year. These partner effects emerged for six political parties in New Zealand and, with only one exception, did not differ in strength across women and men. Partner effects for self-rated political orientation were not significant. These results suggest that couples mutually reinforce each other’s political party support over time, advancing understanding of the interpersonal transmission of political preferences and identifying a dyadic process that may contribute to political polarization.

• Cheesman, Rosa Catherine Gillespie; Borgen, Nicolai T.; Sandsør, Astrid Marie Jorde & Hufe, Paul (2025). The Genetic Lottery Goes to School: Better Schools Compensate for the Effects of Students' Genetic Differences. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 122(43). doi: 10.1073/pnas.2511715122. Full text in Research Archive Show summary

  In this paper, we investigate whether better schools can compensate for the effects of children’s genetic differences. To this end, we combine data from the Norwegian Mother, Father, and Child Cohort Study (MoBa) with Norwegian register data to estimate the interaction between measures of children’s predisposition to education and school quality. We use MoBa’s genetic data to compute polygenic indices for educational attainment (PGIEA). Importantly, MoBa includes genetic data on mother-father-child trios, allowing us to identify causal genetic effects using within-family variation. We calculate school value-added measures from Norwegian register data, allowing us to causally estimate school quality effects. Leveraging the advantages of both data sources, we provide a causally identified study of gene–environment interactions in the school context. We find evidence for substitutability of PGIEA and school quality in reading but not numeracy: A 1 SD increase of school quality decreases the impact of a 1 SD increase of PGIEA on reading test scores by 6%. The substitutability arises through gains of students at the lower end of the PGIEA distribution. This suggests that investments in school quality may help reduce educational inequalities arising from genetic differences between students.

• Ferschmann, Lia; Tamnes, Christian Krog & Fridman, Linn Bonaventure (2025). Hjerneutvikling fra fosterlivet til voksen alder: Generelle mønstre og individuelle forskjeller. In Olavesen, Ellen Solstad; Holme, Hanne; Valla, Lisbeth & Hansen, Marit Bergum (Ed.), Helsestasjons- og skolehelsetjenesten - barn og unges psykiske helse og utvikling. 2. utgave.. Gyldendal Akademisk. ISSN 9788205615397. p. 19–38. Full text in Research Archive
• Skirbekk, Vegard Fykse; Tamnes, Christian K.; Juliusson, Pétur Benedikt; Jugessur, Astanand & Soest, Tilmann von (2025). Diverging trends in the age of social and biological transitions to adulthood. Advances in Life Course Research. ISSN 1569-4909. 65. doi: 10.1016/j.alcr.2025.100690. Full text in Research Archive
• Lindseth, Linn Renate Sjøveian; Beck, Dani; Westlye, Lars Tjelta; Tamnes, Christian K. & Fridman, Linn Bonaventure (2025). Linking pregnancy- and birth-related risk factors to a multivariate fusion of child cortical structure. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 122(25). doi: 10.1073/pnas.2422281122. Full text in Research Archive Show summary

  Pregnancy- and birth-related factors affect offspring brain development, emphasizing the importance of early life exposures. While most previous studies have focused on a few variables in isolation, here we investigated associations between a broad range of pregnancy- and birth-related variables and multivariate cortical brain MRI features. Our sample consisted of 8,396 children aged 8.9 to 11.1 y from the Adolescent Brain Cognitive Development Study. Through multiple correspondence analysis and factor analysis of mixed data, we distilled numerous pregnancy and birth variables into four overarching dimensions; maternal pregnancy complications, maternal substance use, low birth weight and prematurity, and newborn birth complications. Vertex-wise measures of cortical thickness (CT), surface area (SA), and curvature were fused using linked independent component analysis. Linear mixed-effects models showed that maternal pregnancy complications and low birth weight and prematurity were associated with smaller global SA. Additionally, low birth weight and prematurity was associated with complex regional cortical patterns reflecting bidirectional variations in both SA and CT. Newborn birth complications showed multivariate patterns reflecting smaller occipital- and larger temporal area, bidirectional frontal area variations, and reduced CT across the cortex. Maternal substance use showed no associations with child cortical structure. By employing a multifactorial and multivariate morphometric fusion approach, we connected complications during pregnancy and fetal size and prematurity to global SA and specific regional signatures across child cortical MRI features.

• Whitmore, Lucy & Beck, Dani (2025). Current challenges and future directions for brain age prediction in children and adolescents. Nature Communications. 16(1). doi: 10.1038/s41467-025-63222-7. Full text in Research Archive Show summary

  Abstract Advancements in computational techniques have enhanced our understanding of human brain development, particularly through high-dimensional data from magnetic resonance imaging (MRI). One notable approach is the brain-age prediction framework, which predicts biological age from neuroimaging data and calculates the brain age gap (BAG), a marker of deviation from chronological age. Most commonly applied to adult samples, this approach is now increasingly used in children and adolescents. However, several considerations must be taken into account when applying brain-age prediction in youth. In this Perspective, we outline important challenges and provide recommendations for researchers as well as future directions for the field.

• Haskell, Erin; Sigmarsdottir, Berglind; Thorisdottir, Ingibjorg Eva; Valborgarson, Audun; Aparicio, Elena Bonilla & Kiviruusu, Olli [Show all 15 contributors for this article] (2025). Adolescent mental health before, during, and after the COVID-19 pandemic in Iceland: a repeated, cross-sectional, population-based study. The Lancet Regional Health - Europe. 53. doi: 10.1016/j.lanepe.2025.101301. Full text in Research Archive Show summary

  Background Adolescents' mental health declined during the COVID-19 pandemic, yet little is known about the long-term outcomes after the pandemic's declassification as a global health emergency (5 May 2023). This study examined changes in adolescent mental health in Iceland from 2016 to 2023, using a bioecological framework to identify risk and protective factors. Methods Youth in Iceland surveys were administered nationwide to 13-15-year-olds in 2016, 2018, 2020, 2021, 2022 and 2023, with an average 75% response rate across the years. The surveys included measures on depressive symptoms, anxiety and hostility (Symptom Checklist-90), parental social support (Perceived Parental Support Scale), screen time, and stress/trauma exposure (Negative Life Events Scale). Stepwise-reduced mixed-effects models assessed the association of age, gender, time and risk/protective factors and their effect on mental health. Multiple imputation addressed missing data, and Bonferroni corrections adjusted for multiple testing. Findings 62,011 adolescents participated: 48.2% female (n = 29,890), 50.0% male (n = 31,002), 1.8% non-binary (n = 1119). Depressive symptoms showed signs of improvement post-pandemic (2023) compared to 2021 (β 0.19, 95% CI 0.13–0.24), yet remained higher than pre-pandemic levels (2016: β −0.38, 95% CI −0.44 to −0.33; 2018: β −0.26, 95% CI −0.31 to −0.20). Anxiety and hostility also increased and remained higher than pre-pandemic levels in 2023 (anxiety: 2016 β −0.29, 95% CI −0.35 to −0.24, 2018 β −0.20, 95% CI −0.26 to −0.15; hostility: 2016 β −0.26, 95% CI −0.31 to −0.20, 2018 β −0.12, 95% CI −0.18 to −0.07). Across all the models examining the predictors from diverse bioecological spheres, low parental social support, high social media use, and bad grades were consistently associated with poor mental health, regardless of mental health outcome and gender. Interpretation The COVID-19 pandemic has had a serious and continuing negative effect on adolescents’ mental health. Targeted interventions are needed to address the increase in mental health problems during the COVID-19 pandemic, with a focus on enhancing parental support and managing screen use.

• Høstmælingen, Andreas Teisner; Nissen-Lie, Helene, Amundsen; Monsen, Jon Trygve; Heinonen, Erkki; Wampold, Bruce E. & Czajkowski, Nikolai Olavi [Show all 9 contributors for this article] (2025). Use of antidepressant medication is associated with slower response to open-ended psychotherapy for depressed patients. Frontiers in Psychiatry. 16. doi: 10.3389/fpsyt.2025.1503848. Full text in Research Archive Show summary

  Objective Depressed patients often experience both symptomatic distress and interpersonal problems. Comorbid personality disorder (PD) has been shown to attenuate the benefits of psychotherapy. Also, antidepressant medication (ADM) may affect the response to psychotherapy. The objective of this study was to investigate changes in depressive symptoms and interpersonal problems for ADM users and non-medicated depressed patients during psychotherapy and follow-up, controlling for comorbid PD. Method Depressive symptoms (SCL-90-R), and interpersonal problems (IIP-64) were assessed on 11 occasions for 166 depressed patients. ADM was used by 50.6% of the sample while 49.4% were unmedicated. Change during treatment and follow-up was assessed with multilevel modeling. We assessed whether ADM and PD predicted differences in symptom development. Results Depressive symptoms significantly reduced at a rate of.05 per month in treatment ( p &lt;.001), corresponding to an effect size of 1.35. Interpersonal problems significantly reduced at a rate of.02 per month during treatment ( p &lt;.001), corresponding to an effect size of.47. There was no significant difference between ADM users and nonmedicated patients at baseline. ADM users had nearly twice as long treatment duration than nonmedicated patients, and ADM users had lower rate of symptom reduction than nonmedicated patients for depressive symptoms and interpersonal problems. There were no differences in rates of change between patients with and without comorbid PD. Conclusion Medicated patients may experience less response to psychotherapy in terms of depressive symptoms and interpersonal problems compared to nonmedicated patients.

• Bjørndal, Ludvig Daae; Ebrahimi, Omid V. & Bauermeister, Sarah (2025). The dynamic interplay between mental health difficulties and the family environment in early adolescence. JCPP Advances. doi: 10.1002/jcv2.70037. Full text in Research Archive Show summary

  Background: Adolescents experiencing mental health problems have an elevated risk of persisting difficulties as they transition into adulthood, stressing the importance of identifying modifiable factors impacting mental health during adolescence. The family environment is recognised as a key influence on adolescent mental health in theory and interventions. Notably, few studies have disentangled within‐person and between‐person effects in relating adolescent mental health and the family environment. Methods: We analysed data from 1067 adolescents across three waves using panel graphical vector autoregressive modelling, separating contemporaneous and temporal within‐person and between‐person associations in relationships between mental health difficulties (i.e., emotional, hyperactivity/inattention, conduct problems) and family‐related factors (i.e., aspects of the general family environment, parent‐child relationships, and sibling dynamics). We also assessed how the different mental health difficulties and family environment factors were themselves interrelated over time. The mean age (in years) was 10.51 at Wave 1, 12.49 at Wave 2, and 14.49 at Wave 3. Results: Emotional symptoms predicted increases in hyperactivity/inattention and more sibling problems over time. Lack of family support and negative feelings towards family were reciprocally related, indicative of a reinforcing loop. Both mental health difficulties and family environment factors exhibited considerable stability. In contemporaneous within‐person associations, mental health difficulties were strongly interrelated, as were aspects of the family environment. Furthermore, conduct problems were linked to externalising behaviours (e.g., fighting with parents, bothering siblings) and emotional symptoms to internalising experiences of family dynamics (e.g., feeling negative towards family, being bothered by siblings). Negative feelings towards family and hyperactivity/inattention were strongly predicted by included variables, while emotional symptoms, fighting with parents, and lacking family support were predictive of other variables. Conclusions: Our findings point to the importance of emotional problems in adolescence, which may contribute to worsened hyperactivity/inattention and more problems with siblings over time, and the interrelatedness of mental health and the family environment. Alleviating internalising problems in affected adolescents may help mitigate development of other mental health difficulties and negative sibling dynamics.

• Roettger, Timo; Askelund, Jo Adrian Dahl; Birkenæs, Viktoria; Bjørndal, Ludvig Daae; Bochynska, Agata & Glaser, Bernt Damian [Show all 13 contributors for this article] (2025). Transparency in epidemiological analyses of cohort data a case study of the Norwegian mother, father, and child cohort study (MoBa). BMC Medical Research Methodology. 25, p. 1–11. doi: 10.1186/s12874-025-02601-6. Full text in Research Archive Show summary

  Background Epidemiological research is central to our understanding of health and disease. Secondary analysis of cohort data is an important tool in epidemiological research but is vulnerable to practices that can reduce the validity and robustness of results. As such, adopting measures to increase the transparency and reproducibility of secondary data analysis is paramount to ensuring the robustness and usefulness of findings. The uptake of such practices has not yet been systematically assessed. Methods Using the Norwegian Mother, Father, and Child Cohort study (MoBa; [23, 24]) as a case study, we assessed the prevalence of the following reproducible practices in publications between 2007–2023: preregistering secondary analyses, sharing of synthetic data, additional materials, and analysis scripts, conducting robustness checks, directly replicating previously published studies, declaring conflicts of interest and publishing publicly available versions of the paper. Results Preregistering secondary data analysis was only found in 0.4% of articles. No articles used synthetic data sets. Sharing practices of additional data (2.3%), additional materials (3.4%) and analysis scripts (4.2%) were rare. Several practices, including data and analysis sharing, preregistration and robustness checks became more frequent over time. Based on these assessments, we present a practical example for how researchers might improve transparency and reproducibility of their research. Conclusions The present assessment demonstrates that some reproducible practices are more common than others, with some practices being virtually absent. In line with a broader shift towards open science, we observed an increasing use of reproducible research practices in recent years. Nonetheless, the large amount of analytical flexibility offered by cohorts such as MoBa places additional responsibility on researchers to adopt such practices with urgency, to both ensure the robustness of their findings and earn the confidence of those using them. A particular focus in future efforts should be put on practices that help mitigating bias due to researcher degrees of freedom – namely, preregistration, transparent sharing of analysis scripts, and robustness checks. We demonstrate by example that challenges in implementing reproducible research practices in analysis of secondary cohort data—even including those associated with data sharing—can be meaningfully overcome.

• Olechowski, Mateusz; Górski, Maciej R.; Joshanloo, Mohsen; Hussain, M. Azhar; Wasiel, Arkadiusz & Yeung, Victoria Wai Lan [Show all 112 contributors for this article] (2025). Cultural religiosity moderates the relationship between being in love and subjective well-being. International Journal of Intercultural Relations. ISSN 0147-1767. 108. doi: 10.1016/j.ijintrel.2025.102227. Full text in Research Archive Show summary

  Previous research indicates that the significance of love varies considerably across cultures. In the present study, we introduce an often-overlooked cultural factor – religiosity – to explore its influence on the relationship between being in love and five dimensions of subjective well-being. We conducted two cross-cultural studies with 31,608 participants from 117 samples across 83 societies. Our findings reveal that, in more religious cultures, being in love is a weaker predictor of well-being compared to more secular cultures in four out of six models. These findings indicate that national context influences the relative importance of various emotions and experiences for well-being, underscoring the need to account for cultural context in research on love.

• Kowal, Marta; Sorokowski, Piotr; Gjoneska, Biljana; Pisanski, Katarzyna; Pfuhl, Gerit & Aguilar, Leonardo [Show all 196 contributors for this article] (2025). Cross-cultural data on romantic love and mate preferences from 117,293 participants across 175 countries. Scientific Data. 12. doi: 10.1038/s41597-025-05365-2. Full text in Research Archive Show summary

  Psychological studies on close relationships have often overlooked cultural diversity, dynamic processes, and potentially universal principles that shape intimate partnerships. To address the limited generalizability of previous research and advance our understanding of romantic love experiences, mate preferences, and physical attractiveness, we conducted a large-scale cross-cultural survey study on these topics. A total of 404 researchers collected data in 45 languages from April to August 2021, involving 117,293 participants from 175 countries. Aside from standard demographic questions, the survey included valuable information on variables relevant to romantic relationships: intimate, passionate, and committed love within romantic relationships, physical-attractiveness enhancing behaviors, gender equality endorsement, collectivistic attitudes, personal history of pathogenic diseases, relationship quality, jealousy, personal involvement in sexual and/or emotional infidelity, relational mobility, mate preferences, and acceptance of sugar relationships. The resulting dataset provides a rich resource for investigating patterns within, and associations across, a broad range of variables relevant to romantic relationships, with extensive opportunities to analyze individual experiences worldwide.

• Gui, Anna; Hollowell, Anja; Wigdor, Emilie M.; Morgan, Morgan J.; Hannigan, Laurie John & Corfield, Elizabeth Claire [Show all 28 contributors for this article] (2025). Genome-wide association meta-analysis of age at onset of walking in over 70,000 infants of European ancestry. Nature Human Behaviour. 9, p. 1470–1487. doi: 10.1038/s41562-025-02145-1. Full text in Research Archive
• Walker, Karen Christina; Specht, Ina O.; Hjortdal, Vibeke; Christesen, Henrik T.; Heitmann, Berit L. & Santorelli, Gillian [Show all 14 contributors for this article] (2025). Circulating 25-Hydroxyvitamin D Levels During Pregnancy and Risk of Congenital Heart Diseases: Multivariable and Mendelian Randomization Analyses Using 3 Birth Cohorts. Journal of the American Heart Association (JAHA). 14(9). doi: 10.1161/JAHA.124.036273. Full text in Research Archive Show summary

  Background: Identifying modifiable risk factors for congenital heart disease (CHD) is important for prevention. Previous studies have reported associations between 25‐hydroxyvitamin D (25(OH)D) in pregnancy and CHD in the offspring. However, these studies contain important methodological limitations. We aimed to investigate 25(OH)D levels during pregnancy in relation to offspring risk of CHD using both multivariable regression (MVR) analysis and Mendelian randomization (MR) analysis. Methods: Data from the ALSPAC (Avon Longitudinal Study of Parents and Children), BiB (Born in Bradford), and MoBa (Norwegian Mother, Father and Child Cohort) studies (N=8722 (77 cases) for MVR analysis, N=74 953 (646 cases) for MR) were used. MVR analysis was adjusted for offspring sex, maternal age, education, body mass index, smoking, alcohol consumption, and parity. One sample MR was performed with weighted genetic risk score for 25(OH)D based on published genome‐wide significant genetic variants. Sensitivity analyses explored the relevance and validity of the genetic risk score. Results were pooled across the 3 cohorts in a meta‐analysis with random effects and consistency between results from the MVR and MR was examined. Results: Pooled results from the adjusted MVR suggested higher maternal pregnancy 25(OH)D associated with lower CHD risk, though the CIs were wide and included the null (odds ratio [OR], 0.79 [95% CI, 0.53, 1.06] per 1 SD higher 25(OH)D). By contrast precise MR results did not support a causal relationship (OR, 0.99 [95% CI, 0.91, 1.07] per 1 SD higher 25(OH)D genetic risk score). Conclusions: We did not find robust evidence supporting an effect of maternal pregnancy 25(OH)D levels on offspring CHD.

• Stänicke, Line Indrevoll; Jessen, Reidar Schei; Staksrud, Elisabeth; Stoilova, Mariya; Graham, Richard & Livingstone, Sonia [Show all 7 contributors for this article] (2025). The Eclipse of Young people’s Life: The Importance of Exploring Engagement in Self-Harm Content Online in Psychotherapy. Journal of Infant, Child, and Adolescent Psychotherapy (JICAP). ISSN 1528-9168. 24(1), p. 54–67. doi: 10.1080/15289168.2025.2450193. Full text in Research Archive
• Askelund, Jo Adrian Dahl; Hegemann, Laura Elizabeth; Allegrini, Andrea G.; Corfield, Elizabeth Claire; Ask, Helga & Davies, Neil Martin [Show all 9 contributors for this article] (2025). The Genetic Architecture of Differentiating Behavioral and Emotional Problems in Early Life. Biological Psychiatry. ISSN 0006-3223. 97(12), p. 1163–1174. doi: 10.1016/j.biopsych.2024.12.021. Full text in Research Archive Show summary

  Background: Early in life, behavioral and cognitive traits associated with risk for developing a psychiatric condition are broad and undifferentiated. As children develop, these traits differentiate into characteristic clusters of symptoms and behaviors that ultimately form the basis of diagnostic categories. Understanding this differentiation process—in the context of genetic risk for psychiatric conditions, which is highly generalized—can improve early detection and intervention. Methods: We modeled the differentiation of behavioral and emotional problems from age 1.5 to 5 years (behavioral problems − emotional problems = differentiation score) in a preregistered study of ∼79,000 children from the population-based Norwegian Mother, Father, and Child Cohort Study. We used genomic structural equation modeling to identify genetic signal in differentiation and total problems, investigating their links with 11 psychiatric and neurodevelopmental conditions. We examined associations of polygenic scores (PGS) with both outcomes and assessed the relative contributions of direct and indirect genetic effects in ∼33,000 family trios. Results: Differentiation was primarily genetically correlated with psychiatric conditions via a neurodevelopmental factor. Total problems were primarily associated with the neurodevelopmental factor and p-factor. PGS analyses revealed an association between liability to attention-deficit/hyperactivity disorder and differentiation (β = 0.11; 95% CI, 0.10 to 0.12) and a weaker association with total problems (β = 0.06; 95% CI, 0.04 to 0.07). Trio-PGS analyses showed predominantly direct genetic effects on both outcomes. Conclusions: We uncovered genomic signal in the differentiation process, mostly related to common variants associated with neurodevelopmental conditions. Investigating the differentiation of early-life behavioral and emotional problems may enhance our understanding of the developmental emergence of different psychiatric and neurodevelopmental conditions.

• Schaps, Valerie; Hansen, Thomas; Nes, Ragnhild Bang & Wahrendorf, Morten (2025). How are location and type of caring associated with the carer’s mental health? Cross-sectional and longitudinal findings from SHARE. European Journal of Ageing. ISSN 1613-9372. 22. doi: 10.1007/s10433-025-00843-3. Full text in Research Archive Show summary

  Research findings on the relationship between caring and health are mixed and call for a more nuanced analysis of the care situation. This study investigates cross-sectional and longitudinal associations between caring and depressive symptoms, considering location and type of care. Data come from the Survey of Health Ageing and Retirement in Europe (SHARE), collected in wave 6 (from 2015 to 2016) and wave 8 (from 2019 to 2020). Cross-sectional data were available for 52.186 respondents in 18 countries. Of these, 18.659 were free of elevated depressive symptoms in wave 6 and were used to investigate incident depression in the longitudinal analyses. We distinguished between personal care, practical help, and paperwork, and were able to compare in-home and outside-home personal care. For both men and women, findings indicate that in-home personal care is associated with an increased risk of reporting and developing depressive symptoms (after controlling for age, country affiliation, education, wealth, employment situation, and functional limitations). Cross-sectional, but not longitudinal, associations were also found for outside-home care in terms of personal care or paperwork, but not for practical help. Additionally, women and disadvantaged population groups were more likely to provide in-home care, but less likely to provide outside care (regardless of the type). Overall, the results highlight that different locations and types of care are associated differently with mental health. Findings also underscore the need for interventions specifically tailored to support disadvantaged populations who provide in-home care, addressing the unique challenges they face.

• Prydz, Monica Beer; Bjørndal, Ludvig Daae; Czajkowski, Nikolai Olavi; Røysamb, Espen & Nes, Ragnhild Bang (2025). Direct and indirect effects of a digital Five Ways to Wellbeing intervention: A network intervention analysis. Behaviour Research and Therapy. ISSN 0005-7967. 191. doi: 10.1016/j.brat.2025.104781. Full text in Research Archive Show summary

  While digital positive psychology interventions demonstrate effectiveness in promoting wellbeing and reducing illbeing in the general population, their pathways of change are relatively underexplored. The wellbeing promotive digital intervention, Five Ways to Wellbeing for All (5waysA), has been shown effective (Cohens’ d effect sizes from .20 to .49) in a large (N = 963) randomized controlled trial (Prydz et al., 2024). In the present study, network intervention analysis (NIA) was applied to identify putative direct and indirect effects linking the 5waysA intervention to a set of wellbeing outcomes. Following the 10-week intervention period, the NIA revealed that only positive emotions on an aggregate level were conditionally dependent on the treatment allocation variable. These findings suggest that the effectiveness of the 5waysA intervention primarily reflects the direct enhancement of positive emotions. Our findings provide insights of potential importance for advancing the theoretical framework of the Five Ways to Wellbeing and other mental health and wellbeing promoting interventions.

• Apsley, Abner T.; Ye, Qiaofeng; Caspi, Avshalom; Chiaro, Christopher; Etzel, Laura & Hastings, Waylon J. [Show all 13 contributors for this article] (2025). Cross-tissue comparison of epigenetic aging clocks in humans. Aging Cell. ISSN 1474-9718. 24(4). doi: 10.1111/acel.14451. Full text in Research Archive
• Shakeshaft, Amy; Mundy, Jessica R.; Pedersen, Emil M.; Dennison, Charlotte A.; Riglin, Lucy & Bragantini, Daniela [Show all 15 contributors for this article] (2025). Long-term physical health conditions and youth anxiety and depression: Is there a causal link? Psychological Medicine. ISSN 0033-2917. 55. doi: 10.1017/S0033291724003271. Full text in Research Archive Show summary

  Background The prevalence of youth anxiety and depression has increased globally, with limited causal explanations. Long-term physical health conditions (LTCs) affect 20–40% of youth, with rates also rising. LTCs are associated with higher rates of youth depression and anxiety; however, it is uncertain whether observed associations are causal or explained by unmeasured confounding or reverse causation. Methods Using data from the Norwegian Mother, Father, and Child Cohort Study (MoBa) and Norwegian National Patient Registry, we investigated phenotypic associations between childhood LTCs, and depression and anxiety diagnoses in youth (<19 years), defined using ICD-10 diagnoses and self-rated measures. We then conducted two-sample Mendelian Randomization (MR) analyses using SNPs associated with childhood LTCs from existing genome-wide association studies (GWAS) as instrumental variables. Outcomes were: (i) diagnoses of major depressive disorder (MDD) and anxiety disorders or elevated symptoms in MoBa, and (ii) youth-onset MDD using summary statistics from a GWAS in iPSYCH2015 cohort. Results Having any childhood LTC phenotype was associated with elevated youth MDD (OR = 1.48 [95% CIs 1.19, 1.85], p = 4.2×10−4) and anxiety disorder risk (OR = 1.44 [1.20, 1.73], p = 7.9×10−5). Observational and MR analyses in MoBa were consistent with a causal relationship between migraine and depression (IVW OR = 1.38 [1.19, 1.60], pFDR = 1.8x10−4). MR analyses using iPSYCH2015 did not support a causal link between LTC genetic liabilities and youth-onset depression or in the reverse direction. Conclusions Childhood LTCs are associated with depression and anxiety in youth, however, little evidence of causation between LTCs genetic liability and youth depression/anxiety was identified from MR analyses, except for migraine.

• Barca, Maria Lage; Aakhus, Eivind; Langballe, Ellen Melbye; Hansen, Thomas; Aunsmo, Ragnhild Holmberg & Selbæk, Geir [Show all 8 contributors for this article] (2025). Depression among older adults in Norway 1995-2019: Time trends, correlates, and future projections in a population study: The HUNT study. PLOS ONE. 20(7). doi: 10.1371/journal.pone.0328413. Full text in Research Archive Show summary

  Objectives: To investigate patterns and correlates of depression among Norwegian older adults (age 70+), 1995-2019, and estimate the number of older adults with depression by 2050. Design: Population-based cross-sectional study. Setting and participants: Three surveys of the Trøndelag Health Study (Norway): HUNT2 (1995-96), HUNT3 (2007-08), and HUNT4 (2017-19). 22,822 home dwellers aged 70 + who participated in at least one of the three surveys. Methods: Depression was defined as scores ≥8 on the depression subscale of the Hospital Anxiety and Depression Scale. Covariates included sex, age, education, marital status, and reported loneliness. Depression prevalence (%) was standardized to the Norwegian population by age, sex, and education for years close to the initial HUNT survey year (1995, 2006, and 2016). Projection of the total number of individuals with depression in the coming decades were estimated. Predictors of depression were analyzed with logistic regression and the potential reduction in depression prevalence by reducing the prevalence of loneliness was estimated. Results: Standardized depression prevalence decreased from 16.7% (HUNT2) to 14.9% (HUNT3), and 11.5% (HUNT4), and was highest among men, the oldest (85+), the lower-educated, and in earlier surveys (all p < 0.001). Living alone was also associated with higher depression prevalence, but only if loneliness was present. While depression rates are falling, we expect the number of depressed individuals to double by 2050 as the population ages. Conclusion and implications: Depression rates among adults aged 70 + decreased by 50% from 1995 to 2019, but less so among the oldest old. The rates were highest among single older men. Despite decreasing prevalence, the number of depressed older adults will increase significantly in the future. Given the major individual and societal costs of depression, this trend is alarming for societies preparing for the challenges posed by population aging. This can, however, be addressed by addressing predictors of depression.

• Bjørndal, Ludvig Daae; Chen, Yufeng; Lu, Donghao; Brikell, Isabell; Kuja-Halkola, Ralf & D'Onofrio, Brian M. [Show all 13 contributors for this article] (2025). Stress Resilience and Risk of Psychiatric Disorders After Childhood Bereavement. JAMA Network Open. p. 1–13. doi: 10.1001/jamanetworkopen.2025.19706. Full text in Research Archive
• Hansen, Heidi Marie Umbach; Røysamb, Espen; Vassend, Olav Mandt; Czajkowski, Nikolai Olavi; Endestad, Tor & Vuoskoski, Jonna Katariina [Show all 8 contributors for this article] (2025). Dimensions of music use motivations: Genetic and environmental underpinnings, and associations with Big Five and Empathy traits. PLOS ONE. 20(8). doi: 10.1371/journal.pone.0329808. Full text in Research Archive Show summary

  People differ in their motivation for seeking musical experiences and these differences appear to be partially attributable to their personality. However, little is known about the role of genetic and environmental factors in shaping individual differences in motivations for music use and their shared etiology with personality. This study investigated, using the classical twin design in a sample of 2611 Norwegian twins, the genetic and environmental architecture of four dimensions of motivations for music use (musical transcendence, emotion regulation, social bonding, and musical identity and expression). We also examined their phenotypic associations, as well as genetic and environmental overlap with general personality traits, including the Big Five and Trait Empathy facets. Additive genetic and unique environmental effects largely accounted for the variation in the four dimensions (heritability 38%−52%, mean = 45%), though univariate analyses of the social bonding dimension indicated common environmental influences for this specific subscale. In line with previous studies, trait-congruent phenotypic associations were found between specific personality traits and music use motives, including facets of negative emotionality and musical emotion regulation. Other facets – particularly aesthetic sensitivity (open-mindedness) and fantasy (trait empathy) – were closely tied to all dimensions. Multivariate biometric modeling of the links between personality traits and motivations for music use revealed that these relationships were primarily driven by correlated genetic factors, with personality traits accounting for 40%−66% of the total genetic variance and 5%−17% of the total environmental variance in the music use motivation dimensions. These findings shed new light on the etiology of dispositional music use and provide a comprehensive baseline for future investigations of associations with personality, mental health, and well-being.

• Allegrini, A.G.; Hannigan, Laurie John; Frach, L.; Barkhuizen, W.; Baldwin, J.R. & Andreassen, Ole [Show all 10 contributors for this article] (2025). Intergenerational transmission of polygenic predisposition for neuropsychiatric traits on emotional and behavioural difficulties in childhood. Nature Communications. 16(1). doi: 10.1038/s41467-025-57694-w. Full text in Research Archive
• Karstoft, Karen-Inge; Bjørndal, Ludvig Daae; Pedersen, Anne Agathe; Korchakova, Nataliia; Power, Séamus A. & Morton, Thomas A. [Show all 9 contributors for this article] (2025). Associations of war exposures, post-migration living difficulties and social support with (complex) PTSD: A cohort study of Ukrainian refugees resettled in Denmark. Social Science and Medicine. ISSN 0277-9536. 376. doi: 10.1016/j.socscimed.2025.118080. Full text in Research Archive
• Kanina, Aleksandra; Sjölander, Arvid; Martini, Miriam I.; Butwicka, Agnieszka; Larsson, Henrik & Hughes, Amanda M. [Show all 11 contributors for this article] (2025). Prenatal exposure to adverse life events and autism and autistic-like traits in children in the Norwegian Mother, Father and Child Cohort Study (MoBa). JCPP Advances. 5(4). doi: 10.1002/jcv2.70002. Full text in Research Archive Show summary

  Background Mothers' experience of adverse life events (ALEs, e.g., divorce, bereavement, injury) during pregnancy has been linked with neurodevelopmental conditions like autism, and related traits like social communication difficulties and repetitive behavior in children. However, both the cumulative association and the underlying mechanism are unclear, and these associations might be confounded by unmeasured genetic or other early environmental factors shared within families. Method This longitudinal population-based cohort study included 114,247 children, born in Norway between 1999 and 2009, who participated in the Norwegian Mother, Father and Child Cohort Study. During week 30 of pregnancy, mothers of 51,940 children (of whom 12,597 were siblings) reported whether they had experienced ALEs. We estimated associations between mothers’ cumulative exposure to and perception of ALE and their children’s clinical diagnosis of autism, and maternal reports on their children's autistic traits at ages 3 and 8 years through the Social Communication Questionnaire (SCQ). Sibling comparisons were conducted to account for unmeasured familial confounding. Results Each additional prenatal ALE was associated with increased adjusted hazard ratios [HR: 1.23, 95% CI: 1.16–1.30] of autism diagnosis, compared to unexposed children. Adjusting for unmeasured familial confounding in sibling comparisons, the association attenuated: HR = 0.53, 95% CI [0.31–0.90]. ALEs perceived as more painful were associated with a 12% elevated likelihood of autism diagnosis [95% CI: 7%–16%], but this association attenuated after sibling comparisons. SCQ scores in children exposed to cumulative prenatal ALE compared to unexposed children were higher at age 3 (β-coefficient: 0.24 (95%CI [0.21–0.27])), but only slightly at age 8 (β-coefficient: 0.07 [95% CI: 0.04–0.10]) with differences nullified in the sibling comparison analysis. Conclusion The association between maternal prenatal exposure to cumulative ALEs and diagnosis of autism and autism-associated traits is likely due to unmeasured familial confounding rather than a direct causal relationship.

• Ebeltoft, Joakim Coleman; Eilertsen, Espen Moen; Cheesman, Rosa Catherine Gillespie; Ayorech, Ziada; Hootegem, Arno Van & Lyngstad, Torkild Hovde [Show all 7 contributors for this article] (2025). The genetic and environmental composition of socioeconomic status in Norway. Nature Communications. 16(1). doi: 10.1038/s41467-025-58961-6. Full text in Research Archive Show summary

  Estimating the contributions of genetic and environmental factors is key to understanding differences in socioeconomic status (SES). However, the heritability of SES varies by measure, method, and context. Here, we estimate genetic and environmental sources of variance and commonality in the ‘big four’ SES indicators. We use high-quality administrative data on educational attainment, occupational prestige, income, and wealth, and employ four family-based and unrelated genotype-based heritability methods, all drawn from the same population-wide cohort of >170,000 Norwegians aged 35-45. By drawing subsamples from a consistent sample and using registry-based data, we reduce differences in estimates due to population characteristics and measurement error. Our results show that genetic variation consistently explains more for educational attainment and occupational prestige. Family-shared environmental contributions explained more for educational attainment and wealth. Our results highlight considerable common influences on the four SES indicators among genetic and shared environmental factors, but not among non-shared environmental factors. Overall, we show how the relative importance of genetic and environmental factors to SES differences in Norway varies by method and type of socioeconomic attainment. This study is a reliable source for comparing heritability methods, and for comparing SES indicators and their genetic and environmental commonality in a social-democratic welfare state.

• Emslander, Valentin; Holzberger, Doris; Ofstad, Sverre Berg; Fischbach, Antoine & Scherer, Ronny (2025). Teacher-Student Relationships and Student Outcomes: A Systematic Second-Order Meta-Analytic Review. Psychological bulletin. ISSN 0033-2909. 151(3), p. 365–397. doi: 10.1037/bul0000461. Full text in Research Archive Show summary

  Teacher–student relationships (TSRs) play a vital role in establishing a positive classroom climate and promoting positive student outcomes. Several meta-analyses have suggested significant correlations between positive TSRs and, for example, academic achievement, motivation, executive functions, and well-being, as well as between negative TSRs that result in behavior problems or bullying. These meta-analyses have differed substantially in TSR–outcome relationships, moderators, and methodological quality, thus complicating the interpretation of these findings. In this preregistered systematic review of meta-analyses plus original second-order meta-analyses (SOMAs), we aimed to (a) synthesize the meta-analytic evidence on relations between TSRs and student outcomes, (b) map influential moderators of these relations, and (c) assess the methodological quality of the meta-analyses. We synthesized over 70 years of educational research across 26 meta-analyses encompassing 119 meta-analytic effect sizes based on approximately 2.64 million prekindergarten and K–12 students. We conducted several three-level SOMAs and found that TSRs had similar large significant relations with eight clusters of student outcomes: academic achievement, academic emotions, appropriate student behavior, behavior problems, executive functions and self-control, motivation, school belonging and engagement, and well-being. The link with bullying was only marginally significant. Our moderator analyses suggested a larger TSR–outcome link for middle and high school students. Although more recent meta-analyses fulfilled more methodological quality criteria, these differences were not associated with TSR–outcome relations. These results map the field of TSR research; present their relations, moderators, and methodological quality in meta-analyses; and show how TSRs are equally important for a wide range of student outcomes and samples.

• Kvalem, Ingela Lundin; Soest, Tilmann von; Sundgot-Borgen, Christine & Dahlgren, Anna Maria Camilla Lindvall (2025). Kosmetisk kirurgi blant kvinner – en tverrsnittsstudie. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 145(1). doi: 10.4045/tidsskr.24.0218. Full text in Research Archive Show summary

  Bakgrunn Undersøkelser fra 2003 og 2008 indikerte at 7–8 % av voksne kvinner i Norge hadde gjennomgått kosmetisk kirurgi. Det foreligger lite oppdatert kunnskap om dette, og hovedmålet med studien var å kartlegge bruk av, ønske om og sosial aksept for kosmetisk kirurgi, samt forskjeller i demografiske og psykososiale faktorer mellom kvinner som har gjennomgått, de som ønsker, og de som ikke ønsker kosmetisk kirurgi. Materiale og metode Et utvalg på 3 071 kvinner i alderen 18 til 60 år ble rekruttert fra panelet til meningsmålingsinstituttet Ipsos/MMI, hvorav 3 055 kvinner ble inkludert i studien. Strukturerte telefonintervjuer ble utført i desember 2022. Resultater Blant deltakerne svarte 526 (17 %) at de hadde gjennomført én eller flere kosmetiske operasjoner. 1 588 (52 %) rapporterte at det var sannsynlig at de ville gjennomføre kosmetisk kirurgi, og 535 (18 %) hadde selv blitt anbefalt kosmetisk kirurgi. Kvinnene som hadde gjennomført eller ønsket kosmetisk kirurgi, hadde lavere utdanningsnivå, var mindre fornøyde med egen kropp og utseende, hadde oftere blitt anbefalt kosmetisk kirurgi, og var oftere på utseendefokuserte sosiale medier, sammenlignet med dem som ikke ønsket kosmetisk kirurgi. Fortolkning Studien indikerte en økning i bruk av kosmetisk kirurgi blant voksne kvinner de siste 20 årene, fra 8 % til 17 %, samt en økning i både ønske om og sosial aksept for kosmetisk kirurgi.

• Clarke, Eden V.; Lilly, Kieren J.; Osborne, Danny; Cone, Deborah Hill; Fluit, Sam & Simionato, Natalia M. [Show all 8 contributors for this article] (2025). A Naturalistic Test of Minority Stress Theory: Examining Social and Psychological Well-Being Trends Across Heterosexual and Sexual Minority Adults from 2009 to 2022. Journal of Sex Research. ISSN 0022-4499. doi: 10.1080/00224499.2025.2458636. Full text in Research Archive
• Ivanova, Anna; Fluit, Sam; Fischer, Nantje; Soest, Tilmann Martin von & Kozák, Michal (2025). Masturbation Trajectories from Late Adolescence into Mid-Adulthood: A Population-Based Longitudinal Study. Journal of Sex Research. ISSN 0022-4499. doi: 10.1080/00224499.2025.2489091. Full text in Research Archive
• Jessen, Reidar Schei; Wæhre, Anne; David, Linda W.; Stänicke, Line Indrevoll & Stänicke, Erik (2025). “It was actually my family and friends who noticed that my voice changed”: An interview study on the experiences of transgender and non-binary youth and young adults three years into medical treatment. International Journal of Transgenderism. ISSN 2689-5269. p. 1–15. doi: 10.1080/26895269.2025.2478498. Full text in Research Archive
• Cheesman, Rosa Catherine Gillespie; Anapaz, Ville; Alten, Sjoerd van; Abdellaoui, Abdel; Porneso, Ralph Pascual Ortiz & Ebeltoft, Joakim Coleman [Show all 16 contributors for this article] (2025). Genetic associations with educational fields. Nature Genetics. ISSN 1061-4036. 57, p. 2997–3006. doi: 10.1038/s41588-025-02391-z. Full text in Research Archive Show summary

  Educational field choices shape careers, wellbeing and the societal skill distribution, yet genetic influences on what people study remain poorly understood. Here we show that genetic factors are associated with educational field specializations using genome-wide association studies (GWASs) across 463,134 individuals from Finland, Norway and the Netherlands (effective n between 40,072 and 317,209). We identified 17 independent genome-wide significant variants linked to 7 of 10 educational fields, with average heritability of 7%. The genetic signal is specific to field choice rather than educational level, persisting after controlling for years of schooling and confounding factors. By examining genetic clustering across specializations, we uncovered two key dimensions: technical versus social and practical versus abstract. We performed GWASs of these components and demonstrated distinct genetic correlations with personality, behavior and socioeconomic status. Our findings demonstrate that genomic research can illuminate ‘horizontal’ stratification, revealing insights into vocational interests and social sorting beyond traditional attainment measures.

• O'Connell, Kevin Sean; Koromina, Maria; Veen, Tracy van der; Boltz, Toni; David, Friederike S. & Yang, Jessica Mei Kay [Show all 313 contributors for this article] (2025). Genomics yields biological and phenotypic insights into bipolar disorder. Nature. ISSN 0028-0836. 639, p. 968–975. doi: 10.1038/s41586-024-08468-9. Full text in Research Archive Show summary

  Bipolar disorder is a leading contributor to the global burden of disease1. Despite high heritability (60–80%), the majority of the underlying genetic determinants remain unknown2. We analysed data from participants of European, East Asian, African American and Latino ancestries (n = 158,036 cases with bipolar disorder, 2.8 million controls), combining clinical, community and self-reported samples. We identified 298 genome-wide significant loci in the multi-ancestry meta-analysis, a fourfold increase over previous findings3, and identified an ancestry-specific association in the East Asian cohort. Integrating results from fine-mapping and other variant-to-gene mapping approaches identified 36 credible genes in the aetiology of bipolar disorder. Genes prioritized through fine-mapping were enriched for ultra-rare damaging missense and protein-truncating variations in cases with bipolar disorder4, highlighting convergence of common and rare variant signals. We report differences in the genetic architecture of bipolar disorder depending on the source of patient ascertainment and on bipolar disorder subtype (type I or type II). Several analyses implicate specific cell types in the pathophysiology of bipolar disorder, including GABAergic interneurons and medium spiny neurons. Together, these analyses provide additional insights into the genetic architecture and biological underpinnings of bipolar disorder.

• Philis, Curtis Edward; Miller, Jeremy K.; Buchanan, Erin M.; Williams, Amanda; Meyers, Chanel & Brown, Elizabeth R. [Show all 50 contributors for this article] (2025). Multi-region investigation of ‘man’ as default in attitudes. PLOS ONE. 20(6), p. 1–19. doi: 10.1371/journal.pone.0323938. Full text in Research Archive Show summary

  Previous research has studied the extent to which men are the default members of social groups in terms of memory, categorization, and stereotyping, but not attitudes which is critical because of attitudes’ relationship to behavior. Results from our survey (N > 5000) collected via a globally distributed laboratory network in over 40 regions demonstrated that attitudes toward Black people and politicians had a stronger relationship with attitudes toward the men rather than the women of the group. However, attitudes toward White people had a stronger relationship with attitudes toward White women than White men, whereas attitudes toward East Asian people, police officers, and criminals did not have a stronger relationship with attitudes toward either the men or women of each respective group. Regional agreement with traditional gender roles was explored as a potential moderator. These findings have implications for understanding the unique forms of prejudice women face around the world.

• Eftedal, Nikolai Haahjem; Eilertsen, Espen Moen; Sunde, Hans Fredrik; Kleppestø, Thomas Haarklau; Ystrøm, Eivind & Czajkowski, Nikolai Olavi (2025). Beyond additive genetic effects: Explaining family resemblance in school performance across millions of pairs of Norwegian relatives. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 122(25), p. 1–9. doi: 10.1073/pnas.2419627122. Full text in Research Archive Show summary

  We investigate the hypothesis that family resemblance on school performance can be fully explained by additive genetic effects and assortative mating. Our sample consists of all schoolchildren who took Norwegian national standardized tests between 2007 and 2019 (N = 936,708). These tests measure aptitude in math and reading comprehension, and are taken the years children turn 10, 13, and 14 y old. We identify millions of pairs of relatives within our sample (82 different kinds, in total), including not only conventional biological relatives such as siblings and cousins, but also relatives-in-law, relatives through adoption, twins, and relatives connected through twins. When fitting models which assume that family resemblance arises solely from additive genetic effects and assortative mating, we find that they describe much of our data well, but that they systematically underestimate the similarity of close relatives (particularly monozygotic twins), maternal relatives, relatives-in-law, and relatives through adoption. We discuss potential explanations for these deviations, including shared-environmental effects, nonadditive genetic effects, and gene–environment interplay.

• Nordmo, Magnus; Sunde, Hans Fredrik; Kleppestø, Thomas Haarklau; Nordmo, Morten; Caspi, Avshalom & Moffitt, Terrie [Show all 7 contributors for this article] (2025). Cognitive Abilities and Educational Attainment as Antecedents of Mental Disorders: A Total Population Study of Males. Psychological Science. ISSN 0956-7976. 36(7), p. 499–513. doi: 10.1177/09567976251347221. Full text in Research Archive Show summary

  The positive relation between mental health and educational attainment is well established, yet the extent to which cognitive abilities influence this gradient or independently predict mental health outcomes remains unclear. In this study, we investigated the association between adolescent cognitive abilities, educational attainment, and adult mental health. Cognitive ability was ascertained in Norwegian military conscript test data (N = 272,351; mean age 17.8 years; males only), whereas mental disorders were ascertained using the Norwegian register of primary care diagnoses received between the age of 36–40. Higher cognitive abilities were associated with a monotonically decreasing risk of developing all the studied mental disorders except bipolar disorder. The association held even when comparing the cognitive abilities of brothers raised in the same family, attesting that cognitive ability and mental disorders are not associated because both arise from the same family background circumstances. Similarly, individuals with higher educational attainment had fewer mental health disorders. The association between low cognitive abilities and the risk of mental disorders was notably stronger in males with low educational attainment, compared to those with high educational attainment. These individuals may be an underutilized target group for mental-disorder prevention.

• Torgalsbøen, Anne-Kari; Mohn, Christine; Larøi, Frank & Czajkowski, Nikolai Olavi (2025). Longitudinal recovery and self-efficacy in first-episode schizophrenia: insights from a 10-year follow-up study. Frontiers in Psychiatry. p. 01–09. doi: 10.3389/fpsyt2025.1588349. Full text in Research Archive Show summary

  Background: Research on clinical recovery rates in first-episode schizophrenia has yielded inconsistent results due to varying definitions of recovery and methodological differences. The longitudinal trajectory of recovery—whether rates improve, decline, or remain stable—remains unclear. Schizophrenia significantly impacts young lives, making it crucial to examine self-efficacy, the belief in one’s ability to manage adversity, and its relationship with clinical recovery. Methods: The Oslo Schizophrenia Recovery study`s repeated assessment design, including twelve clinical evaluations over ten years, is ideal for studying longitudinal recovery. Self-efficacy was measured using the General Perceived Self-Efficacy scale, with data analyzed through linear multilevel models. Twenty-eight well-defined first-episode schizophrenia patients were assessed yearly, using a strict recovery definition (two years of full symptom remission and adequate social/role functioning), with 79% of patients retained from baseline. Results: Recovery rates improved and remained stable, suggesting better outcomes than previously reported. Of the participants, 50% achieved clinical recovery. Recovered individuals showed a sharp increase in self-efficacy within the first year, while non-recovered patients exhibited gradual improvement. The interaction between recovery status and time revealed distinct self-efficacy trajectories, particularly in the first post-onset year. Conclusions: A significant proportion of first-episode schizophrenia patients can achieve clinical recovery. While these positive outcomes are noteworthy, it is important to recognize that recovery paths can vary widely among individuals. Since people with schizophrenia are concerned about their chances of recovery, the results must be shared with patients and their families. While the causal relationship between self-efficacy and recovery remains unclear, they likely influence each other.

• Creasey, Nicole; Schuurmans, Isabel; Tsotsi, Stella; Dafina, Serena; Baltramonaityte, Vilte & Felix, Janine F. [Show all 12 contributors for this article] (2025). Prenatal stress, epigenetically-assessed glucocorticoid exposure at birth, and child psychiatric symptoms: A prospective, multi-cohort study. Psychoneuroendocrinology. ISSN 0306-4530. 175. doi: 10.1016/j.psyneuen.2025.107388. Full text in Research Archive
• Amundsen, Vaarin; Gjesmoe, Amalie; Andreassen, Einar; Bølstad, Evalill; Severinsen, Yvonne & Viana, Karine Porpino [Show all 10 contributors for this article] (2025). Alcohol Use and Parental Socialization of Emotion in a Population-Based Sample. Parenting, science and practice. ISSN 1529-5192. doi: 10.1080/15295192.2025.2465988. Full text in Research Archive
• Hansen, Heidi Marie Umbach; Laeng, Bruno; Vassend, Olav Mandt; Czajkowski, Nikolai Olavi; Endestad, Tor & Danielsen, Anne [Show all 7 contributors for this article] (2025). The role of Big Five personality domains and facets in musical sensibility: a twin study. Scientific Reports. 15(1). doi: 10.1038/s41598-025-95661-z. Full text in Research Archive Show summary

  Musical sensibility can be understood as a propensity to be emotionally and aesthetically engaged by music and may constitute a key feature of a multidimensional definition of musicality. Yet, the nature of this construct is only just beginning to be understood. In a sample of adult Norwegian twins (N = 2592), we aimed to establish whether interindividual variability in musical sensibility may partially be attributable to personality, both in terms of the Big Five personality domains and their lower-order facets, as well as the role of genes and environments. Phenotypic analyses demonstrated that the personality domains of open-mindedness (and the facet aesthetic sensitivity in particular), agreeableness (and the facet compassion), and negative emotionality were all significantly associated with and predictive of musical sensibility. Multivariate biometric twin models further revealed that these relations were driven mainly by genetic influences, accounting for 50–100% of the observed covariance, whereas non-shared environmental influences accounted for the rest. Moreover, genetic correlations of musical sensibility with personality traits were substantial, and particularly strong for open-mindedness, pointing to considerable overlap in the biological mechanisms underlying the two traits. These findings situate musical sensibility within a broader network of psychological dispositions, possibly linked together via common affective systems.

• Sundgot-Borgen, Christine; Sundgot-Borgen, Jorunn; Sølvberg, Nina; Torstveit, Monica Klungland; Mountjoy, Margo & Mathisen, Therese Fostervold (2025). Factors predicting disordered eating and the prevalence of eating disorders in adolescent elite athletes, trained athletes and a reference group: a prospective controlled two-step study. British Journal of Sports Medicine. ISSN 0306-3674. 59(15), p. 1043–1054. doi: 10.1136/bjsports-2024-108808. Full text in Research Archive Show summary

  Abstract Objective To prospectively examine the prevalence of diagnosed eating disorders (ED-diagnosis), ED-symptoms and factors predicting ED-symptoms in three male and female high school student groups: elite athletes, trained athletes and a non-athlete reference group at baseline (T1) and 1-year follow-up (T2). Methods A survey was administered at baseline (T1) (n=1186) and 1-year follow-up (T2) (n=1144) (step-one). Participants classified with ED-symptoms by the Eating Disorder Examination Questionnaire (EDEQ 6.0) at T2 were invited to a diagnostic interview (step-two). Results Prevalence of ED-diagnosis for males and females were 6.9% and 9.3% in elite athletes, 5.9% and 11.2% in trained athletes and 3.0% and 11.9% in references, respectively. No group differences were statistically significant. Male references had more ED-symptoms compared with elite and trained male athletes (EDEQ-global score 0.81 vs <0.55), while elite female athletes had fewer ED-symptoms compared with trained female athletes and female references (EDEQ-global score 1.14 vs >1.59). Trained female athletes increased ED-symptoms over time, whereas elite female athletes consistently had fewer ED-symptoms in comparison. High ED-symptom presentation was predicted by high body mass index and more psychological distress in males, whereas for females, ED-symptoms were predicted by lower resilience, more psychological distress and being a non-athlete reference. Conclusion No statistically significant group differences in the prevalence of ED-diagnosis were observed between elite athletes, trained athletes and a non-athlete reference group. Female elite athletes had fewer ED-symptoms compared with other female groups, and male references had more ED-symptoms compared with male athlete groups. Preventive measures that address psychological resilience and distress should be considered.

• Hegemann, Laura Elizabeth; Eilertsen, Espen Moen; Pettersen, Johanne Hagen; Corfield, Elizabeth Claire; Cheesman, Rosa Catherine Gillespie & Frach, Leonard [Show all 11 contributors for this article] (2025). Direct and indirect genetic effects on early neurodevelopmental traits. Journal of Child Psychology and Psychiatry. ISSN 0021-9630. 66(7), p. 1053–1064. doi: 10.1111/jcpp.14122. Full text in Research Archive Show summary

  Background Neurodevelopmental conditions are highly heritable. Recent studies have shown that genomic heritability estimates can be confounded by genetic effects mediated via the environment (indirect genetic effects). However, the relative importance of direct versus indirect genetic effects on early variability in traits related to neurodevelopmental conditions is unknown. Methods The sample included up to 24,692 parent-offspring trios from the Norwegian MoBa cohort. We use Trio-GCTA to estimate latent direct and indirect genetic effects on mother-reported neurodevelopmental traits at age of 3 years (restricted and repetitive behaviors and interests, inattention, hyperactivity, language, social, and motor development). Further, we investigate to what extent direct and indirect effects are attributable to common genetic variants associated with autism, ADHD, developmental dyslexia, educational attainment, and cognitive ability using polygenic scores (PGS) in regression modeling. Results We find evidence for contributions of direct and indirect latent common genetic effects to inattention (direct: explaining 4.8% of variance, indirect: 6.7%) hyperactivity (direct: 1.3%, indirect: 9.6%), and restricted and repetitive behaviors (direct: 0.8%, indirect: 7.3%). Direct effects best explained variation in social and communication, language, and motor development (5.1%–5.7%). Direct genetic effects on inattention were captured by PGS for ADHD, educational attainment, and cognitive ability, whereas direct genetic effects on language development were captured by cognitive ability, educational attainment, and autism PGS. Indirect genetic effects on neurodevelopmental traits were primarily captured by educational attainment and/or cognitive ability PGS. Conclusions Results were consistent with differential contributions to neurodevelopmental traits in early childhood from direct and indirect genetic effects. Indirect effects were particularly important for hyperactivity and restricted and repetitive behaviors and interests and may be linked to genetic variation associated with cognition and educational attainment. Our findings illustrate the importance of within-family methods for disentangling genetic processes that influence early neurodevelopmental traits, even when identifiable associations are small.

• Sunde, Hans Fredrik; Eilertsen, Espen Moen & Torvik, Fartein Ask (2025). Understanding indirect assortative mating and its intergenerational consequences for educational attainment. Nature Communications. 16(1), p. 1–14. doi: 10.1038/s41467-025-60483-0. Full text in Research Archive Show summary

  We develop a framework for understanding indirect assortative mating and provide updated definitions of key terms. We then develop family models that use partners of twins and siblings to freely estimate the degree of genetic and social homogamy, and account for it when investigating sources of parent-offspring similarity. We applied the models to educational attainment using 1,545,444 individuals in 212,070 extended families in the Norwegian population and Norwegian Twin Registry. Partner similarity in education was better explained by indirect assortment than direct assortment on observed educational attainment, with social homogamy being particularly important. The implied genotypic partner correlation (r = 0.34) was comparable to earlier studies, and higher than expected under direct assortment. About 38% of the parent-offspring correlation (r = 0.34) was attributable to various forms of environmental transmission. Alternative models that assumed direct assortment estimated environmental transmission to be lower, but these did not fit the data well.

• Jessen, Reidar Schei; Wæhre, Anne; David, Linda W.; Stänicke, Line Indrevoll & Stänicke, Erik (2025). Finding Oneself in the Gazes of Others: An Exploration of Subjective Experiences of Gender Among Young Binary Transgender Men. Studies in Gender and Sexuality. ISSN 1524-0657. 26(1), p. 52–69. doi: 10.1080/15240657.2025.2453288. Full text in Research Archive Show summary

  This study explores gender incongruence in young binary transgender men by engaging with historical and recent psychoanalytic theory on transgender identity. Four life-mode interviews were conducted with binary transgender youth assigned female at birth who had recently been referred to medical treatment for gender incongruence. Data were analyzed using interpretative phenomenological analysis (IPA). We developed three major themes: (1) relating to the past—challenging experiences of being ostracized and different from peers, which have been transformed after learning about transgenderism and gender-affirming care, (2) gazes on oneself—the participants’ sense of self emerges from the gazes on themselves from the outside that have been internalized as a male identity on the inside, and (3) gender incongruence—the participants are struggling to unify conflicting gazes on themselves from the outside with the gazes on themselves from the inside, which leads to an estranged relation to their bodies and feelings of shame. We suggest that gender incongruence in young binary transgender men arises when the gazes from the inside and the outside are not sufficiently reconciled. The clinical task is to help young transgender men with their negotiations of gender within their concrete everyday life experiences.

• McGorry, Patrick D.; Hickie, Ian B.; Kotov, Roman; Schmaal, Lianne; Wood, Stephen J. & Allan, Sophie M. [Show all 26 contributors for this article] (2025). New diagnosis in psychiatry: Beyond heuristics. Psychological Medicine. ISSN 0033-2917. 55. doi: 10.1017/S003329172400223X. Full text in Research Archive
• Chen, Si; Ebrahimi, Omid Vakili & Cheng, Cecilia (2025). New Perspective on Digital Well-Being by Distinguishing Digital Competency From Dependency: Network Approach. Journal of Medical Internet Research (JMIR). ISSN 1439-4456. 27. doi: 10.2196/70483. Full text in Research Archive
• Ebrahimi, Omid Vakili; Sandbakken, Ella Marie; Moss, Sigrun Marie; Johnson, Sverre Urnes; Hoffart, Asle & Bauermeister, Sarah [Show all 9 contributors for this article] (2025). Modifiable risk factors of vaccine hesitancy: insights from a mixed methods multiple population study combining machine learning and thematic analysis during the COVID-19 pandemic. BMC Medicine. 23(1). doi: 10.1186/s12916-025-03953-y. Full text in Research Archive Show summary

  Background Vaccine hesitancy, the delay in acceptance or reluctance to vaccinate, ranks among the top threats to global health. Identifying modifiable factors contributing to vaccine hesitancy is crucial for developing targeted interventions to increase vaccination uptake. Methods This mixed-methods multiple population study utilized gradient boosting machines and thematic analysis to identify modifiable predictors of vaccine hesitancy during the COVID-19 pandemic. Predictors of vaccine hesitancy were investigated in 2926 Norwegian adults (Mage = 37.91, 79.69% female), before the predictive utility of these variables was investigated in an independent sample of 734 adults in the UK (Mage = 40.34, 57.08% female). Two independent teams of authors conducted the machine learning and thematic analyses, blind to each other’s analytic procedures and results. Results The machine learning model performed well in discerning vaccine hesitant (n = 248, 8.48% and n = 109, 14.85%, Norway and UK, respectively) from vaccine uptaking individuals (n = 2678, 91.52% and n = 625, 85.15%), achieving an AUC of 0.94 (AUPRC: 0.72; balanced accuracy: 86%; sensitivity = 0.81; specificity = 0.98) in the Norwegian sample, and an AUC of 0.98 (AUPRC: 0.89; balanced accuracy: 89%; sensitivity = 0.83; specificity = 0.97) in the out-of-sample replication in the UK. The mixed methods investigation identified five categories of modifiable risk tied to vaccine hesitancy, including illusion of invulnerability, doubts about vaccine efficacy, mistrust in official entities, minimization of the societal impact of COVID-19, and health-related fears tied to vaccination. The portrayal of rare incidents across alternative media platforms as fear amplifiers, and the mainstream media’s stigmatizing presentation of unvaccinated individuals, were provided as additional motives underlying vaccine reluctance and polarization. The thematic analysis further revealed information overload, fear of needles, previous negative vaccination experiences, fear of not getting healthcare follow-up after vaccination if needed, and vaccine aversion due to underlying (psychiatric) illness (e.g., eating disorders) as motives underlying vaccine hesitance. Conclusions The identified influential predictors were consistent across two European samples, highlighting their generalizability across European populations. These predictors offer insights about modifiable factors that could be adapted by public health campaigns in mitigating misconceptions and fears related to vaccination toward increasing vaccine uptake. Moreover, the results highlight the media’s responsibility, as mediators of the public perception of vaccines, to minimize polarization and provide accurate portrayals of rare vaccine-related incidents, reducing the risk aggravating fear and reactance to vaccination.

• Assary, Elham; Coleman, Jonathan R. I.; Hemani, Gibran; Weijer, Margot P. van de; Howe, Laurence J. & Palviainen, Teemu [Show all 81 contributors for this article] (2025). Genetics of monozygotic twins reveals the impact of environmental sensitivity on psychiatric and neurodevelopmental phenotypes. Nature Human Behaviour. 9, p. 1683–1696. doi: 10.1038/s41562-025-02193-7. Full text in Research Archive Show summary

  Individual sensitivity to environmental exposures may be genetically influenced. This genotype-by-environment interplay implies differences in phenotypic variance across genotypes, but these variants have proven challenging to detect. Genome-wide association studies of monozygotic twin differences are conducted through family-based variance analyses, which are more robust to the systemic biases that impact population-based methods. We combined data from 21,792 monozygotic twins (10,896 pairs) from 11 studies to conduct one of the largest genome-wide association study meta-analyses of monozygotic phenotypic differences, in children, adolescents and adults separately, for seven psychiatric and neurodevelopmental phenotypes: attention deficit hyperactivity disorder symptoms, autistic traits, anxiety and depression symptoms, psychotic-like experiences, neuroticism and wellbeing. The proportions of phenotypic variance explained by single-nucleotide polymorphisms in these phenotypes were estimated (h2 = 0–18%), but were imprecise. We identified 13 genome-wide significant associations (single-nucleotide polymorphisms, genes and gene sets), including genes related to stress reactivity for depression, growth factor-related genes for autistic traits and catecholamine uptake-related genes for psychotic-like experiences. This is the largest genetic study of monozygotic twins to date by an order of magnitude, evidencing an alternative method to study the genetic architecture of environmental sensitivity. The statistical power was limited for some analyses, calling for better-powered future studies.

• Hansen, Thomas; Johansen, Rune; Kirkøen, Benedicte; Stene-Larsen, Kim; Straiton, Melanie Lindsay & Tornes, Ragnhild Agathe [Show all 7 contributors for this article] (2025). Digital bridges to social connection: A systematic review and meta-analysis of digital interventions for loneliness and social isolation. Internet Interventions. ISSN 2214-7829. 41, p. 1–15. doi: 10.1016/j.invent.2025.100856. Full text in Research Archive Show summary

  As loneliness and social isolation emerge as pressing public health concerns, identifying effective interventions is essential. Digital solutions offer flexible, scalable, and cost-effective approaches, yet their effectiveness remains uncertain. This systematic review and meta-analysis assess the impact of randomized controlled trials (RCTs) on digital interventions to reduce loneliness and social isolation. Following PRISMA 2020 guidelines, we searched seven databases and grey literature (2022–) and applied random-effects models to pool effect sizes by intervention type. A total of 40 RCTs involving 6062 participants were included, with one-third focusing on younger individuals. Loneliness was assessed in 36 studies, while eight examined social isolation. Interventions were classified as psychological (k = 25), social (k = 4), activity-based (k = 4), robot-based (k = 4), and social media reduction (k = 5). Psychological interventions—especially those with group or social components—along with group-based activities and robotic pets, were effective in reducing loneliness. In contrast, social contact interventions, self-guided individual activities, and conversational robots showed limited impact. Social media reduction interventions suggested potential benefits, though results were not statistically significant. The evidence base exhibited moderate to high risk of bias, heterogeneity, and limited long-term follow-up. We provide specific recommendations for future interventions and research, including leveraging digital technologies for enhanced personalization, using digital tools for signposting non-digital interventions, systematically comparing digital and non-digital versions of the same intervention, and, most critically, examining the impact of increasingly popular AI-driven and humanlike social chatbots.

• Kjelkenes, Rikka; Fernandez-Cabello, Sara; Voldsbekk, Irene; Holm, Madelene Christin; Dahl, Andreas & Lofthus, Ingvild S. [Show all 10 contributors for this article] (2025). Linking Psychotic-Like Experiences and Brain White Matter Microstructure in Young Women. Brain and Behavior. 15(6), p. 1–12. doi: 10.1002/brb3.70587. Full text in Research Archive Show summary

  Background Psychotic-like experiences (PLE) represent a risk factor for later psychotic disorders and a marker for general mental distress. The connectivity and microstructure of key brain white matter pathways, including fronto–temporal trajectories, have been implicated in psychosis and psychosis-risk. Although sex differences in PLE prevalence and characteristics have been reported, most neuroimaging studies of PLE have primarily included mixed-sex, samples and little research has been carried out in females only. This study examines the associations between PLE and white matter characteristics in young to middle-aged females. Methods We analyzed cross-sectional diffusion magnetic resonance imaging (dMRI) and self-reported data from 661 females aged 9–44 years using the 15-item version of The Community Assessment of Psychic Experiences (CAPE) questionnaire. Associations between CAPE subscales and other psychopathology measures were tested. Using linked independent component analysis (LICA), we decomposed the voxel-wise data from 24 dMRI metrics across five different diffusion models into 10 spatially independent components. We then examined the association between the LICA subject weights and age. Next, we tested for associations between the LICA subject weights and both CAPE total and subscales scores using Bayesian statistics. Results PLE were broadly associated with various domains of psychopathology and psychosocial factors. Moderate evidence emerged for an association between PLE and an LICA component reflecting a broad and complex pattern of diffusivity in major pathways, including the inferior fronto– occipital fasciculus, anterior thalamic radiation, and forceps minor. The persecutory ideations subscale showed the strongest evidence of an effect. Conclusion PLE in young females are associated with a distinct multimodal white matter pattern reflecting microstructural characteristics in key commissural, association, and thalamocortical pathways in young females. The findings support that LICA is a valuable tool for fusing and decomposing advanced dMRI metrics to delineate white matter patterns that show sensitivity to PLE and mental distress.

• Štulhofer, Aleksandar; Fischer, Nantje; Hansen, Thomas; Graham, Cynthia A. & Træen, Bente (2025). Positive Sexual Aging: A Novel Concept and Bi-Country Development of a Brief Measure. Archives of Sexual Behavior. ISSN 0004-0002. 54, p. 2185–2198. doi: 10.1007/s10508-025-03158-7. Full text in Research Archive
• Potočár, Libor; Kozák, Michal; Bøe, Tormod & Soest, Tilmann Martin von (2025). The social gradients in mental health and psychosocial well-being from adolescence to midlife and the mediating role of parenting practices: a national cohort study. Social Science and Medicine. ISSN 0277-9536. 383. doi: 10.1016/j.socscimed.2025.118405. Full text in Research Archive Show summary

  Research investigating social inequalities in mental health and well-being across the life course is scarce. Moreover, a comprehensive examination of underlying pathways linking early life disadvantage to subsequent mental health inequalities is needed. This nationally representative prospective cohort study in Norway followed 3072 individuals from adolescence (mean age 15 years, 1992) to midlife (43 years, 2020). Using latent growth curve modeling, we examined the magnitude and life course development of social gradients in self-reported internalizing problems (symptoms of depression and anxiety), externalizing problems (problematic alcohol use and conduct problems), and psychosocial well-being (loneliness and self-esteem). Family disadvantage in adolescence was assessed by parental educational attainment and living situation. Parenting practices, including behavioral monitoring, warmth, educational investment, social support, and psychological overcontrol, were examined as mediators. Results showed that living with both biological parents was consistently linked with better mental health and psychosocial well-being, with these advantages persisting into midlife. In contrast, lower parental educational attainment was associated with deteriorated psychosocial well-being and externalizing problems during adolescence, but these inequalities diminished with age. Importantly, individuals from advantaged families experienced more nurturing, supportive, and involved parenting, which accounted for a substantial portion of observed mental health disparities during adolescence. Altogether, our findings highlight the importance of early social disadvantage for mental health and well-being across the life course, underscoring the critical role of parenting practices in shaping these trajectories.

• Gu, Yuanjun; Maria-Stauffer, Eva; Bedford, Saashi A.; Zhang, Xinhe; Weir, Elizabeth & Uzefovsky, Florina [Show all 53 contributors for this article] (2025). Polygenic scores for autism are associated with reduced neurite density in adults and children from the general population. Molecular Psychiatry. ISSN 1359-4184. 30, p. 3393–3403. doi: 10.1038/s41380-025-02927-z. Full text in Research Archive
• Hoffart, Asle; Skjerdingstad, Nora Paulsen; Freichel, René; Johnson, Sverre Urnes; Epskamp, Sacha & Ebrahimi, Omid Vakili (2025). Mapping the Dynamics of Generalized Anxiety Symptoms and Actionable Transdiagnostic Mechanisms: A Panel Study. Depression and Anxiety. ISSN 1091-4269. 2025(1). doi: 10.1155/da/1885004. Full text in Research Archive
• MacSweeney, Niamh; Beck, Dani; Whitmore, Lucy; Mills, Kathryn L.; Westlye, Lars Tjelta & Soest, Tilmann Martin von [Show all 8 contributors for this article] (2025). Multimodal Brain Age Indicators of Internalizing Problems in Early Adolescence: A Longitudinal Investigation. Biological Psychiatry: Cognitive Neuroscience and Neuroimaging. ISSN 2451-9022. doi: 10.1016/j.bpsc.2024.11.003. Full text in Research Archive
• Finnemann, Adam; Skjerdingstad, Nora; Speyer, Lydia G.; Zavlis, Orestis; Bartoš, František & Wiers, Reinout [Show all 12 contributors for this article] (2025). Urban-rural differences in anxiety and depression in the UK, New Zealand, and Norway. Journal of Affective Disorders. ISSN 0165-0327. 388. doi: 10.1016/j.jad.2025.119601. Full text in Research Archive
• Bølstad, Evalill; Edvoll, Maud; Solbakken, Ole Andre & Havighurst, Sophie Seychelle (2025). The effectiveness of a parent emotion socialization intervention in Norway. Journal of Applied Developmental Psychology. ISSN 0193-3973. 98. doi: 10.1016/j.appdev.2025.101795. Full text in Research Archive
• Richter, Lydia; Bergunde, Luisa; Karl, Marlene; Jaramillo, Isabel; Weise, Victoria & Mack, Judith T. [Show all 11 contributors for this article] (2025). The associations between paternal postpartum depressive symptoms and testosterone and cortisol levels in hair over the first two years postpartum. Progress in Neuro-psychopharmacology and Biological Psychiatry. ISSN 0278-5846. 137, p. 1–15. doi: 10.1016/j.pnpbp.2024.111245. Full text in Research Archive Show summary

  Background After the birth of a child, also fathers may develop postpartum depression. Altered steroid hormone concentrations are discussed as a possible underlying mechanism, as these have been associated with depressive symptoms in previous studies outside the postpartum period. While higher paternal testosterone levels have been found to protect against paternal postpartum depressive symptoms (PPDS), an association between higher cortisol levels and PPDS has been seen in postpartum mothers, with no comparable studies available on fathers. Objective This study aimed to investigate cross-sectional and longitudinal associations between testosterone and cortisol levels in hair and PPDS over a period of 2 years postpartum. Methods Data from N = 226 fathers, who took part in the endocrine sub-study DREAMHAIR of the longitudinal prospective cohort study DREAM, were used. PPDS were assessed 8 weeks, 14 months, and 24 months after birth using the Edinburgh Postnatal Depression Scale. At the same time, fathers provided 2 cm scalp-near hair samples in which testosterone (HairT) and cortisol (HairF) levels were determined. Cross-sectional and longitudinal associations between HairT, HairF and paternal PPDS were investigated. Results Correlation analyses showed a negative cross-sectional association between HairF levels and paternal PPDS 14 months after birth. A random intercept cross-lagged panel model revealed prospective relationships between paternal PPDS 8 weeks postpartum and HairF 14 months postpartum, and additionally between 14 months and 2 years postpartum in an exploratory model with similarly good model fit. No further significant associations of HairF with paternal PPDS emerged, and none of the analyses with HairT became significant. The overall pattern of results was confirmed when controlling for the influence of batch and storage time on HairT and HairF levels. Conclusion No consistent relationships between HairT or HairF and paternal PPDS emerged in this relatively healthy cohort. In HairF analyses with significant results, lower HairF was associated with more severe PPDS. Longitudinal results imply that altered cortisol secretion may rather follow than precede changes in paternal PPDS. Further research on hormonal changes in PPDS in fathers should consider possible covariates and examine fathers with higher depressive burden, which may help to identify fathers at risk and inform future preventive and interventive approaches.

• Adams, Mark J.; Streit, Fabian; Meng, Xiangrui; Awasthi, Swapnil; Adey, Brett N. & Choi, Karmel W. [Show all 51 contributors for this article] (2025). Trans-ancestry genome-wide study of depression identifies 697 associations implicating cell types and pharmacotherapies. Cell. ISSN 0092-8674. 188(3), p. 640–652.e9. doi: 10.1016/j.cell.2024.12.002. Full text in Research Archive Show summary

  In a genome-wide association study (GWAS) meta-analysis of 688,808 individuals with major depression (MD) and 4,364,225 controls from 29 countries across diverse and admixed ancestries, we identify 697 associations at 635 loci, 293 of which are novel. Using fine-mapping and functional tools, we find 308 high-confidence gene associations and enrichment of postsynaptic density and receptor clustering. A neural cell-type enrichment analysis utilizing single-cell data implicates excitatory, inhibitory, and medium spiny neurons and the involvement of amygdala neurons in both mouse and human single-cell analyses. The associations are enriched for antidepressant targets and provide potential repurposing opportunities. Polygenic scores trained using European or multi-ancestry data predicted MD status across all ancestries, explaining up to 5.8% of MD liability variance in Europeans. These findings advance our global understanding of MD and reveal biological targets that may be used to target and develop pharmacotherapies addressing the unmet need for effective treatment.

• Bårdstu, Silje Kvam; Bølstad, Evalill; John, Oliver P.; Fruyt, Filip De & Soest, Tilmann Martin von (2025). Active During Childhood: Undercontrolled or Extraverted in Late Adolescence? A Longitudinal Study Distinguishing Different Conceptions of Childhood Activity. Journal of Personality and Social Psychology. ISSN 0022-3514. 128(2), p. 456–475. doi: 10.1037/pspp0000543. Full text in Research Archive Show summary

  The role of childhood activity level in personality development is still poorly understood. Using data from a prospective study following 939 children from age 1.5 to 16.5 years, this study examined whether prospective associations of childhood activity with subsequent personality ratings in adolescence differ across two conceptualizations of childhood activity: energetic activity (defined by energy, vigor, and tempo) versus dysregulated activity (distractibility, hyperactivity, and poor self-regulation). We assessed energetic activity development (using latent growth curve modeling) at ages 1.5–8.5 years using the Activity scale from the Emotionality, Activity, and Sociability Temperament Survey, and dysregulated activity at age 8.5 using the Hyperactivity-Inattention scale from the Strengths and Difficulties Questionnaire. We then used these two kinds of activity measures (mother-reported) to predict personality self-descriptions on the Big Five Inventory 8 years later. Personality traits were first regressed on mean levels of energetic and dysregulated activity at age 8.5 years and subsequently regressed on the growth factors of energetic activity development. Results showed mean-level changes in the entire sample as energetic activity decreased by more than 1 SD across childhood (i.e., −0.18 SD per year). Energetic activity at age 8.5 positively predicted higher levels of both the Big Five extraversion domain and the self-discipline facet of conscientiousness at age 16.5. In contrast, dysregulated activity at age 8.5 predicted lower levels of both conscientiousness and agreeableness. The findings advocate for a distinction between energetic and dysregulated activity in temperament and personality theories, addressing inconsistencies in previous research.

• Dardani, Christina; Robinson, Jamie; Jones, Hannah J.; Rai, Dheeraj; Stergiakouli, Evie & Grove, Jakob [Show all 14 contributors for this article] (2025). Immunological drivers and potential novel drug targets for major psychiatric, neurodevelopmental, and neurodegenerative conditions. Molecular Psychiatry. ISSN 1359-4184. 30, p. 4487–4496. doi: 10.1038/s41380-025-03032-x. Full text in Research Archive
• Lund, Ingunn Olea; Hannigan, Laurie; Ask, Helga; Askelund, Jo Adrian Dahl; Hegemann, Laura Elizabeth & Corfield, Elizabeth Claire [Show all 12 contributors for this article] (2025). Prenatal maternal stress: triangulating evidence for intrauterine exposure effects on birth and early childhood outcomes across multiple approaches. BMC Medicine. 23, p. 1–17. doi: 10.1186/s12916-024-03834-w. Full text in Research Archive Show summary

  Background Maternal stress during pregnancy may impact offspring development via changes in the intrauterine environment. However, genetic and environmental factors shared between mothers and children might skew our understanding of this pathway. This study assesses whether prenatal maternal stress has causal links to offspring outcomes: birthweight, gestational age, or emotional and behavioral difficulties, triangulating across methods that account for various measured and unmeasured confounders. Methods We used data from the Norwegian Mother, Father, and Child Cohort Study (MoBa), including maternal reports on prenatal stress at work, at home, and via stressful life events as exposures. Outcomes were children’s birthweight and gestational age, from the Medical Birth Registry of Norway, and maternal reports on early offspring emotional and behavioral difficulties. We assessed associations using four approaches: sibling control analyses, gene-environment interaction analyses, intergenerational Mendelian randomization (MR), and negative control (i.e., postnatal stress) analyses. Results Maternal prenatal stress was observationally associated with offspring lower birthweight (e.g., βwork = − 0.01 [95%CI: − 0.02, − 0.01]), earlier birth (e.g., βwork = − 0.04 [95%CI: − 0.04, − 0.03])), and more emotional (e.g., βevents = 0.08 [95%CI: 0.07, 0.09]) and behavioral difficulties (e.g., βrelationship = 0.08 [95%CI: 0.07, 0.09]) in the full sample (N = 112,784). However, sibling control analyses (N = 36,511) revealed substantial attenuation of all associations after accounting for familial factors. Gene-environment interaction models (N = 76,288) showed no clear evidence of moderation of associations by mothers’ polygenic scores for traits linked to stress sensitivity. Intergenerational MR analyses (N = 29,288) showed no clear evidence of causal effects of maternal plasma cortisol on any offspring outcomes. Negative control exposure analyses revealed similar effect sizes whether exposures were measured prenatally or postnatally. Conclusions Our results indicate that links between prenatal maternal stress and variation in early offspring outcomes are more likely to be confounded than causal. While no observational study can rule out causality, the consistency of our findings across different approaches is striking. Other sources of prenatal stress or more extreme levels may represent intrauterine causal risk factors for offspring development. Nonetheless, our research contributes to identifying boundary conditions of the fetal programming and developmental origins of health and disease hypotheses, which may not be as universal as sometimes assumed.

• Birkenæs, Viktoria; Parekh, Pravesh; Hegemann, Laura Elizabeth; Bakken, Nora Refsum; Frei, Evgeniia & Jaholkowski, Piotr Pawel [Show all 13 contributors for this article] (2025). Youth psychotic experiences: psychometric evaluation and diagnostic associations of the CAPE-16 in adolescents from the Norwegian Mother, Mather and Child Cohort. Journal of Child Psychology and Psychiatry. ISSN 0021-9630. 67(1), p. 27–40. doi: 10.1111/jcpp.70007. Full text in Research Archive Show summary

  Background: Adolescent self-reported psychotic experiences are associated with mental illness and could help guide prevention strategies. Youth report substantially more experiences than adults. However, with large societal changes like the digital revolution and COVID-19 pandemic, existing questionnaires may no longer accurately capture youth experiences. We aimed to determine the ability of the CAPE-16 questionnaire in capturing psychotic experiences across contexts (biological sex and COVID-19 response) and generations, thereby validating important psychometric aspects of the tool in modern adolescents. Methods: We used data from the Norwegian Mother, Father and Child Study (MoBa), a population-based pregnancy cohort. Adolescents responded to the CAPE-16 questionnaire (n = 18,835). For a comparison between age groups, we included adult men from the parent generation who responded to the CAPE-9 (n = 28,793). We investigated the psychometric properties of CAPE-16 through confirmatory factor analyses, measurement invariance testing across biological sex, response before/during the COVID-19 pandemic, and generations (adolescents and fathers), and examined subscale and item-level associations with subsequent registry-based psychiatric diagnoses (average time between CAPE and last registry update: 3.68 ± 1.34 years). Results: Out of 18,835 adolescents, 33.2% reported lifetime psychotic experiences. We confirmed a three-factor structure (paranoia, bizarre thoughts, and hallucinations) and good subscale reliability (ω = .86 and .90). CAPE-16 scores were stable across biological sex and pandemic status. CAPE-9 response patterns were non-invariant across adolescents and adult men, with an item related to digital technology particularly prone to bias. CAPE-16 subscales were associated with subsequent psychiatric diagnoses, especially psychotic disorders. Conclusions: CAPE-16 is a reliable measure of psychotic experiences across sex and a major societal stressor in adolescents. More frequent and distressing experiences increase the risk of subsequent psychiatric diagnoses. Different response patterns between adults and adolescents for items related to digital technology suggest differences in interpretation. Hence, certain items may benefit from revisions.

• Bergen, Elsje van; Zeeuw, Eveline L. de; Hart, Sara A.; Boomsma, Dorret I.; Geus, Eco J. C. de & Kan, Kees-Jan (2025). *Co-Occurrence and Causality Among ADHD, Dyslexia, and Dyscalculia. Psychological Science. ISSN 0956-7976. 36(3), p. 204–217. doi: 10.1177/09567976241293999. Full text in Research Archive
• Austerberry, Chloe; Zayats, Tetyana; Ronald, Angelica; Corfield, Elizabeth Claire; Smajlagic, Dinka & Havdahl, Alexandra [Show all 11 contributors for this article] (2025). Evocative effects of children's education-associated genetics on maternal parenting: results from the Norwegian mother, father and child cohort study. Journal of Child Psychology and Psychiatry. ISSN 0021-9630. 67(2), p. 158–170. doi: 10.1111/jcpp.70025. Full text in Research Archive Show summary

  Background: It has long been hypothesized that increasing heritability with age of cognitive and educational performance is partly attributable to evocative gene–environment correlation. However, this hypothesis has not been widely tested. Methods: We addressed this gap by examining whether children's education polygenic scores (PGSedu) were associated with maternal self-reported positive and literacy-focused parenting when children were 5 years old, and if evoked parenting differences mediated genetic effects on children's educational outcomes (mother-reported at 6–8 years of age), while controlling for parental PGSedu. We also investigated whether maternal reports of children's language at 5 years old were associated with parenting and mediated genetic effects on educational performance. These questions were addressed in a sample of 83,627 parent-offspring trios from the Norwegian Mother, Father and Child Cohort Study, a longitudinal population-based pregnancy cohort. Results: Children's PGSedu were significantly associated with maternal literacy-focused (β = .03, 95% CI [0.01, 0.05], p = .021) but not positive parenting (β = 0.01, 95% CI [−0.02, 0.05], p = .410), and literacy-focused parenting significantly mediated the effects of children's PGSedu on their educational performance (β = 0.01, 95% CI [1 × 10−3, 0.01], p = .023). Children's language was associated with maternal parenting and mediated the effects of children's PGSedu on their educational performance (β = 0.01, 95% CI [3 × 10−3, 0.02], p = .002). Conclusions: These findings support our hypotheses and suggest early language and parenting may be mechanisms implicated in the pathways from children's genetics to their educational outcomes.

• Sunde, Hans Fredrik; Eilertsen, Espen Moen; Kinge, Jonas Minet; Kleppestø, Thomas Haarklau; Nordmo, Magnus & Caspi, Avshalom [Show all 8 contributors for this article] (2025). Parental income and psychiatric disorders from age 10 to 40: a genetically informative population study. Journal of Child Psychology and Psychiatry. ISSN 0021-9630. 67(1), p. 115–126. doi: 10.1111/jcpp.70022. Full text in Research Archive Show summary

  Background Lower parental income is associated with more psychiatric disorders among offspring, but it is unclear if this association reflects effects of parental income (social causation) or shared risk factors (social selection). Prior research finds contradictory results, which may be due to age differences between the studied offspring. Methods Here, we studied psychiatric disorders in the entire Norwegian population aged 10 to 40 years between 2006 and 2018 (N = 2,468,503). By linking tax registries to administrative health registries, we described prevalence rates by age, sex, and parental income rank. Next, we grouped observations into age groups (adolescence, ages 10–20 years; early adulthood, 21–30 years; adulthood, 30–40 years) and applied kinship-based models with extended families of twins and siblings to decompose the parent–offspring correlation into phenotypic transmission, passive genetic transmission, and passive environmental transmission. Results We found that lower parental income rank was associated with higher prevalence of nearly all psychiatric disorders, except for eating disorders, for both men and women at all ages from 10 to 40 years. Comparing the top with the bottom paternal income quartile, the prevalence ratio of any psychiatric disorder was 0.47 among 10-year-olds and decreased to 0.72 among 40-year-olds. The parent–offspring correlation was −.15 in adolescence, −.10 in early adulthood, and −.06 in adulthood. The kinship-based models indicated that phenotypic transmission could account for 39% of the parent–offspring correlation among adolescents (p < .001), but with no significant contribution in early adulthood (p = .181) or adulthood (p = .737). Passive genetic and environmental transmission contributed to the parent–offspring correlation in all age groups (all p's < .001). Conclusions Our findings are consistent with a significant role of social causation during adolescence, while social selection could fully explain the parent–offspring correlation in adulthood.

• Frøyland, Lars Roar; Pedersen, Willy; Enstad, Frøydis & Soest, Tilmann Martin von (2025). School party culture as a driver of cocaine use among Norwegian adolescents: A cross-classified multilevel analysis. Drug and Alcohol Dependence. ISSN 0376-8716. 271. doi: 10.1016/j.drugalcdep.2025.112627. Full text in Research Archive Show summary

  Background: Adolescent substance use typically occurs within peer contexts and is influenced by characteristics of neighborhoods and the cultural environments of the schools adolescents attend. This study aimed to (i) examine variation in cocaine use among adolescents in Oslo, Norway, based on neighborhood of residence and high school affiliation; (ii) assess the significance of school-based party cultures; and (iii) identify individual-level correlates. Methods: The study used data from the Young in Oslo 2023 survey, which collected information from a population-based sample of senior high school students (n = 9741) residing in 95 neighborhoods and attending 25 schools. Participants completed e-questionnaires with information on cocaine use, neighborhood and school affiliation, school-based party cultures, sociodemographic variables, and potential correlates of cocaine use. The data were analyzed using cross-classified multilevel models (CCMM). Results: Of all adolescents, 9.3 % had used cocaine in the previous year. A CCMM including neighborhood and school showed an intraclass correlation coefficient (ICC) of 0.004 for neighborhood and 0.106 for school, indicating that 10.6 % of the variance in cocaine use was linked to school affiliation, while neighborhood variations were negligible. Including school party culture decreased the ICC for school to 0.055, suggesting this measure accounted for half the school-level variance. Further adjustments for individual-level correlates reduced the ICC to 0.028. The most significant individual factors were male gender, alcohol intoxication, and peers use of illicit drugs. Conclusions: Certain youth milieus characterized by heavy-drinking boys and school-based party cultures increased cocaine use. Targeting these environments may be effective in prevention work.

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• Pedersen, Willy (2025). Rusmidlenes skjønnhet og smerte. Cappelen Damm Akademisk. ISBN 9788202816025. 264 p. Full text in Research Archive

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• Ystrom, Eivind; Timpe, Clara Marie Fides & Jole, Oda van (2027). Sosial ulikhet i Norge og barns psykiske utvikling - en megakobling. Full text in Research Archive
• Eftedal, Nikolai Haahjem (2026). For Clark’s Consideration: Genotypic Population Stratification and Non-Additive Genetic Effects. Econ Journal Watch. 23(2), p. 545–553. Full text in Research Archive Show summary

  In his book, To Have and Have Not: The Determinants of Social Status in England, 1600-2026, Gregory Clark argues that a simple model with genetic transmission and assortative mating is sufficient to explain why socio-economic outcomes tend to run in families. Additionally, he provides a collection of arguments against the idea that environmental effects are important contributors to the similarities in outcomes he documents within extended families. Here, I raise two criticisms of Clark’s explanatory framework, and for each criticism suggest ways to mitigate it without introducing environmental effects. First, I criticize the framework for requiring that mates are highly correlated on unobserved traits that are highly heritable and highly genetically correlated with the outcome to be explained. I here suggest allowing for genotypic population stratification. Second, I criticize the framework for underestimating the importance of zygosity for the similarity of twins. As a fix for this, I suggest incorporating non-additive genetic effects.

• Eftedal, Nikolai Haahjem; Lyu, Xuanyu & Keller, Matthew C. (2026). The island model of assortative mating: Assortment through segregation and selective migration. Full text in Research Archive Show summary

  In a sample of 180,194 genotyped norwegians, we have correlations on polygenic scores for both height and educational attainment for 446,779 pairs of relatives, across 20 categories. There are 7 categories of biological relatives and 13 categories of relatives-in-law, connected by increasingly long chains of sibling, parent/child and marriage links, going out as far as six links. For height PGIs, we find that the pattern of correlations aligns well with a simple model of direct phenotypic assortment. For educational attainment, however, PGI correlations between distant in-laws are much too high for direct assortment. And models with indirect assortment on an unobserved trait can fit these data only if this trait is very highly correlated between mates and siblings. We present an alternative mechanism for assortative mating, where mating only occurs within segregated sub-populations, and where movements between sub-populations are uncommon and phenotype dependent. Through simulations, we show that such a model of assortment, which we name “the island model”, can account for our set of PGI correlations without the need for extreme assumptions about an unobserved assortment phenotype. Additionally, the model is consistent with recent studies of migration patterns within nations, showing that movements between rural and urban areas correlate with EA4 PGIs. Implications for behavioral genetic models assuming standard phenotypic assortment are discussed. And so are various properties of this island model, such as equilibrium conditions, and the consequences of sub-population specific shared-environmental effects.

• Nes, Ragnhild Bang (2026). Hverdagsglede som helsekapital. Full text in Research Archive
• Nes, Ragnhild Bang; Røysamb, Espen; Hansen, Thomas & Nilsen, Thomas Sevenius (2026). Norge på 6. plass i Verdens lykkerapport 2026 - FHI. doi: https:/www.fhi.no/nyheter/2026/norge-pa-6.-plass-i-verdens-lykkerapport-2026. Full text in Research Archive Show summary

  FN lanserer World Happiness Report 19. mars. For niende år på rad er befolkningen i Finland den mest fornøyde i verden, foran Danmark og Island. Norge ligger i år på en 6. plass etter de øvrige nordiske landene – og Costa Rica. Afghanistan ligger nederst på listen.

• Nes, Ragnhild Bang (2026). World Happiness Report 2026: Status Norge. Full text in Research Archive
• Nes, Ragnhild Bang; Røysamb, Espen; Czajkowski, Nikolai Olavi & Prydz, Monica Beer (2026). Digital Wellbeing Promotion in the General Population: Effects, Mechanisms, and Long-Term Outcomes of the Five Ways to Wellbeing for All Intervention. Full text in Research Archive Show summary

  Introduction The global rise in mental health problems and compromised wellbeing highlights the need for scalable and cost-effective wellbeing interventions. The Five Ways to Wellbeing for All (5waysA) is a digital adaptation of the UK’s Five Ways to Wellbeing framework, promoting wellbeing through five activity domains: connect, be active, take notice, keep learning, and give. Delivered via two webinars and SMS reminders over ten weeks, the 5waysA program aims to enhance wellbeing and reduce psychological distress in the general population. Methods A large-scale randomized controlled trial (N = 969) and subsequent secondary analyses were conducted in Norway. Self-reported life satisfaction, flourishing, positive emotions, anxiety, and depression were assessed pre-, mid-, and post-intervention. Analyses included multilevel modeling, mediation analysis, and network intervention analysis (NIA). A 12-month follow-up study with synthetic control comparison examined long-term effects. Findings Compared to waiting-list controls, participants in the intervention group reported significantly greater improvements in wellbeing (life satisfaction, flourishing, positive emotions) and reductions in anxiety and depressive symptoms (Cohen’s d = 0.20–0.49), with larger effects among those with most pre-intervention symptoms. Mediation analyses indicated that engagement in the Five Ways activities partially explained these effects, with a clear dose–response relationship between activity engagement and wellbeing outcomes. NIA revealed that increased positive emotions represented the main direct pathway, linking the intervention to improved wellbeing. Long-term follow-up demonstrated sustained gains in life satisfaction at 12 months (d = 0.28), exceeding simulated population-level controls (d = 0.17). Conclusions The 5waysA program effectively promotes wellbeing and reduces distress through accessible, evidence-based activities. Its digital, low-cost format, and durable effects make it a promising large-scale strategy for population-level mental health promotion and positive psychological functioning.

• Nes, Ragnhild Bang (2026). #60 Blir vi lykkeligere av penger? - Sunn Økonomi | Acast. Full text in Research Archive Show summary

  Listen to #60 Blir vi lykkeligere av penger? from Sunn Økonomi. Gjør penger oss lykkelige? I denne episoden har jeg med psykolog og lykkesforsker Gunvor Marie Dyrdal, som har doktorgrad i positiv psykologi - og vi dykker ned i forskningen på penger og lykke. Vi gir deg 8 konkrete hverdagsvaner somforskning viser faktisk gjør oss lykkeligere.

• Nes, Ragnhild Bang (2026). Fem grep for et litt lykkeligere 2026 - Av-og-til. [Internet]. Av og til. Full text in Research Archive Show summary

  Oppdag de fem «lykke-knepene» fra lykkeforsker Ragnhild Bang Nes. Bli lykkeligere i hverdagen med konkrete øvelser og forskningsbaserte grep.

• Nes, Ragnhild Bang (2026). – God livskvalitet er en motor. [Internet]. Forskerforum. Full text in Research Archive Show summary

  Lykkeforsker ved Folkehelseinstituttet Ragnhild Bang Nes mener et godt liv bør være en menneskerett.

• Nes, Ragnhild Bang (2026). Happy You. Full text in Research Archive
• Nes, Ragnhild Bang (2026). Happy Nordics. Full text in Research Archive
• Nes, Ragnhild Bang (2026). – Når gledene oppstår, kan vi like gjerne kjenne på dei - NRK. [Journal]. NRK. Full text in Research Archive Show summary

  Dersom du ikkje følger med, er det lett å gå glipp av kvardagsgleder. Bjarte har trena på å legge merke til dei.

• Smajlagic, Dinka; Sunde, Hans Fredrik; Valenza-Troubat, Noemie; Kelly, Kristen; Lyu, Xuanyu & Sapin, Emmanuel [Show all 12 contributors for this article] (2026). Estimating assortative mating using haplotype-specific polygenic scores across physiological, psychological, and social traits in the Norwegian MoBa Cohort. doi: https:/s3.amazonaws.com/ClubExpressClubFiles/971921/documents/BGA_2026_Final_Program_1883376854.pdf?AWSAccessKeyId=AKIA6MYUE6DNCQ7GISON&Expires=1790839847&response-content-disposition=inline%3B%20filename%3DBGA_2026_Final_Program.pdf&Signature=nfauyWIWzAanx8Du1HeYli1Hi0Q%3D. Full text in Research Archive
• Madhavan, Vaishnavi K; Demange, Perline Aline Delle; Ayorech, Ziada; Hottenga, Jouke Jan; Bartels, Meike & Ystrom, Eivind [Show all 8 contributors for this article] (2026). Bipolar Disorder and Education: Deciphering a Complex Relationship using Genetic and Sibling Differences. doi: https:/s3.amazonaws.com/ClubExpressClubFiles/971921/documents/BGA_2026_Final_Program_1883376854.pdf?AWSAccessKeyId=AKIA6MYUE6DNCQ7GISON&Expires=1790839847&response-content-disposition=inline%3B%20filename%3DBGA_2026_Final_Program.pdf&Signature=nfauyWIWzAanx8Du1HeYli1Hi0Q%3D. Full text in Research Archive
• Demange, Perline Aline Delle (2026). Beyond trio: genetic effects in the extended family. Full text in Research Archive
• Demange, Perline Aline Delle (2026). Beyond trio: genetic effects in the extended family. Full text in Research Archive
• Demange, Perline Aline Delle; Akingbuwa, Wonuola; Cheesman, Rosa Catherine Gillespie & Ystrom, Eivind (2026). A Genomic Test of Goodness-of-Fit: Using Personality Polygenic Indices to Model Parent–Child Fit during Development. Full text in Research Archive
• Demange, Perline Aline Delle; Cheesman, Rosa Catherine Gillespie; Akingbuwa, Wonuola & Ystrom, Eivind (2026). A Genomic Test of Goodness-of-Fit: Using Personality Polygenic Indices to Model Parent–Child Fit. Full text in Research Archive
• Tabori, Mia; Enander, Hilda; Ystrom, Eivind & Demange, Perline Aline Delle (2026). To What Extent Does Early Temperament Predict Symptoms of Anxiety and Depression in Adolescence? A Sibling Design. Full text in Research Archive
• Ofstad, Sverre Berg; Peng, Qiyuan; Ebeltoft, Joakim; Bjørndal, Ludvig Daae; Rayner, Christopher & Ayorech, Ziada [Show all 10 contributors for this article] (2026). PGI-by-Environment interactions: practical guidelines for robust research. Full text in Research Archive
• Demange, Perline Aline Delle (2026). Cognitive, Non-Cognitive, and Genetics: Perline Demange on Skills, Schooling, and Psychopathology. Full text in Research Archive
• Soest, Tilmann von & Potočár, Libor (2026). Å vokse opp med foreldre som er sammen, har betydning lang inn i voksen alder. [Journal]. Aftenposten. Full text in Research Archive Show summary

  Forskerne fulgte over 3000 nordmenn fra de var rundt 15 til 43 år. De fant noen tydelige spor etter foreldrenes betydning.

• Soest, Tilmann von (2026). Dette hjelper mot ensomhet. [Internet]. nrk.no. Full text in Research Archive Show summary

  Nesten hele livet har Svein Arild Johnsen vært farlig ensom. Så fant han løsningen ekspertene hyller.

• Ystrom, Eivind & Torvik, Fartein Ask (2026). How to study GxE in schools. Full text in Research Archive
• Ystrom, Eivind; Demange, Perline Aline Delle; Cheesman, Rosa Catherine Gillespie; McAdams, Thomas Andrew; Eilertsen, Espen Moen & Timpe, Clara Marie Fides [Show all 8 contributors for this article] (2026). Child Personality Polygenic Indices and Parental Distress: Evidence of Active Gene-Environment Correlations and Interactions from Parent–Offspring Trios. doi: https:/osf.io/fwaqp/overview. Full text in Research Archive Show summary

  Child temperament and personality are conjectured to affect parental distress, and there are findings supporting such transactions. Yet, to date, there is no evidence for such evocative gene-environment correlations using exogenous within-family offspring genetic variation. Using 30 000 parent–offspring genotyped trios from the Norwegian Mother, Father and Child Cohort (MoBa), we test how child personality polygenic indexes (PGIs) independently affect maternal and paternal mental distress across the life course (age 16-60). The second longstanding hypothesis is that such child-to-parent transactions are non-additive due to gene-environment interactions. We will reveal the scope of this by estimating the expansion of within-person-timepoint parental mental distress over child personality PGIs. The third longstanding hypothesis is that the evocative effect is dependent on the parental personality, or the “goodness-of-fit”. We will examine moderation by parental Big Five PGIs to test if the effect of a child’s personality on parent depression depends on the parent’s own personality predispositions. This genetically controlled approach provides a novel and robust test of child- evoked effects across the life course. Results for both mothers and fathers will be presented, highlighting the power of child PGIs as a new tool to reveal intergenerational influences on parental mental distress.

• Ystrom, Eivind (2026). Disentangling Direct and Indirect Genetic Effects on Complex Traits: Insights from Two Large-Scale Family Studies. doi: https:/bga.org/docs.ashx?id=1781704. Full text in Research Archive
• Ystrom, Eivind; Ayorech, Ziada; Bjørndal, Ludvig Daae; Timpe, Clara Marie Fides; Cheesman, Rosa Catherine Gillespie & Eilertsen, Espen Moen [Show all 8 contributors for this article] (2026). Child Personality Polygenic Indices and Parental Distress: Evidence of Active Gene- Environment Correlations and Interactions from Parent–Offspring Trios. doi: https:/bga.org/docs.ashx?id=1781704. Full text in Research Archive
• Ystrom, Eivind (2026). Da Mette og Helle ble gravide, ble de en snakkis blant helsepersonell. [Journal]. Aftenposten. Full text in Research Archive Show summary

  Dette er helt tilfeldig og ganske usannsynlig. Men de eneggede tvillingene Mette og Helle Bugge Bergsund (36) har selv fått hvert sitt par eneggede tvillinger i løpet av tre måneder.

• Ystrom, Eivind (2026). Are You Mostly Noise? Eivind Ystrøm on the Genetics of Personality. doi: https:/www.podbean.com/ew/pb-x24tj-1a9abb6. Full text in Research Archive Show summary

  Personality psychologists were doing behavior genetics way before it was cool. In this episode, Rafael and Aysu sit down with Eivind Ystrøm, personality psychologist at the University of Oslo, to talk about what personality actually is, how heritable it turns out to be, and why the field was so far ahead of the rest of the social sciences in taking genetics seriously. They also dig into one of the most provocative findings in the field: the so-called "gloomy prospect" — the idea that a large chunk of what makes you you may come down to essentially random, non-systematic events that even siblings growing up in the same household don't share. What does this mean for the search for specific environmental causes of personality? And more importantly — what is the mysterious mutation that Eivind thinks he may have?

• Ystrom, Eivind & Ivanova, Anna (2026). Do reproductive factors shape depression stability? Early menarche, endometriosis and PMS in longitudinal registry data. doi: https:/2026.ehps.net/wp-content/uploads/2026/08/ehps26_final_program_27_08-1.pdf. Full text in Research Archive Show summary

  Background: Menstrual and gynaecological conditions may increase depression risk, but it is unclear whether they relate to onset versus persistence. Methods: 85,637 women aged 14 to 72 from the Norwegian Mother, Father and Child Cohort Study (MoBa) contributed with 18,415,809 person-months of patient registry data (2006–2023) on primary-care depression diagnosis. Early menarche (before age 12), endometriosis, and Premenstrual Syndrome (PMS) was recorded by questionnaire. Log-binomial regression was used to estimate risk ratios (RR) for population average effects and conditioned on prior-month depression to additionally test condition*prior-depression (stability) interactions and condition*age interactions. Results: Depression was prevalent in 26.3% of women across the 18-year observation period and incident within 1.18% of the person-months. Early menarche, endometriosis, and PMS predicted higher depression risk RR=1.22 (95%CI 1.15-1.29), 1.19 (95%CI 1.04-1.36), and 1.68 (95%CI 1.61-1.75). Conditioning on prior month depression status, main effects were for early menarche RR=1.21 (95%CI 1.15-1.28), endometriosis RR=1.19 (95%CI 1.04-1.35), and PMS remained RR=1.70 (95%CI 1.63-1.77); indicating associations were primarily with transitions into depression rather than persistence. Early menarche RR=0.83 (95%CI 0.79-0.88), endometriosis RR=0.83 (95%CI 0.72-0.95), and PMS RR=0.59 (95%CI 0.56-0.61) all contributed to lower stability of depression. Furthermore, early menarche gave a diminishing risk for depression with older age. Conclusions: Early menarche, endometriosis, and PMS mark elevated depression burden. However, this appears to happen primarily through increased transitions into depression rather than chronicity. Hence, early age of menarche, endometriosis, and PMS may help identify women eligible for preventive mental health interventions rather than being fixed markers of life-course depression risk.

• Ystrom, Eivind (2026). No Link Between Acetaminophen in Pregnancy and Autism, a Study Finds. [Journal]. The New York Times. doi: https:/www.nytimes.com/2026/01/16/health/tylenol-autism-acetaminophen-study.html. Full text in Research Archive Show summary

  The review looked at more than three dozen studies and found no evidence that acetaminophen increased the risk of neurodevelopmental disorders in children.

• Ystrom, Eivind & Madsen, Ole Jacob (2026). Fritt hjemme, strengt på skolen. [Internet]. forskning.no. Full text in Research Archive Show summary

  Dagens foreldre skaper problemer på skolen, ifølge lærere. Professor mener vi overdriver effekten av foreldrestiler.

• Ystrom, Eivind (2026). Ny studie tilbakeviser Trumps Paracet-teori. [Internet]. tv2. Full text in Research Archive Show summary

  USAs president påstod at risikoen for utvikling av autisme økte ved mors inntak av paracetamol.

• Evje, Jacob (2026). Mental health and social relationships in sexual minority youth in Norway ​. Full text in Research Archive
• Evje, Jacob (2026). Mental health, wellbeing, and social challenges in sexual minority youth in Norway ​. Full text in Research Archive
• Qin, Qi; Demange, Perline Aline Delle; Eilertsen, Espen Moen; Cheesman, Rosa Catherine Gillespie & Ystrom, Eivind (2026). How Schools and Neighborhoods Shape the Translation of Polygenic Personality Indices into Academic Outcomes. Full text in Research Archive Show summary

  The Big Five personality traits are robust predictors of individual differences in academic outcomes, yet the mechanisms through which they shape the outcomes remain unclear. Building on our prior work showing contextual moderation of non-cognitive polygenic indices (PGI), we hypothesize that personality traits likewise do not exert uniform influences across contexts. Instead, their effects on academic outcomes emerge through dynamic interactions with the social and economic environments in which individuals develop. Recent GWAS on Big Five personality traits enable the construction of PGIs that quantify the individual-level genetic propensities, and are largely independent of the environment and minimize reverse causality. Using data from ~32,000 trios in the Norwegian Mother, Father, and Child Cohort Study (MoBa) linked to national school and residential registries, we apply multilevel models to investigate how personality-related PGIs contribute to students’ grade point average (GPA), and how these associations vary across latent school and neighborhood contexts. We further test the extent to which the measured socioeconomic status aggregates at the school and neighborhood level interact with individual liability in personality traits. This work aims to provide a comprehensive framework for understanding how individual propensities for personality become developmentally expressed into academic outcomes within real-world contextual ecologies.

• Peng, Qiyuan; Rietveld, Cornelius A.; Ystrom, Eivind; Zachrisson, Henrik Daae; Havdahl, Alexandra & Cheesman, Rosa Catherine Gillespie (2026). Does Universal Childcare Affect Early Child Development? Full text in Research Archive
• Ofstad, Sverre Berg; Demange, Perline Aline Delle; Ayorech, Ziada; Valstad, Mathias & Ystrom, Eivind (2026). Temporal Trends in the Severity and Impairment of Childhood and Adolescent ADHD: A Population-Wide Genetic Study in Norway. Full text in Research Archive Show summary

  By calculating family genetic risk scores for the entire for the entire Norwegian population for birth years 1992-2019, ages 6-16 (N ≈ 1.5M) we show that the reduction in functional impairment over time is largely attributed to a diagnostic expansion of less genetically severe cases. Those who are diagnosed today have lower levels of genetic risk, while simulatenously, there has been no change in the relationship between GPA at age 16 and genetic risk for ADHD.

• Bjørndal, Ludvig Daae; Valstad, Mathias; Eilertsen, Espen Moen; Ayorech, Ziada; Ofstad, Sverre Berg & Salvatore, Jessica E. [Show all 8 contributors for this article] (2026). Peer effects contribute to psychiatric disorder risk: A population-wide study. Full text in Research Archive
• Bjørndal, Ludvig Daae (2026). Disentangling overlapping and unique contributions to wellbeing. Full text in Research Archive
• Ofstad, Sverre Berg; Demange, Perline Aline Delle; Ayorech, Ziada; Valstad, Mathias & Ystrom, Eivind (2026). Temporal Trends in the Severity and Impairment of Childhood and Adolescent ADHD: A Population-Wide Genetic Study in Norway. Full text in Research Archive Show summary

  By calculating family genetic risk scores for the entire for the entire Norwegian population for birth years 1992-2019, ages 6-16 (N ≈ 1.5M) we show that the reduction in functional impairment over time is largely attributed to a diagnostic expansion of less genetically severe cases. Those who are diagnosed today have lower levels of genetic risk, while simulatenously, there has been no change in the relationship between GPA at age 16 and genetic risk for ADHD.

• Fang, Yuan; Ystrom, Eivind; Eftedal, Nikolai Haahjem; Edvoll, Maud Clemson; Folstad, Siri Hausland & Røysamb, Espen [Show all 10 contributors for this article] (2026). Socioeconomic Differences in Student Mental Health Following a Nationwide Curriculum Reform. Full text in Research Archive
• Soest, Tilmann von (2026). I dag - Nyhetsmorgen - NRK Radio. [Radio]. NRK P2. Full text in Research Archive
• Edvoll, Maud Clemson; Folstad, Siri Hausland; Eftedal, Nikolai Haahjem; Poornikoo, Mehdi; Fang, Yuan & Ystrom, Eivind [Show all 11 contributors for this article] (2026). Conference poster; A Norwegian curriculum reform: Effects for 10th graders’ academic performance. Full text in Research Archive
• Fandrem, Hildegunn; Nygaard, Egil & Pedersen, Cathrine (2026). Webinar om FoL (04.02.2026) – HeaLS og LIFE: Refleksjoner om det tverrfaglige temaet Folkehelse og livsmestring. Full text in Research Archive
• Pedersen, Cathrine; Nygaard, Egil; Sundgot-Borgen, Christine & Daza, Viviana (2026). Refleksjonsopplegg om FoL – HeaLS og LIFE: Folkehelse og livsmestring i skolen. Full text in Research Archive
• Vanvik, Marthe Gallefoss; Nygaard, Egil & Pedersen, Cathrine (2026). Refleksjoner og forskningsfunn om Folkehelse og livsmestring. Full text in Research Archive
• Nygaard, Egil (2026). Teaching health and life skills: A good idea, but does it make a difference? Full text in Research Archive
• Soest, Tilmann von (2026). Dagsrevyen - NRK TV. [TV]. NRK 1. Full text in Research Archive Show summary

  Sommerjobb

• Soest, Tilmann von (2026). – Send barna i arbeid før idretten tar dem! – Aftenposten Podkast. doi: https:/www.aftenposten.no/podkast/ap/episode/138654. Full text in Research Archive Show summary

  De som jobber tidlig i ungdomsårene, lyser det lang vei av, mener Aftenpostens skribent. Norske forskere har undersøkt nettopp dette. Har det noe å si? Med spaltist Per Asbjørn Risnes og forsker ved OsloMet og professor ved Universitetet i Oslo Tilmann von Soest. Foto: Heiko Junge, NTB

• Vu, Dinh Hung; Izotova, Anastasia & Fluit, Sam (2026). Beyond the rainbow: Visibility, belonging, and the politics of queer inclusion. doi: https:/www.oslopride.no/events/ph26-beyondrainbow. Full text in Research Archive
• Espseth, Luca Dalen; Evje, Jacob & Fluit, Sam (2026). Sam Fluit and Jacob Evje about trans peoples experience in Europe - Trans Norge | Podcast. Full text in Research Archive Show summary

  Jacob Evje won the "verdt å vite" award for his Masters that compared the experience of transpeople with cisgender LGB people in Europe. In this episode you meet him and his supervisor Sam Fluit. We talk about the findings, but also about how it is to do research on queer topics this days. And Luca are sorry about all the swearing he commits in this episode :) More about the price: https://www.sv.uio.no/om/aktuelt/vag-a-vite/intervjuer/2023/vag-a-vite-diskriminering-vold-mot-transpersoner-psi.html

• Trivigno, Franco & Røysamb, Espen (2026). The Aristotelian Happiness Scale. Full text in Research Archive
• Tamnes, Christian Krog (2026). Hjerneutvikling og betydningen av tidlig livsstress. Full text in Research Archive
• Demange, Perline Aline Delle (2025). Beyond trio: genetic effects in the extended family. Full text in Research Archive
• Demange, Perline Aline Delle (2025). Beyond trio: genetic effects in the extended family. Full text in Research Archive
• Yang, Tianfang; Eftedal, Nikolai Haahjem; Valstad, Mathias; Reichborn-Kjennerud, Ted; Ystrom, Eivind & Czajkowski, Nikolai Olavi (2025). The lifespan impact of personality disorder on marital outcome: a Norwegian population study. Full text in Research Archive
• Czajkowski, Nikolai Olavi; Gustavson, Kristin & Ystrom, Eivind (2025). When Dracula Takes the PID-5: What Can We Learn from Psychometric Exploration of Data Simulated Using Large Language Models. Full text in Research Archive Show summary

  Several recent studies have demonstrated that large language models (LLMs) are able to simulate responses to surveys in ways that mimic observed characteristics of data from real human samples (Argyle, 2023). Since LLMs are trained on a sizeable proportion of all text produced by humans, it is reasonable to expect that they capture a deep understanding of human personality traits. Consequently, analysing data simulated by LLM’s may enable new ways to study psychological constructs and develop psychometric instruments. In this exploratory study, we used the GPT programming interface (API) to prompt the model to generate responses for 300 well-known literary characters across several instruments related to pathological and normative personality traits. This included the PID-5, the Structured Interview for DSM-5 Personality Disorders (SIDP), the Big Five Inventory-2 (BFI-2), and the IPIP-300. Characters were drawn from a wide range of literary traditions, genres, and historical periods. For each instrument, GPT-4o was instructed to adopt the voice and perspective of the character and provide item-level responses using standard Likert-style scales. Our goal was twofold: first, to assess whether the factor structures and inter-scale correlations observed in the simulated data resembled those from real-world samples; and second, to explore whether the same data might suggest novel trait constellations or latent domains not fully captured by existing instruments. Together, these analyses offer a proof of concept for using LLMs in hypothesis generation and instrument development.

• Ystrom, Eivind (2025). Forsker | Utdanning.no. [Internet]. utdanning.no. Full text in Research Archive Show summary

  – Du må stå opp hver dag og faktisk ha lyst til å drive med forskning, forteller Eivind.

• Ystrom, Eivind (2025). Paracetamol under graviditet forårsaker ikke autisme eller ADHD. [Journal]. VG. Full text in Research Archive Show summary

  Norsk studie av 100 000 barn viser ingen årsakssammenheng.

• Ystrom, Eivind (2025). FHI beroliger: Ingen påvist sammenheng mellom paracetamol hos gravide og autisme hos barn. [Journal]. Sykepleien. doi: https:/sykepleien.no/2025/11/fhi-beroliger-ingen-pavist-sammenheng-mellom-paracetamol-hos-gravide-og-autisme-hos-barn. Full text in Research Archive
• Ystrom, Eivind (2025). Fagprat på fredag med Eivind Ystrøm: Sammenhengen mellom genetikk og skoleprestasjoner - Senter for spesialpedagogisk forskning og inkludering (SpedAims). Full text in Research Archive Show summary

  De fleste kjenner til at utfordringer som dysleksi, matematikkvansker og ADHD ofte har en arvelig komponent. Men det er mindre intuitivt at også hvordan vi presterer i fag som norsk og matematikk generelt kan være påvirket av genetiske faktorer gjennom arvbare trekk – ikke bare av sosial bakgrunn. I denne fagpraten presenterer Eivind Ystrøm, professor i personlighetspsykologi og leder for genetikkgruppen ved PROMENTA Research Centre (GeoGen), ny kunnskap om hvordan arv og miljø virker sammen i barns utvikling. Ystrøm forsker på hvordan genetiske og miljømessige faktorer former tidlig sosioøkonomisk utvikling og psykisk helse, blant annet gjennom slektskapsstudier og molekylærgenetiske analyser. Forskningen hans omfatter også «genetic nurture» – hvordan foreldres arvelige egenskaper påvirker barns utvikling, selv når barna ikke arver de samme genene – og hvordan genetiske effekter varierer på tvers av skoler og nærmiljøer.

• Fang, Yuan; Ystrom, Eivind; Eftedal, Nikolai Haahjem; Poornikoo, Mehdi; Edvoll, Maud & Folstad, Siri Hausland [Show all 11 contributors for this article] (2025). Differential Effects of a Nationwide Curriculum-Based Intervention on Student Mental Health: The Role of Socioeconomic Status. doi: 10.17605/OSF.IO/3J6FY. Full text in Research Archive
• Ystrom, Eivind (2025). Writing and Publishing: Reflections from JCPP Advances Editors (Eivind Ystrøm). [Internet]. The Association for Child and Adolescent Mental Health. doi: 10.13056/acamh.13851. Full text in Research Archive Show summary

  In this video from the Writing and Publishing: Reflections from JCPP Advances Editors series, Professor Eivind Ystrøm discusses how unstructured thinking time can lead to creative scientific insights. He reflects on using dialectic reasoning and narrative techniques drawn from film to engage readers and shape research arguments. Drawing on personal habits and storytelling, he shares how self-imposed constraints can support productivity and encourages early-career researchers to view the review process as a constructive dialogue. Learning Objectives 1. Recognise how unstructured time and everyday routines can foster research creativity. 2. Understand how dialectic reasoning and narrative techniques can be used to engage readers. 3. Reframe the peer review process as a dialogue with editors and reviewers.

• Valstad, Mathias; Eftedal, Nikolai Haahjem; Yang, Tianfang; Reichborn-Kjennerud, Ted; Ystrom, Eivind & Czajkowski, Nikolai Olavi (2025). Epidemiology of personality disorders in Norway, 2010 to 2022. Full text in Research Archive
• Pileberg, Silje & Hansen, Heidi Marie Umbach (2025). Tvillingstudie: Er det genetisk å bli berørt av musikk? [Internet]. Forskning.no. Full text in Research Archive Show summary

  Personlighetstyper kan ha mye å si, viser ny forskning.

• Evje, Jacob (2025). Sexual Orientation and Gender Identity in UngData - A National Sample of Norwegian Youth. Full text in Research Archive
• Ystrøm, Eivind & Nordeng, Hedvig Marie Egeland (2025). Paracetamol i svangerskapet. Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 145(14), p. 1164–1164. doi: 10.4045/tidsskr.25.0645. Full text in Research Archive
• Nygaard, Egil (2025). Implementering av Folkehelse og livsmestring i skole. doi: https:/www.uio.no/om/samarbeid/skole/fagped-dag/. Full text in Research Archive
• Nygaard, Egil (2025). Folkehelse og livsmestring i skolen – effekter, praksis og kompetanseutvikling. doi: https:/www.uv.uio.no/ils/om/aktuelt/arrangementer/skolelederdagen/. Full text in Research Archive
• Nygaard, Egil (2025). Public health and life skills in schools – effects and practice. doi: https:/www.med.uio.no/imb/english/research/groups/public-health-nutrition/events/cancer-prevention-school-interventions.html. Full text in Research Archive
• Soest, Tilmann von (2025). Pønsj - NRK Radio. [Radio]. NRK P3. Full text in Research Archive Show summary

  Hvordan er det å være ung i Norge når det kommer til rus, sex og karriere? Det har vår gjest Tilmann von Soest forsket på.

• Krogshus, Kristian Green; Bjertness, Espen; Czajkowski, Nikolai Olavi; Rodriguez-Cano, Ruben & Nes, Ragnhild Bang (2025). Study protocol for 5Ways@School – An implementation and effectiveness trial of a school-based wellbeing intervention in 16 schools in Norway. doi: 10.1177/14034948251370109. Full text in Research Archive Show summary

  Aims: This study aims to assess the effectiveness and implementation of the 5Ways@School curriculum-based intervention in Norwegian schools. The intervention builds on the Five Ways to Wellbeing framework, and promotes five action domains: connect with others, be physically active, take notice, keep learning, and give. The study objectives include assessing the intervention’s acceptability, appropriateness, feasibility, fidelity, and cost, as well as its impact on students’ wellbeing and mental health. Methods: The study is a hybrid effectiveness–implementation trial using mixed methods. It is a longitudinal, two-armed, non-randomized, controlled study involving students in grades 5 to 10 (ages 10 to 16). The primary outcomes are the intervention’s acceptability and feasibility, and its effectiveness on students’ wellbeing. Data collection includes web-based questionnaires for students and teachers, and qualitative interviews with teachers. Quantitative data will be analysed using multilevel regression models and network intervention analysis, while qualitative data will be analysed using thematic analysis. Conclusions: The study aims to provide insights into the implementation and effectiveness of the wellbeing-promoting 5Ways@School intervention. The findings could inform the optimization of the 5Ways@School and other future school-based interventions, and thereby contribute to the wellbeing of children and young people. The study’s strengths include its real-life school setting and mixed methods approach, while limitations include its non-randomized design. Trial registration: ClinicalTrials.gov, ID NCT06144502.

• Czajkowski, Nikolai Olavi; Eilertsen, Espen Moen; Valstad, Mathias; Eftedal, Nikolai Haahjem & Ystrøm, Eivind (2025). A Bayesian Framework for Zygosity Classification and Heritability Estimation Using Nationwide Registry Data. Full text in Research Archive
• Ystrøm, Eivind (2025). Intevju om helseråd til gravide. [TV]. Tv2 Nyhetskanalen. Full text in Research Archive
• Porneso, Ralph Pascual Ortiz; Havdahl, Alexandra; Eilertsen, Espen Moen & Ystrøm, Eivind (2025). Genetic Non-Additivity Reveals Variants in Complex Traits. doi: https:/geneforum.ee/wp-content/uploads/2025/09/Gene-Forum-Poster-Abstract-book.pdf. Full text in Research Archive Show summary

  Background: The contribution of non-additive genetic variation in human traits is nil for dominance, small for epistasis and, theory suggests, minimal for gene-environment interaction. Evidence from behavioral genetics indicates genetic interactions play a role in cognitive traits, and recent genome-wide association studies (GWAS) on height and BMI have identified single nucleotide polymorphisms (SNPs) involved in interactions. This study is a first step to uncover the molecular mechanisms behind gene-gene and gene- environment interactions and, in part, bridge the gap in the missing heritability problem. Study question: Are there SNPs associated with complex traits plasticity? Methods: We used a non-linear mixed effects framework to concurrently estimate SNPs’ mean (i.e. additive) and within individual variability (i.e. non-additive) effects on height and BMI at 6, 8 and 12 months (N=~45,000) and Math and Reading scores at grades 5, 8 and 9 (N=~65,000) from the Norwegian Mother Father and Child cohort (MoBa). We compared our models against a newly developed pipeline, trajGWAS, which restricts discovery to variants with linear within subject (WS) variance effects. Our approach relaxes this restriction. In addition, we investigated whether time-varying effects overlap with non- additive effects. Main results: We found putative “plasticity” variants with linear and non-linear effects. We provide within-individual variability summary statistics for height, BMI, Math and Reading. We found SNP time-varying effects explain ~1% of non-additive effects on average but found no overlap. Limitations: At present, our pipeline runs only using multiple cores and takes a considerable amount of compute hours.

• Porneso, Ralph Pascual Ortiz; Havdahl, Alexandra; Eilertsen, Espen Moen & Ystrøm, Eivind (2025). Non-additive genetic effects and complex traits plasticity. Full text in Research Archive Show summary

  Genome-wide association studies (GWAS) on educational attainment and related outcomes have succeeded at identifying hundreds to thousands of genetic variants with small additive effects using measures collected at a single time point. Recently, GWAS leveraging measures collected at multiple time points have found novel genetic associations, suggesting the presence of previously undetected time-specific variants. We hypothesized that a subset of these variants may be involved in gene-by-gene or gene-by-environment interaction. In the present study, we expanded the GWAS framework by estimating genetic effects on the residual variance. We used non-linear mixed effects (NLME) and double generalized linear models (DGLM) to concurrently estimate mean and within individual variance effects on academic performance in Math and Reading at grades 5, 8 and 9 in ~65,000 children from the Norwegian Mother Father and Child cohort (MoBa). We compared our models against a newly developed pipeline, trajGWAS, which restricts variant discovery to those with log-linear within subject (WS) variance effects. Our approach does not impose this restriction and found variants with non-linear variance effect. We replicated findings from other variance-based approaches that non-additive effects co-occur with mean effects. We decorrelated these effects and provide summary statistics for Math and Reading. This study is a first step to better understanding gene-by-gene and gene-by-environment interactions and shed light on the genetic correlates and potential mechanisms involved in complex trait plasticity.

• Demange, Perline Aline Delle (2025). Beyond trio: genetic effects in the entire extended family. Full text in Research Archive
• Eilertsen, Espen Moen; Ayorech, Ziada Ng'ombo Laurel; Cheesman, Rosa Catherine Gillespie & Ystrøm, Eivind (2025). Et mangfold av ulikhet: Fra økonomi til gener. Full text in Research Archive
• Ayorech, Ziada Ng'ombo Laurel & Ystrøm, Eivind (2025). Genes, Providers, and Depression: Expanding the Scope of Psychiatric Genetic Epidemiology to the Patient–Clinician Relationship. Full text in Research Archive
• Ayorech, Ziada Ng'ombo Laurel & Ystrøm, Eivind (2025). Reflections of an early career researcher. Full text in Research Archive
• Fluit, Sam; Evje, Jacob & Lervik, Martin (2025). Bisexual erasure. Full text in Research Archive Show summary

  Selv om bifile utgjør den største gruppen blant skeive, blir de ofte oversett, fornektet eller misforstått – både i den skeive bevegelsen, i historien, akademia og media. I sin mest ekstreme form innebærer dette det som kalles bi erasure, eller bifil usynlighet: en påstand om at biseksualitet ikke eksisterer, og at personer som identifiserer seg som bifile egentlig er enten heterofile eller homofile. Slike forestillinger gir grobunn for stereotype oppfatninger, som at bifile er forvirret, i fornektelse eller – som med bifile menn – egentlig er homofile som “bare” trenger tid til å “bestemme seg”. Dette fenomenet henger tett sammen med bifobi. Selv om holdningene ikke alltid manifesteres på en uttalt eller uttrykkes på en aggressiv måte, bidrar de til usynliggjøring og til store utfordringer for bifile, som ofte opplever å bli marginalisert både i samfunnet og i LGBTQ+-miljøet.

• Fluit, Sam & Bjerke, Ylva Lie (2025). Mai er internasjonal onanimåned: – Å masturbere har store helsegevinster – Dagsavisen. [Journal]. Dagsavisen. Full text in Research Archive Show summary

  Stipendiat Sam Fluit og kollegaene har forska på nordmenns onanivaner. Det er store forskjeller mellom menn og kvinner, men en ting er klinkende klart: Vi gjør det alle sammen.

• Fluit, Sam & Vollan, Mette (2025). Forskere med ny studie om onani: Store forskjeller på kvinner og menn - NRK. [Internet]. NRK. Full text in Research Archive
• Lyu, Xuanyu & Keller, Matthew (2025). Correlations between relatives in law on polygenic scores. Full text in Research Archive
• Ofstad, Sverre Berg; Tan, Tony & Andersson, Björn (2025). Comparing Elective Subject Difficulty Using a Joint Item Response Theory Model. Full text in Research Archive
• Ofstad, Sverre Berg; Demange, Perline Aline Delle; Torvik, Fartein Ask; Cheesman, Rosa Catherine Gillespie; Qin, Qi & Ystrøm, Eivind (2025). Using within-family polygenic indexes to examine sex-specific gene-environment interaction on GPA. Full text in Research Archive
• Fang, Yuan & Nygaard, Egil (2025). Differential Effects of a Nationwide Curriculum-Based Intervention on Student Mental Health: The Role of Socioeconomic Status. Full text in Research Archive
• Ystrøm, Eivind (2025). Genes as environments – intergenerational transmission of mental health. Full text in Research Archive
• Ystrøm, Eivind (2025). Intergenerational transmission of mental health in the Norwegian Mother, Father and Child Cohort study. Full text in Research Archive
• Ystrøm, Eivind (2025). Parent-Child Fit for Physical Education: Variance Modeling Reveals Independent Pathways. Full text in Research Archive
• Ystrøm, Eivind (2025). There has never been a cause and effect relationship established between Tylenol/Paracetamol/Acetaminophen and autism. [Internet]. Instagram. doi: https:/www.instagram.com/reel/DO8Ln00DGyO/?utm_source=ig_web_copy_link&igsh=MzRlODBiNWFlZA%3D%3D. Full text in Research Archive Show summary

  Acetaminophen is considered the only safe over the counter option for pain or fever for pregnant people. My morning fact check.

• Ystrøm, Eivind (2025). Debate Flares Over an Unproven Link Between Tylenol and Autism. [Journal]. The New York Times. Full text in Research Archive Show summary

  Studies over the last decade of acetaminophen use in pregnancy — including a recent scientific review — have yielded mixed results but have not found a causal connection.

• Ystrøm, Eivind (2025). Trump links Tylenol with autism despite evidence it's safe. [TV]. CNN International. doi: https:/uio-my.sharepoint.com/:v:/g/personal/eivindy_uio_no/Ee-39d2grOxEvlwMibPt0YcBGi8cenLBv5Ctc1Y-m9t0Kw?e=q6537F. Full text in Research Archive
• Ystrøm, Eivind (2025). Norsk forsker om Trumps paracetamol-påstand: - Kan bli alvorlig. [Internet]. tv2.no. Full text in Research Archive Show summary

  - Jeg blir bekymret av uttalelsene fordi Paracet er det mest anbefalte medikamentet å bruke når en har feber under graviditeten, sier forsker Eivind Ystrøm.

• Cheesman, Rosa Catherine Gillespie; Zachrisson, Henrik Daae & Bailey, Drew (2025). Gene-environment interplay and childcare decisions. Full text in Research Archive
• Cheesman, Rosa Catherine Gillespie (2025). Sociogenomics keynote, The Winter School on Inequality and Social Welfare Theory. Full text in Research Archive
• Peng, Qiyuan; Rietveld, Cornelius A. (Niels); Cheesman, Rosa Catherine Gillespie; Ystrøm, Eivind & Havdahl, Alexandra (2025). Causal Intergenerational Transmission of Education in Norway. Full text in Research Archive
• Peng, Qiyuan; Eilertsen, Espen Moen; Cheesman, Rosa Catherine Gillespie; Rietveld, Cornelius A. (Niels); Ystrøm, Eivind & Havdahl, Alexandra (2025). Parental Influence on Children's Educational Achievements: Analysing Direct and Indirect Genetic Effects through Trio-GCTA. doi: https:/www.sv.uio.no/psi/english/research/news-and-events/events/conferences/2025/genetics-and-social-sciences-conference--2025.html. Full text in Research Archive
• Peng, Qiyuan; Pettersen, Johanne Hagen; Sunde, Hans Fredrik; Rietveld, Cornelius A. (Niels); Cheesman, Rosa Catherine Gillespie & Demange, Perline Aline Delle [Show all 11 contributors for this article] (2025). Intergenerational Transmission of Education in Norway: A Triangulation Approach. Full text in Research Archive
• Peng, Qiyuan; Pettersen, Johanne Hagen; Sunde, Hans Fredrik; Rietveld, Cornelius A. (Niels); Cheesman, Rosa Catherine Gillespie & Demange, Perline Aline Delle [Show all 11 contributors for this article] (2025). Intergenerational Transmission of Education in Norway: A Triangulation Approach. Full text in Research Archive Show summary

  The intergenerational transmission of education is a critical topic in social science. Substantial empirical evidence shows that children of highly educated parents often achieve higher levels of academic success than those of less-educated parents (Blanden et al., 2024; Björklund and Salvanes, 2011). Both environmental and genetic factors contribute to the association between parental and offspring educational attainment. However, existing empirical research often conflates these effects due to methodological differences and data limitations, making the results challenging to interpret and sometimes yielding conflicting conclusions (Atav et al., 2024). These limitations restrict insights to intergenerational correlations rather than establishing causal effects. Our study addresses this gap by employing a triangulation approach, integrating multiple methods with distinct strengths and biases to examine whether parental education causally impacts offspring’s educational achievement. Specifically, by leveraging parent-child trios’ register data from Statistics Norway and genetic data from the Norwegian Mother, Father, and Child Cohort Study (MoBa), we apply multivariable regression analysis, entropy balancing, adoption design, and within-family Mendelian randomization to explore the causal relationship between parental educational attainment and offspring’s educational achievement (grade point average, GPA) in Norway. Our preliminary findings suggest a causal effect of parental educational attainment on offspring’s academic success during adolescence, with variations between maternal and paternal influences and differential effects by offspring sex. By isolating genetic confounders, this study enhances our understanding of the causal pathways in intergenerational educational transmission, offering valuable insights for addressing educational inequalities.

• Porneso, Ralph Pascual Ortiz; Havdahl, Alexandra; Eilertsen, Espen Moen & Ystrøm, Eivind (2025). Genetic non-additivity reveals variants in complex traits plasticity. Full text in Research Archive Show summary

  In human complex traits, the contribution of non-additive relative to additive genetic variation is nil (dominance) to small (genetic interactions) which makes variant discovery difficult to achieve (Hivert, 2018). Even with larger samples, gene-gene and gene-environment interaction studies face several technical challenges (e.g. greater multiple testing burden, collecting and modelling correlated factors, etc) that impede progress in uncovering biological insights behind trait plasticity . We work around these issues by concurrently modelling the effect of single nucleotide polymorphisms (SNPs) on trait level, which shifts the distribution, and variability, which generates heteroscedasticity (unequal variance across genotype levels) resulting in the spreading out of phenotypic values around a mean. This approach does not require explicit interaction terms to be fitted to the data thereby lessening both computational complexity and multiple testing burden encountered by more traditional approaches. We estimate SNP effects on trait level (additive) and variability (non-additive) using a longitudinal heteroscedastic mixed effects model that assume uncorrelated variance components. In total, we found 25 lead putative plasticity SNPs (i.e. 2 for infant length, 11 for BMI, 5 for math and 7 for reading) of which 5 (1 for infant length and 4 for BMI) were previously reported in epistatic or gene-environment interaction in independent studies. We show that non-additive, time-varying and additive effects are correlated with each other across all 4 traits, indicating additive genetic variation captures SNP interaction effects. Our findings provide SNP-based evidence that non-additive genetic variation contributes to complex traits including height.

• Kvarberg, Paal Fredrik Skjørten & Liu, Jinrui (2025). Necessary Conditions in Lay Attributions of Well-being. Full text in Research Archive
• Liu, Jinrui; Nes, Ragnhild Bang; Vittersø, Joar; Teulings, Irene Johanna Elisabeth & Røysamb, Espen (2025). How Good is Feeling Good? Full text in Research Archive
• Chegeni, Razieh & Mohn, Ella Bakken (2025). Tuller med traumer: – Så drøyt at det er lættis. [Journal]. tv2.n0. doi: https:/www.tv2.no/nyheter/innenriks/tuller-med-traumer-sa-droyt-at-det-er-laettis/17464149/. Full text in Research Archive
• Ayorech, Ziada Ng'ombo Laurel; Cheesman, Rosa Catherine Gillespie; Demange, Perline Aline Delle; Eilertsen, Espen Moen; Valstad, Mathias & Ystrøm, Eivind (2025). How the importance of family history and gender for receiving a depression diagnosis varies over GP’s. Full text in Research Archive
• Ayorech, Ziada Ng'ombo Laurel (2025). Common misconceptions in Social Science Genetics. Full text in Research Archive
• Ayorech, Ziada Ng'ombo Laurel (2025). Beyond the trio: Broadening the relationships we study to obtain new insights for improving mental health and wellness. Full text in Research Archive
• Ayorech, Ziada Ng'ombo Laurel; Cheesman, Rosa Catherine Gillespie; Demange, Perline Aline Delle; Eilertsen, Espen Moen & Ystrøm, Eivind (2025). Leveraging family-based data reveals gene-environment interplay in life course depression. Full text in Research Archive
• Rayner, Chris; Mcadams, Tom; Havdahl, Alexandra; Ystrøm, Eivind & Ayorech, Ziada Ng'ombo Laurel (2025). A repeated measures GWAS in relatives: detecting age-specific genetic effects on maternal depression. Full text in Research Archive
• Ayorech, Ziada Ng'ombo Laurel & Ystrøm, Eivind (2025). Social Media as a Communication Tool. Full text in Research Archive
• Beck, Kathryn Christine; Reisel, Liza & Torvik, Fartein Ask (2025). Forskere er uenige om fleksibel skolestart. [Journal]. Kilden. Full text in Research Archive Show summary

  Opptakssystemet favoriserer de eldste skolebarna, slår forsker fast. Er fleksibel skolestart løsningen?

• Beck, Dani (2025). Early life adversity and the developing brain. Full text in Research Archive
• Tamnes, Christian Krog (2025). Consistency is key - Reaction time variability as a marker of neurocognitive development and attention problems. Full text in Research Archive
• MacSweeney, Niamh; Toenders, Yara J. & Tamnes, Christian K. (2025). Neuroimaging insights into adolescent depression risk and development. Nature Mental Health. 3(7), p. 779–779. doi: 10.1038/s44220-025-00453-z. Full text in Research Archive
• Demange, Perline Aline Delle (2025). Beyond trio: genetic effects in the entire extended family. Full text in Research Archive
• Demange, Perline Aline Delle; Eilertsen, Espen Moen & Ystrøm, Eivind (2025). Beyond trio: genetic effects in the entire extended family. Full text in Research Archive
• Demange, Perline Aline Delle (2025). Opening remarks. Social science genetics: what, why, and how. 2025. Full text in Research Archive
• NIFU (2025). Folkehelse og livsmestring i skolen. Full text in Research Archive Show summary

  NIFU Webinar on Vimeo

• Nes, Ragnhild Bang (2025). Ny forskning: Penger og økt forbruk er ikke veien til lykke. [Internet]. TV2. Full text in Research Archive
• Nes, Ragnhild Bang (2025). I tried the Nordic art of dugnadsånd for a week - I'm happier and less anxious. [Internet]. The I Paper. Full text in Research Archive
• Flatø, Martin; Torvik, Fartein Ask; Monstad, Karin & Stoltenberg, Camilla (2025). Vi har et skrikende behov for kunnskap om barn. doi: https:/www.altinget.no/artikkel/vi-har-et-skrikende-behov-for-kunnskap-om-barn. Full text in Research Archive Show summary

  Fallende skoleprestasjoner og økt fravær avdekker et skrikende behov for kunnskap for å møte vår tids utfordringer. Til det trenger vi registre fra skoler og barnehager, skriver Martin Flatø, Fartein Ask Torvik, Karin Monstad og Camilla Stoltenberg.

• Hansen, Thomas (2025). Digital bridges to social connection: A systematic review of the effect of digital interventions on loneliness and social isolation. Full text in Research Archive
• Jessen, Reidar Schei (2025). Skeive hverdagsliv i storsamfunnet. 62(6), p. 51–52. Full text in Research Archive Show summary

  https://www.psykologtidsskriftet.no/artikkel/2025as06ae-Skeive-hverdagsliv-i-storsamfunnet

• Hansen, Thomas (2025). En systematisk gjennomgang av oversiktsartikler på effekter av tiltak for å redusere ensomhet og sosial isolasjon (2017-2022). Full text in Research Archive
• Nes, Ragnhild Bang (2025). Smakebit på sommervarmen i vente: – Vi blir gladere. [Internet]. TV2. Full text in Research Archive
• Nes, Ragnhild Bang (2025). Hvordan kan man ikke bli glad av dette? [Journal]. NRK. Full text in Research Archive
• Nes, Ragnhild Bang (2025). Folkehelse og livskvalitet i Oslo. Full text in Research Archive
• Nes, Ragnhild Bang (2025). Linnéa Myhre gikk fra negativ til positiv. Grepene hylles av ekspert. [Journal]. VG. Full text in Research Archive
• Nes, Ragnhild Bang (2025). Forskere: Dette gjør deg sliten og ulykkelig. [Journal]. Nettavisen, Østlands-posten, Hamar Arbeiderblad. Full text in Research Archive
• Nes, Ragnhild Bang (2025). Går tiden for fort? Slik bremser du den. [Journal]. VG. Full text in Research Archive
• Engell, Thomas; Helland, Siri Saugestad; Vira, Emily Gabriela; Berg, Silje; Kvamme, Euryph Line Solheim & Kjøbli, John [Show all 16 contributors for this article] (2025). The implementability and proximal effects of a transdiagnostic mental health intervention for adolescents (Kort): protocol for a mixed-methods intensive longitudinal study. doi: 10.1186/s12913-025-12661-5. Full text in Research Archive Show summary

  Background This protocol describes a study designed to test the implementability and proximal effects of a transdiagnostic mental health intervention for adolescents in school health services. The study is driven by the urgent need to address the rising mental health challenges among adolescents, exacerbated by the COVID-19 pandemic. Leveraging implementation science and evidence-informed intervention elements, this co-designed intervention focuses on emotion regulation (ER) as a central target for usable prevention and support. Methods The study employs a mixed-methods approach, integrating intensive longitudinal experience sampling (daily measures for 13 weeks), a micro trial, pre-, post-, and follow-up measures, audio recordings, and qualitative interviews to triangulate data from school nurses and adolescent participants. The research questions span the domains of intervention implementability, barriers and facilitators to implementation, proximal outcomes for adolescents’ emotion regulation, the mechanisms driving the intervention’s proximal effects, and response burden in experience sampling. The study aims to recruit a minimum of 25 health nurses and 46 adolescents. Discussion The study is novel in using mixed methods from multiple theoretical paradigms to examine ER as a dynamic process and transdiagnostic target outcome for promoting mental health and preventing disorders. Through daily diary and ecological momentary assessments, the study explores the intricacies of ER in real-life settings. Coupling the experience sampling with highly detailed fidelity measurement, we will observe adolescents’ day-to-day responses to intervention elements and how they affect emotion regulation. The integrated micro-trial also addresses concerns about response burden in experience sampling to optimize data collection strategies for future studies. The findings from this study can increase our understanding of ER as a mental health process, and contribute to the development of scalable, efficient, and context-appropriate mental health interventions in school nursing. Trial registration The ISRCTN-registry: ISRCTN14932526, registration date 04/04/2023.

• Lund, Ingunn Olea; Ask, Helga; Wootton, Robyn; Havdahl, Alexandra & Izotova, Anastasia (2025). Participatory Research Meeting. Full text in Research Archive
• Izotova, Anastasia; Ayorech, Ziada; Fluit, Sam & Evje, Jacob (2025). Education of Mental Health Professionals in Norway and the Role of Intersectionality in Clinical Work - Panel discussion. Full text in Research Archive
• Jessen, Reidar Schei & Sikkeland, Hans Heen (2025). Fem råd for transsynlighet. Full text in Research Archive Show summary

  https://klassekampen.no/artikkel/2025-03-31/debatt-fem-rad-for-transsynlighet/fDwg

• Siv, Bjelland & Nygaard, Egil (2025). Livsmestring på timeplanen. [Journal]. Delta oppvekst. Full text in Research Archive
• Ystrøm, Eivind (2025). Gener har nesten alt å si for IQ, ifølge studie. – Kanskje skal vi spørre hvorfor vi belønner de med høy IQ så mye. [Internet]. forskning.no. Full text in Research Archive
• Demange, Perline Aline Delle; Eilertsen, Espen Moen & Ystrøm, Eivind (2025). Beyond trio: genetic effects in the extended family. Full text in Research Archive
• Steinsbekk, Aslak; Hjelsvold, Rune; Korpås, Guri Sivertsen; Klomstén, Anne Torhild & Wold, Heidi Libæk (2025). Lokalt utdanningssnakk (rundborddiskusjon). Full text in Research Archive
• Jessen, Reidar Schei (2025). Konverteringsterapi - hva er det og hvilke psykologiske konsekvenser har det? Foredrag på Pasientorganisasjonen for kjønnsinkongruens' frokostseminar "Ti år senere: Har vi fått rett til rett kjønn?". Full text in Research Archive
• Øksnes, Janne; Degerud, Eirik Magnus Meek; Nygaard, Egil & Kloster, Madelen (2025). Tall og fakta - Vold og trusler i skolen - del 1. [Internet]. LYpodden. Full text in Research Archive
• Øksnes, Janne; Nygaard, Egil; Kloster, Madelen & Degerud, Eirik Magnus Meek (2025). Vold og trusler i skolen – del 3; hva med elevene? [Internet]. LYpodden. Full text in Research Archive
• Gry, Wold & Havdahl, Alexandra (2025). Autisme: Ny studie gir håp. [Journal]. Dagsavisen. Full text in Research Archive
• Nes, Ragnhild Bang (2025). Helgemorgen. [TV]. NRK 1. Full text in Research Archive
• Torvik, Fartein Ask (2025). Partner choice and social inequality. Full text in Research Archive
• Do, Kathy T.; Groep, Suzanne van de; Crone, Eveline A. & Tamnes, Christian Krog (2025). A developmental neuroscience perspective on youth contributions and challenges in a changing society. Developmental Cognitive Neuroscience. ISSN 1878-9293. doi: 10.1016/j.dcn.2025.101558. Full text in Research Archive
• Czajkowski, Nikolai Olavi (2025). Kan kunstig intelligens være empatisk? Tidsskrift for Den norske legeforening (Tidsskriftet). ISSN 0029-2001. 145(2), p. 117–117. doi: 10.4045/tidsskr.25.0044. Full text in Research Archive
• Ofstad, Sverre Berg & Andersson, Björn (2026). Karakterulempen ved å velge realfag: I hvilken grad veier realfagspoengene opp for den? Universitetet i Oslo. doi: https:/www.uv.uio.no/cemo/english/about/news-events-and-publications/news/2026/bonus-points-natural-science.html. Full text in Research Archive
• Fluit, Sam (2026). Homo Politicus: Investigations on the Role of Psychosocial Development in Political Attitudes and Behavior. Universitetet i Oslo. Full text in Research Archive Show summary

  In times of political polarization, understanding the factors that shape political attitudes and behavior is crucial. Recent research and policy reports have emphasized the importance of psychosocial factors, pointing to possible links between polarization and ongoing crises in mental health and social belonging. The central aim of this doctoral thesis was to advance knowledge about how psychosocial factors influence political preference formation across the life course. To do so, I drew on large-scale longitudinal data spanning key developmental stages, from adolescence to midlife. This thesis examined three important psychosocial domains: mental health, self-esteem, and interpersonal relationships, and their role in shaping political preferences in adulthood. Together, these factors were studied in relation to more than a dozen indicators of political attitudes and voting behavior. The project comprised three studies based on two longitudinal datasets from Norway and New Zealand—both multi-party political systems characterized by coalition governments. Although this is the dominant democratic model worldwide, political attitudes in multi-party contexts remain relatively understudied. Each study employed distinct longitudinal designs, offering different advantages for examining how psychosocial factors and political preferences are interrelated. Papers 1 and 2 used Norwegian data following 2,215 participants across five waves spanning 28 years, beginning in adolescence (1992) and ending in midlife (2020). Paper 3 drew on annual dyadic data from 1,613 intimate partner couples in New Zealand, followed for 10 years (2013–2022). Paper 1 used latent class growth analysis to assess how internalizing problems (depressive symptoms and anxiety) and externalizing problems (conduct problems) from adolescence to midlife related to 12 political outcomes, including political orientation, trust, and voting behavior. Paper 2 applied latent growth curve modeling to three types of self-esteem—general, social, and close friendship—to examine to what extent their developmental trajectories are associated with polarization-related attitudes including social dominance orientation, opposition to immigration, and opposition to gender equality. Paper 3 used actor–partner interdependence random-intercept cross-lagged panel models to test whether changes in one partner’s political preferences predicted changes in the other partner’s preferences the following year. The findings provide several key insights. First, the analysis of mental health trajectories identified three classes for internalizing problems and two for externalizing problems. Individuals in the classes with high levels of either showcased lower political and social trust in midlife. Furthermore, high internalizing problems were associated with more left-leaning orientations and attitudes, while those with high externalizing problems demonstrated more right-leaning populist tendencies. Second, the self-esteem analyses showed that low self-esteem in adolescence, as well as depressed self-esteem across three decades, were associated with stronger social dominance orientation and greater opposition to immigration and gender equality. These findings were consistent across all self-esteem domains and while controlling for adolescent conservatism and other key covariates. Third, the intimate partner study demonstrated that increases in one partner’s party support predicted increases in the other partner’s support the following year. These partner effects appeared for six political parties and, with one exception, were equally strong among women and men. Taken together, the three studies lead to two overarching conclusions about psychosocial development and political preferences in adulthood. First, adolescence is a critical period: psychosocial challenges such as internalizing or externalizing problems or low self-esteem are associated with distinct political outcomes decades later, particularly when these challenges persist beyond adolescence. Second, political attitudes continue to evolve in adulthood. Intimate partners play a role in shaping these changes. In sum, this thesis demonstrates that political attitudes and behaviors are not fixed early in life but are shaped by long-term psychosocial trajectories. Drawing on decades of longitudinal data, it provides clearer insight into how mental health, self-esteem, and interpersonal relationships relate to political preferences, while also highlighting pathways that may contribute to political polarization.

• Luhmann, Maike; Potočár, Libor; Lee, Yeeun Archer; Nyqvist, Fredrica; Kleinschlömer, Pauline & Qualter, Pamela [Show all 8 contributors for this article] (2026). The Next Big Questions in Loneliness Research: A White Paper. Zenodo. doi: 10.5281/zenodo.18935284. Full text in Research Archive
• Peng, Qiyuan; Eilertsen, Espen Moen; Cheesman, Rosa Catherine Gillespie; Rietveld, Cornelius A.; Ystrom, Eivind & Havdahl, Alexandra (2025). Parental Influence on Children’s Educational Achievements: Analysing Direct and Indirect Genetic Effects through Trio-GCTA. bioRxiv. doi: https:/www.biorxiv.org/content/10.64898/2025.12.03.691991v1.article-info. Full text in Research Archive Show summary

  Educational achievement is a key predictor of later-life outcomes, including financial security, social mobility, health, and mortality. Knowing its familial determinants, such as genetic predispositions, is crucial for understanding intergenerational educational mobility and addressing educational inequality. Here, we disentangle direct and indirect genetic effects on educational achievement using trio genome-wide complex trait analysis (Trio-GCTA). Leveraging up to 23,200 genotyped parent–offspring trios from the Norwegian Mother, Father, and Child Cohort Study (MoBa), we find that direct genetic effects explain 15-21% of the variance in educational achievements, including 8th-grade national assessments in Math, Reading, and English, and 10th-grade grade point average (GPA). Notably, indirect genetic effects additionally explain 7-15% of the variance. Both mothers and fathers exert notable influences, exceeding those suggested in previous studies. Moreover, positive gene–environment correlations between parents and offspring show that the intrafamilial environment and children’s genetic predisposition are dependent and mutually reinforcing.

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