Alexandra Havdahl

• Howe, Laurence J.; Nivard, Michel G.; Morris, Tim T.; Hansen, Ailin Falkmo; Rasheed, Humaira & Cho, Yoonsu [Show all 106 contributors for this article] (2022). Within-sibship genome-wide association analyses decrease bias in estimates of direct genetic effects. Nature Genetics. ISSN 1061-4036. 54(5), p. 581–592. doi: 10.1038/s41588-022-01062-7. Full text in Research Archive
• Havdahl, Alexandra; Wootton, Robyn E; Leppert, Beate; Riglin, Lucy; Ask, Helga & Tesli, Martin Steen [Show all 16 contributors for this article] (2022). Associations between Pregnancy-Related Predisposing Factors for Offspring Neurodevelopmental Conditions and Parental Genetic Liability to Attention-Deficit/Hyperactivity Disorder, Autism, and Schizophrenia: The Norwegian Mother, Father and Child Cohort Study (MoBa). JAMA psychiatry. ISSN 2168-6238. doi: 10.1001/jamapsychiatry.2022.1728.
• Isungset, Martin Arstad; Conley, Dalton C; Zachrisson, Henrik Daae; Ystrøm, Eivind; Havdahl, Alexandra & Njølstad, Pål Rasmus [Show all 7 contributors for this article] (2022). Social and genetic associations with educational performance in a Scandinavian welfare state. Proceedings of the National Academy of Sciences of the United States of America. ISSN 0027-8424. 119(25). doi: 10.1073/pnas.2201869119.
• Magnus, Maria Christine; Havdahl, Alexandra; Wilcox, Allen J. & Goisis, Alice (2022). Parental fecundability and neurodevelopmental delays and difficulties in offspring. International Journal of Epidemiology. ISSN 0300-5771. p. 1–11. doi: 10.1093/ije/dyac094.
• Jami, Eshim S.; Hammerschlag, Anke R.; Ip, Hill F.; Allegrini, Andrea G.; Benyamin, Beben & Border, Richard [Show all 94 contributors for this article] (2022). Genome-wide association meta-analysis of childhood and adolescent internalizing symptoms. Journal of the American Academy of Child and Adolescent Psychiatry. ISSN 0890-8567. p. 1–12. doi: 10.1016/j.jaac.2021.11.035. Full text in Research Archive
• Caramaschi, Doretta; Neumann, Alexander; Cardenas, Andres; Tindula, Gwen; Alemany, Silvia & Zillich, Lea [Show all 40 contributors for this article] (2022). Meta-analysis of epigenome-wide associations between DNA methylation at birth and childhood cognitive skills. Molecular Psychiatry. ISSN 1359-4184. doi: 10.1038/s41380-022-01441-w.
• Torvik, Fartein Ask; Eilertsen, Espen Moen; Hannigan, Laurie J.; Cheesman, Rosa Catherine Gillespie; Howe, Laurence J. & Magnus, Per Minor [Show all 11 contributors for this article] (2022). Modeling assortative mating and genetic similarities between partners, siblings, and in-laws. Nature Communications. ISSN 2041-1723. 13(1), p. 1–10. doi: 10.1038/s41467-022-28774-y. Full text in Research Archive
• Dack, Kyle; Fell, Matthew; Taylor, Caroline M.; Havdahl, Alexandra & Lewis, Sarah J. (2022). Prenatal Mercury Exposure and Neurodevelopment up to the Age of 5 Years: A Systematic Review. International Journal of Environmental Research and Public Health. 19(4), p. 1–25. doi: 10.3390/ijerph19041976. Full text in Research Archive
• Watson, H; et, al.; Andreassen, Ole; Ask, Helga; et, al. & Havdahl, Alexandra [Show all 7 contributors for this article] (2021). Common Genetic Variation And Age at Onset Of Anorexia Nervosa. biological psychiatry: global open science. ISSN 2667-1743.
• Ask, Helga; Eilertsen, Espen Moen; Gjerde, Line Cecilie; Hannigan, Laurie John; Gustavson, Kristin & Havdahl, Alexandra [Show all 12 contributors for this article] (2021). Intergenerational transmission of parental neuroticism to emotional problems in 8-year-old children: Genetic and environmental influences. JCPP Advances. ISSN 2692-9384. 1(4). doi: 10.1002/jcv2.12054. Full text in Research Archive
• Haan, Elis; Sallis, Hannah M.; Zuccolo, Luisa; Labrecque, Jeremy; Ystrøm, Eivind & Reichborn-Kjennerud, Ted [Show all 9 contributors for this article] (2021). Prenatal smoking, alcohol and caffeine exposure and maternal-reported attention deficit hyperactivity disorder symptoms in childhood: triangulation of evidence using negative control and polygenic risk score analyses. Addiction. ISSN 0965-2140. 117(5), p. 1458–1471. doi: 10.1111/add.15746. Full text in Research Archive
• Lord, Catherine; Charman, Tony; Havdahl, Alexandra; Carbone, Paul; Anagnostou, Evdokia & Boyd, Brian [Show all 32 contributors for this article] (2021). The Lancet Commission on the future of care and clinical research in autism. The Lancet. ISSN 0140-6736. 399, p. 271–334. doi: 10.1016/S0140-6736%2821%2901541-5. Full text in Research Archive Show summary

  Affecting about 78 million people worldwide, autism is a condition of global importance because of its prevalence and the degree to which it can affect individuals and families. Autism awareness has grown monumentally in the past 20 years, yet most striking is that much more could be done to improve life outcomes for the highly heterogeneous group of people with autism. Such change will depend on investments in science focused on practical clinical issues, and on social and service systems that acknowledge the potential for change and growth as well as the varied, complex needs of the autistic individuals and their families whose lives could be changed with such an effort. The Lancet Commission on the future of care and clinical research in autism aims to answer the question of what can be done in the next 5 years to address the current needs of autistic individuals and families worldwide. Autism is a neurodevelopmental disorder that typically begins to manifest in early childhood and affects social communication and behaviours throughout the life span. Autism and other neurodevelopmental disorders have seen a tremendous influx of interest from the scientific community in the past 60 years. Substantial progress has been made in many areas of basic and applied science, but the limits of the knowledge and understanding of autism are also very clear. For clinical purposes, reviews and guidelines have proliferated, although the data on which many recommendations are based are typically from short-term interventions that address acquisition of specific skills that are hoped—but not yet known with confidence—to contribute to long-term gains across development. However, large gaps around key questions remain, such as what interventions and support strategies are effective for whom and when, and which interventions lead to changes beyond their proximal outcomes. Underlying these outstanding questions is a deep scarcity of information about what are the active elements or mechanisms, behavioural or neurobiological, for change. These issues are particularly important because autism affects from toddlers to elders and is almost always accompanied by other developmental, behavioural, and mental health difficulties or conditions that have major implications for lifelong outcomes.

• Ip, Hill F.; van der Laan, Camiel M.; Krapohl, Eva M. L.; Brikell, Isabell; Sánchez-Mora, Cristina & Nolte, Ilja M. [Show all 50 contributors for this article] (2021). Genetic association study of childhood aggression across raters, instruments, and age. Translational Psychiatry. ISSN 2158-3188. 11, p. 1–9. doi: 10.1038/s41398-021-01480-x. Full text in Research Archive
• Askeland, Ragna Bugge; Hannigan, Laurie J.; Ask, Helga; Ayorech, Ziada; Tesli, Martin Steen & Corfield, Elizabeth [Show all 12 contributors for this article] (2021). Early manifestations of genetic risk for neurodevelopmental disorders. Journal of Child Psychology and Psychiatry. ISSN 0021-9630. p. 1–10. doi: 10.1111/jcpp.13528. Full text in Research Archive
• Haan, E; Sallis, H; Ystrøm, Eivind; Njølstad, Pål Rasmus; Andreassen, Ole & Reichborn-Kjennerud, Ted [Show all 9 contributors for this article] (2021). Maternal and offspring genetic risk score analyses of fetal alcohol exposure and attention-deficit hyperactivity disorder risk in offspring. Alcoholism: Clinical and Experimental Research. ISSN 0145-6008. 45(10), p. 2090–2102. doi: 10.1111/acer.14692. Full text in Research Archive
• Friel, Catherine; Leyland, Alastair H.; Anderson, Jana J.; Havdahl, Alexandra; Borge, Tiril Cecilie & Shimonovich, Michal [Show all 7 contributors for this article] (2021). Prenatal vitamins and the risk of offspring autism spectrum disorder: Systematic review and meta-analysis. Nutrients. ISSN 2072-6643. 13. doi: 10.3390/nu13082558. Full text in Research Archive
• Peyre, Hugo; Schoeler, Tabea; Liu, Chaoyu; Williams, Camille Michèle; Hoertel, Nicolas & Havdahl, Alexandra [Show all 7 contributors for this article] (2021). Combining multivariate genomic approaches to elucidate the comorbidity between autism spectrum disorder and attention deficit hyperactivity disorder. Journal of Child Psychology and Psychiatry. ISSN 0021-9630. 62(11), p. 1285–1296. doi: 10.1111/jcpp.13479.
• Dack, Kyle; Fell, Matthew; Taylor, Caroline M.; Havdahl, Alexandra Karoline Saasen & Lewis, Sarah J. (2021). Mercury and prenatal growth: A systematic review. International Journal of Environmental Research and Public Health (IJERPH). ISSN 1661-7827. 18:7140(13), p. 1–19. doi: 10.3390/ijerph18137140. Full text in Research Archive
• Magnus, Maria Christine; Havdahl, Alexandra; Morken, Nils-Halvdan; Wensaas, Knut-Arne; Wilcox, Allen J. & Håberg, Siri Eldevik (2021). Risk of miscarriage in women with psychiatric disorders. British Journal of Psychiatry. ISSN 0007-1250. 219(3), p. 501–506. doi: 10.1192/bjp.2020.259. Full text in Research Archive Show summary

  Background Some psychiatric disorders have been associated with increased risk of miscarriage. However, there is a lack of studies considering a broader spectrum of psychiatric disorders to clarify the role of common as opposed to independent mechanisms. Aims To examine the risk of miscarriage among women diagnosed with psychiatric conditions. Method We studied registered pregnancies in Norway between 2010 and 2016 (n = 593 009). The birth registry captures pregnancies ending in gestational week 12 or later, and the patient and general practitioner databases were used to identify miscarriages and induced abortions before 12 gestational weeks. Odds ratios of miscarriage according to 12 psychiatric diagnoses were calculated by logistic regression. Miscarriage risk was increased among women with bipolar disorders (adjusted odds ratio 1.35, 95% CI 1.26–1.44), personality disorders (adjusted odds ratio 1.32, 95% CI 1.12–1.55), attention-deficit hyperactivity disorder (adjusted odds ratio 1.27, 95% CI 1.21–1.33), conduct disorders (1.21, 95% CI 1.01, 1.46), anxiety disorders (adjusted odds ratio 1.25, 95% CI 1.23–1.28), depressive disorders (adjusted odds ratio 1.25, 95% CI 1.23–1.27), somatoform disorders (adjusted odds ratio 1.18, 95% CI 1.07–1.31) and eating disorders (adjusted odds ratio 1.14, 95% CI 1.08–1.22). The miscarriage risk was further increased among women with more than one psychiatric diagnosis. Our findings were robust to adjustment for other psychiatric diagnoses, chronic somatic disorders and substance use disorders. After mutual adjustment for co-occurring psychiatric disorders, we also observed a modest increased risk among women with schizophrenia spectrum disorders (adjusted odds ratio 1.22, 95% CI 1.03–1.44). Conclusions A wide range of psychiatric disorders were associated with increased risk of miscarriage. The heightened risk of miscarriage among women diagnosed with psychiatric disorders highlights the need for awareness and surveillance of this risk group in antenatal care.

• Havdahl, Alexandra; Niarchou, Maria; Starnawska, A; Uddin, M; van der Merwe, Celia & Warrier, Varun (2021). Genetic contributions to autism spectrum disorder. Psychological Medicine. ISSN 0033-2917. 51(13), p. 2260–2273. doi: 10.1017/S0033291721000192. Full text in Research Archive Show summary

  Autism spectrum disorder (autism) is a heterogeneous group of neurodevelopmental conditions characterized by early childhood-onset impairments in communication and social interaction alongside restricted and repetitive behaviors and interests. This review summarizes recent developments in human genetics research in autism, complemented by epigenetic and transcriptomic findings. The clinical heterogeneity of autism is mirrored by a complex genetic architecture involving several types of common and rare variants, ranging from point mutations to large copy number variants, and either inherited or spontaneous (de novo). More than 100 risk genes have been implicated by rare, often de novo, potentially damaging mutations in highly constrained genes. These account for substantial individual risk but a small proportion of the population risk. In contrast, most of the genetic risk is attributable to common inherited variants acting en masse, each individually with small effects. Studies have identified a handful of robustly associated common variants. Different risk genes converge on the same mechanisms, such as gene regulation and synaptic connectivity. These mechanisms are also implicated by genes that are epigenetically and transcriptionally dysregulated in autism. Major challenges to understanding the biological mechanisms include substantial phenotypic heterogeneity, large locus heterogeneity, variable penetrance, and widespread pleiotropy. Considerable increases in sample sizes are needed to better understand the hundreds or thousands of common and rare genetic variants involved. Future research should integrate common and rare variant research, multi-omics data including genomics, epigenomics, and transcriptomics, and refined phenotype assessment with multidimensional and longitudinal measures.

• Eilertsen, Espen Moen; Jami, Eshim Shahid; McAdams, Tom A.; Hannigan, Laurie J.; Havdahl, Alexandra & Magnus, Per [Show all 8 contributors for this article] (2021). Direct and Indirect Effects of Maternal, Paternal, and Offspring Genotypes: Trio-GCTA. Behavior Genetics. ISSN 0001-8244. 51, p. 154–161. doi: 10.1007/s10519-020-10036-6. Full text in Research Archive
• Hannigan, Laurie John; Askeland, Ragna Bugge; Ask, Helga; Tesli, Martin; Corfield, Elizabeth & Ayorech, Ziada [Show all 15 contributors for this article] (2021). Genetic Liability for Schizophrenia and Childhood Psychopathology in the General Population. Schizophrenia Bulletin. ISSN 0586-7614. 47(4), p. 1179–1189. doi: 10.1093/schbul/sbaa193. Full text in Research Archive
• Sallis, Hannah M.; Croft, Jazz; Havdahl, Alexandra; Jones, Hannah J.; Dunn, Erin C. & Smith, George Davey [Show all 8 contributors for this article] (2020). Genetic liability to schizophrenia is associated with exposure to traumatic events in childhood. Psychological Medicine. ISSN 0033-2917. doi: 10.1017/S0033291720000537.
• Havdahl, Alexandra; Farmer, Cristan; Schjølberg, Synnve; Øyen, Anne-Siri; Suren, Pål & Reichborn-Kjennerud, Ted [Show all 15 contributors for this article] (2020). Age of walking and intellectual ability in autism spectrum disorder and other neurodevelopmental disorders: a population‐based study. Journal of Child Psychology and Psychiatry. ISSN 0021-9630. p. 1–9. doi: 10.1111/jcpp.13369. Full text in Research Archive
• Kiselev, Yury; Handal, Marte; Hjellvik, Vidar; Reichborn-Kjennerud, Ted; Stoltenberg, Camilla & Suren, Pål [Show all 8 contributors for this article] (2020). Nationwide study of neuropsychiatric comorbidity and medicines use in children with autism spectrum disorder in Norway. Frontiers in Psychiatry. ISSN 1664-0640. 11, p. 1–8. doi: 10.3389/fpsyt.2020.596032.
• Cheesman, Rosa; Eilertsen, Espen Moen; Ahmadzadeh, Yasmin I.; Gjerde, Line C.; Hannigan, Laurie John & Havdahl, Alexandra [Show all 13 contributors for this article] (2020). How important are parents in the development of child anxiety and depression? A genomic analysis of parent-offspring trios in the Norwegian Mother Father and Child Cohort Study (MoBa). BMC Medicine. ISSN 1741-7015. 18. doi: 10.1186/s12916-020-01760-1. Full text in Research Archive
• Akingbuwa, Wonuola A.; Hammerschlag, Anke R.; Jami, Eshim S.; Allegrini, Andrea G.; Karhunen, Ville & Sallis, Hannah [Show all 35 contributors for this article] (2020). Genetic Associations Between Childhood Psychopathology and Adult Depression and Associated Traits in 42 998 Individuals: A Meta-analysis. JAMA psychiatry. ISSN 2168-6238. 77(7), p. 715–728. doi: 10.1001/jamapsychiatry.2020.0527. Full text in Research Archive
• Brumpton, Ben Michael; Sanderson, Eleanor; Heilbron, Karl; Hartwig, FP; Harrison, S & Vie, Gunnhild Åberge [Show all 35 contributors for this article] (2020). Avoiding dynastic, assortative mating, and population stratification biases in Mendelian randomization through within-family analyses. Nature Communications. ISSN 2041-1723. 11. doi: 10.1038/s41467-020-17117-4. Full text in Research Archive
• Torvik, Fartein Ask; Eilertsen, Espen Moen; McAdams, Tom A.; Gustavson, Kristin; Zachrisson, Henrik Daae & Brandlistuen, Ragnhild Eek [Show all 11 contributors for this article] (2020). Mechanisms linking parental educational attainment with child ADHD, depression, and academic problems: a study of extended families in The Norwegian Mother, Father and Child Cohort Study. Journal of Child Psychology and Psychiatry. ISSN 0021-9630. 61(9), p. 1009–1018. doi: 10.1111/jcpp.13197. Full text in Research Archive
• Davies, Neil M.; Howe, Laurence; Brumpton, Ben Michael; Havdahl, Alexandra; Evans, David M. & Smith, George Davey (2019). Within family Mendelian randomization studies. Human Molecular Genetics. ISSN 0964-6906. 28(2), p. R170–R179. doi: 10.1093/hmg/ddz204. Full text in Research Archive
• Suren, Pål; Havdahl, Alexandra; Øyen, Anne-Siri; Schjølberg, Synnve; Reichborn-Kjennerud, Ted & Magnus, Per [Show all 8 contributors for this article] (2019). Diagnosing autism spectrum disorder among children in Norway . Tidsskrift for Den norske legeforening. ISSN 0029-2001. 139(14), p. 1372–1379. doi: 10.4045/tidsskr.18.0960. Full text in Research Archive Show summary

  BACKGROUND:The percentage share of children who are diagnosed with autism spectrum disorder has increased considerably since the 1990s in Norway as well as in other countries. It has previously been demonstrated that there is considerable variation between counties with respect to diagnostic practice. MATERIAL AND METHOD:We calculated the percentage of children with autism spectrum disorder by using patient data obtained from the Norwegian Patient Registry and population data obtained from the National Registry. The calculations were made for the country as a whole as well as by county. The diagnostic assessments and documentation were mapped by linking the Norwegian Patient Registry with the Norwegian Mother, Father and Child Cohort study. We also reviewed patient records obtained from the specialist health service and considered whether diagnostic practice satisfied the research criteria for autism spectrum disorder. RESULTS:By the age of eight, 1.1 % of boys and 0.3 % of girls had been diagnosed with autism spectrum disorder. The overall percentages varied from 0.3 to 1.0 between counties. From 2008 to 2016, these percentages increased in all age groups. Our review of patient records included 503 children. In 95 % of cases the patient records provided a high standard of documentation that the diagnostic research criteria had been satisfied. The assessments were largely conducted in accordance with the guidelines drawn up by the various health trusts. INTERPRETATION:Autism diagnoses are generally well documented within the Norwegian specialist health service and meet the diagnostic criteria. In the counties that demonstrate a low prevalence of autism, it appears the health service fails to recognise autism in many children, particularly girls, or the diagnosis is determined late.

• Leppert, Beate; Havdahl, Alexandra; Riglin, Lucy; Jones, Hannah J.; Zheng, Jie & Davey Smith, George [Show all 10 contributors for this article] (2019). Association of maternal neurodevelopmental risk alleles with early-life exposures. JAMA psychiatry. ISSN 2168-6238. 76(8), p. 834–842. doi: 10.1001/jamapsychiatry.2019.0774. Full text in Research Archive
• Suren, Pål; Havdahl, Alexandra; Bresnahan, Michaeline; Hirtz, Deborah; Hornig, Mady & Lord, Catherine [Show all 13 contributors for this article] (2019). Sensitivity and specificity of early screening for autism. BJPsych Open. ISSN 2056-4724. 5(3). doi: 10.1192/bjo.2019.34. Full text in Research Archive
• Havdahl, Alexandra; Ruth, Mitchell; Lavinia, Paternoster & Davey Smith, George (2019). Investigating causality in the association between vitamin D status and self-reported tiredness. Scientific Reports. ISSN 2045-2322. 9. doi: 10.1038/s41598-019-39359-z. Full text in Research Archive
• Caramaschi, Doretta; Taylor, Amy; Richmond, Rebecca C.; Havdahl, Alexandra; Golding, Jean & Relton, Caroline [Show all 9 contributors for this article] (2018). Maternal smoking during pregnancy and autism: using causal inference methods in a birth cohort study. Translational Psychiatry. ISSN 2158-3188. 8(262). doi: 10.1038/s41398-018-0313-5.
• Ask, Helga; Gustavson, Kristin; Ystrøm, Eivind; Havdahl, Karoline Alexandra; Tesli, Martin Steen & Askeland, Ragna Bugge [Show all 7 contributors for this article] (2018). Association of Gestational Age at Birth With Symptoms of Attention-Deficit/Hyperactivity Disorder in Children. JAMA pediatrics. ISSN 2168-6203. 172(8), p. 749–756. doi: 10.1001/jamapediatrics.2018.1315. Full text in Research Archive
• Øien, Roald A; Schjølberg, Synnve; Volkmar, Fred R.; Shic, Frederick; Cicchetti, Domenic V. & Nordahl-Hansen, Anders Johan [Show all 14 contributors for this article] (2018). Clinical Features of Children With Autism Who Passed 18-Month Screening. Pediatrics. ISSN 0031-4005. 141(6). doi: 10.1542/peds.2017-3596. Full text in Research Archive
• Havdahl, Karoline Alexandra; Bishop, Somer L.; Surén, Pål; Øyen, Anne-Siri; Lord, Catherine & Pickles, Andrew [Show all 17 contributors for this article] (2017). The influence of parental concern on the utility of autism diagnostic instruments. Autism Research. ISSN 1939-3792. 10(10), p. 1672–1686. doi: 10.1002/aur.1817.
• Bishop, Somer L.; Farmer, Cristan; Hus Bal, Vanessa; Robinson, Elise; Willsey, AJ & Werling, DM [Show all 9 contributors for this article] (2017). Identification of Developmental and Behavioral Markers Associated With Genetic Abnormalities in Autism Spectrum Disorder. American Journal of Psychiatry. ISSN 0002-953X. 174(6), p. 576–585. doi: 10.1176/appi.ajp.2017.16101115.

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• Askelund, Adrian Dahl; Hegemann, Laura; Corfield, Elizabeth Claire; Ask, Helga; Ystrøm, Eivind & Havdahl, Alexandra [Show all 7 contributors for this article] (2022). The genomics of psychiatric symptom differentiation in early life. Show summary

  Background: An emerging body of evidence suggests that genetic risk for psychiatric conditions is diffuse, probabilistic in nature, and overlaps substantially across different domains. However, psychiatric conditions are diagnosed and treated as specific disorders based on differentiated symptom clusters. In the context of generalised genetic risk, it remains to be determined how distinct psychiatric conditions emerge. The prospects of using genomic data to predict individual-level risk for psychiatric conditions are at present unclear. For prediction to be useful, it needs to be both sensitive (identifying who is at risk) and specific (at risk for what). While increasing sample sizes for genetic discovery may boost sensitivity, the generalised nature of genetic risk implies that identifying predictors of differentiation of psychiatric symptoms may be needed to increase specificity. The Norwegian Mother, Father, and Child Cohort Study (MoBa) is a large population-based pregnancy cohort with genotype and phenotype data, ideally suited to address these questions. Methods: We used the Child Behavior Checklist to assess behavioural and emotional difficulties at ages 1.5, 3, and 5. Symptom¬ differentiation was operationalised as the relative level of these domains over time (behavioural difficulties – emotional difficulties = differentiation). This means that individuals with high scores have relatively more behavioural than emotional difficulties, and the inverse for low scores. These scores can be compared to overall difficulties (behavioural + emotional = total). Following a preregistered analysis plan, we estimated latent growth trajectories of differentiation across early childhood, as well as mediation effects of differentiation on symptoms of psychiatric conditions at age 8. We tested associations between 10 polygenic scores (PGS) for core neurodevelopmental and psychiatric conditions and the extent (intercept) and rate (slope) of the differentiation process. The analytic sample comprised 57,387 genotyped children (including 12,347 pairs of full siblings) from MoBa. We used multilevel structural equation models to account for unmeasured familial confounding, and corrected for multiple comparisons using FDR. Results: ADHD PGS predicted the extent and rate of differentiation toward behavioural difficulties in early childhood (βintercept = 0.10 [0.09, 0.11]; βslope = 0.02 [0.02, 0.03]), and the extent of differentiation at age 5 in turn mediated 33-37% of the PGS associations with ADHD symptoms at age 8. The ADHD PGS association was smaller for total difficulties (βintercept = 0.05 [0.04, 0.06]; βslope = 0.01 [0.01, 0.02]). Schizophrenia PGS predicted differentiation toward emotional difficulties at age 5 (βintercept = -0.03 [-0.04, -0.02]; βslope = -0.01 [-0.02, -0.01]), and bipolar disorder PGS predicted differentiation toward behavioural difficulties (βintercept = 0.02 [0.01, 0.03]; βslope = 0.01 [0.01, 0.02]) – though in both cases effect sizes were substantially smaller. Discussion: We identify genomic predictors of symptom differentiation in early life. Results support a direct effect of ADHD PGS on differentiation toward behavioural difficulties, independent of individuals’ total burden of symptoms. PGS for schizophrenia and bipolar disorder differentially associates with the development of emotional and behavioural difficulties in early childhood. This research may help refine risk predictions in child psychiatry, an important step to enable early prevention.

• Askeland, Ragna Bugge; Hannigan, Laurie John; O'Connell, Kevin Sean; Corfield, Elizabeth Claire; Frei, Oleksandr & Thapar, Anita [Show all 11 contributors for this article] (2022). Developmental manifestations of polygenic risk for bipolar disorder from infancy to middle childhood.
• Hegemann, Laura; Askeland, Ragna Bugge; Elizabeth, Corfield C.; Askelund, Adrian Dahl; Hannigan, Laurie John & Havdahl, Alexandra (2022). Exploring shared genetic liability across early neurodevelopmental delays and atypicalities in the general population.
• Wootton, Robyn E; Sallis, Hannah M.; martin, joanna; Dennison, Charlotte A.; Corfield, Elizabeth & Andreassen, Ole A [Show all 9 contributors for this article] (2022). Direct and indirect genetic effects of parental mental health on childhood emotional problems in the Norwegian Mother, Father and Child cohort study (MoBa).
• Wootton, Robyn E; Chong, Amanda; Mahmoud, Osama; Munafò, Marcus R.; Tilling, Kate & Havdahl, Alexandra (2022). Exploring the Role of Smoking in Recovery from Major Depression: A Mendelian Randomisation Study.
• Pettersen, Johanne Hagen; Hannigan, Laurie John; Eilertsen, Espen Moen; Gustavson, Kristin; Lund, Ingunn Olea & Jensen, Pia [Show all 10 contributors for this article] (2022). Indirect genetic influences on mental distress in mother-father-offspring trios during the covid-19 lockdown.
• Eilertsen, Espen Moen; Gillespie Cheesman, Rosa Catherine; Ayorech, Ziada; Røysamb, Espen; Pingault, Jean-Baptiste & Njølstad, Pål Rasmus [Show all 11 contributors for this article] (2022). On the importance of parenting in externalizing disorders: an evaluation of indirect genetic effects in families. Journal of Child Psychology and Psychiatry. ISSN 0021-9630. 63(10), p. 1186–1195. doi: 10.1111/jcpp.13654.
• Hannigan, Laurie John & Havdahl, Alexandra (2022). Editorial: Developmental Psychiatric Genetic Epidemiology: Where Are We, and What Challenges Do We Face Going Forward? Journal of the American Academy of Child and Adolescent Psychiatry. ISSN 0890-8567. 61(2), p. 125–127. doi: 10.1016/j.jaac.2021.05.014.
• Kleppestø, Thomas Haarklau; Eilertsen, Espen Moen; van Bergen, Elsje; Zeitsch, Brendan; Sunde, Hans Fredrik & Nordmo, Magnus [Show all 10 contributors for this article] (2021). Intergenerational Transmission of ADHD: More Evidence for Heritability than Fast Life History. Behavior Genetics. ISSN 0001-8244. 51(6), p. 717–717.
• Kleppestø, Thomas Haarklau; Eilertsen, Espen Moen; van Bergen, Elsje; Zeitsch, Brendan; Sunde, Hans Fredrik & Nordmo, Magnus [Show all 10 contributors for this article] (2021). Intergenerational Transmission of ADHD: More Evidence for Heritability than Fast Life History.
• Barkhuizen, Wikus; Pingault, Jean-Baptiste; Wang, Biyao; Hannigan, Laurie John; Eilertsen, Espen Moen & Andreassen, Ole [Show all 14 contributors for this article] (2021). Direct and indirect genetic influences involved in the intergenerational transmission of risk for ADHD in the Norwegian Mother, Father and Child Cohort. Behavior Genetics. ISSN 0001-8244. 51(6), p. 692–691.
• Ayorech, Ziada; Gillespie Cheesman, Rosa Catherine; Eilertsen, Espen Moen; Torvik, Fartein Ask; Andreassen, Ole & Havdahl, Alexandra [Show all 7 contributors for this article] (2021). Investigating Heterogeneity in Depression Using Multiple Polygenic Scores. European Neuropsychopharmacology. ISSN 0924-977X. 51, p. E161–E161.
• Ayorech, Ziada; Gillespie Cheesman, Rosa Catherine; Eilertsen, Espen Moen; Havdahl, Alexandra & Ystrøm, Eivind (2021). Polygenic P: Characterising the role of general liability to psychopathology in maternal depression . Behavior Genetics. ISSN 0001-8244. 51(5), p. 690–690.
• Hannigan, Laurie John; Corfield, Elizabeth; Biele, Guido; Tilling, Kate; McAdams, Tom A. & Badini, Isabella [Show all 19 contributors for this article] (2021). The genomic basis of participation in the Norwegian Mother, Father and Child Cohort Study.
• Hannigan, Laurie John; Hegemann, Laura; Wootton, Robyn; Askelund, Adrian Dahl & Havdahl, Alexandra (2021). A framework to improve polygenic questions and strengthen inferences in psychiatric genetic epidemiology .
• Wootton, Robyn; Dack, Kyle; Borges, Carolina; Pagoni, Panagiota; Riglin, Lucy & Andreassen, Ole [Show all 12 contributors for this article] (2021). Nutritional biomarkers in pregnancy and neurodevelopmental outcomes in offspring: A Mendelian Randomization study in the Norwegian Mother, Father and Child Cohort Study (MoBa).
• Ayorech, Ziada; Gillespie Cheesman, Rosa Catherine; Eilertsen, Espen Moen; Torvik, Fartein Ask; Andreassen, Ole & Havdahl, Alexandra [Show all 7 contributors for this article] (2021). Investigating Heterogeneity in Depression Using Multiple Polygenic Scores.
• Barkhuizen, Wikus; Pingault, Jean-Baptiste; Wang, Biyao; Hannigan, Laurie John; Eilertsen, Espen Moen & Andreassen, Ole [Show all 14 contributors for this article] (2021). Direct and indirect genetic influences involved in the intergenerational transmission of risk for ADHD in the Norwegian Mother, Father and Child Cohort.
• Ayorech, Ziada; Davies, Neil; Wootton, Robyn; Watson, Hunna J; Hannigan, Laurie John & Askeland, Ragna Bugge [Show all 17 contributors for this article] (2021). Differential causal risk patterns in childhood eating behaviours compared to adulthood anorexia nervosa. A Mendelian randomization study.
• Ayorech, Ziada; Gillespie Cheesman, Rosa Catherine; Eilertsen, Espen Moen; Havdahl, Alexandra & Ystrøm, Eivind (2021). Polygenic P: Characterising the role of general liability to psychopathology in maternal depression .
• Hughes, Amanda; Morris, Tim; Ayorech, Ziada; Tesli, Martin Steen; Ask, Helga & Askeland, Ragna Bugge [Show all 16 contributors for this article] (2021). The causal effect of BMI on neurodevelopment: a within family Mendelian randomization study using MoBa. International Journal of Epidemiology. ISSN 0300-5771. 50(Suppl 1). doi: 10.1093/ije/dyab168.296. Full text in Research Archive
• Havdahl, Alexandra (2021). Using genetic data to understand the causal influences of environmental factors on child development – Mendelian randomization studies in MoBa.
• Havdahl, Alexandra (2021). Separating direct and indirect genetic effects using trio designs in the Norwegian Mother, Father and Child Cohort Study (MoBa).
• Havdahl, Alexandra (2021). Prenatal nutrition and risk of offspring ADHD: A mendelian randomization study in the MoBa cohort.
• Havdahl, Alexandra Karoline Saasen; Mitchell, Ruth; Paternoster, Lavinia & Smith, George Davey (2021). Author Correction: Investigating causality in the association between vitamin D status and self-reported tiredness. Scientific Reports. ISSN 2045-2322. 11. doi: 10.1038/s41598-021-89274-5.
• Hannigan, Laurie John & Havdahl, Alexandra (2021). Meeting the challenge of multidimensionality in neurodevelopmental disorders – reflections on Johnson et al. (2021). Journal of Child Psychology and Psychiatry. ISSN 0021-9630. doi: 10.1111/jcpp.13416. Full text in Research Archive
• Havdahl, Alexandra (2020). PaGE and PsychGen: The Psychiatric Genetic Epidemiology group.
• Havdahl, Alexandra (2020). Update on psychiatric genetics research in the Norwegian Mother, Father and Child Cohort Study.
• Havdahl, Alexandra (2020). Autism and autistic traits in the Norwegian Mother, Father and Child Cohort Study (MoBa).
• Lennox, Ziada Ayorech; Davies, Neil; Hannigan, Laurie John; Askeland, Ragna Bugge; Tesli, Martin Steen & Andreassen, Ole Andreas [Show all 14 contributors for this article] (2020). Which Metabo-Psychiatric Factors Affect the Risk of Anorexia Nervosa? A Mendelian Randomization Study.
• Havdahl, Alexandra; Niarchou, M; Starnawska, A & van der Merwe, Celia (2020). Genetic contributions to autism spectrum disorder.
• Torvik, Fartein Ask; Eilertsen, Espen Moen; Hannigan, Laurie John; Havdahl, Alexandra & Ystrøm, Eivind (2020). Assortative mating and the usefulness of polygenic scores in extended pedigrees.
• Askeland, Ragna Bugge; Hannigan, Laurie John; Ask, Helga; Lennox, Ziada Ayorech; Tesli, Martin Steen & Corfield, Elizabeth [Show all 9 contributors for this article] (2020). Genetic risk factors for neurodevelopmental disorders.
• Gillespie Cheesman, Rosa Catherine; Eilertsen, Espen Moen; Ahmadzadeh, Yasmin; Gjerde, Line C.; Hannigan, Laurie & Havdahl, Alexandra [Show all 9 contributors for this article] (2019). Separating child and parent influences on child emotional problems using genomic family data. Behavior Genetics. ISSN 0001-8244. 49(6), p. 523–524. doi: 10.1007/s10519-019-09973-8.
• Ask, Helga; Eilertsen, Espen Moen; Gjerde, Line C.; Gustavson, Kristin; Hannigan, Laurie John & Havdahl, Alexandra [Show all 11 contributors for this article] (2019). Intergenerational transmission of parental neuroticism to offspring neuroticism, depression, and anxiety . Behavior Genetics. ISSN 0001-8244. 49(6), p. 548–548. doi: 10.1007/s10519-019-09973-8.
• Skurtveit, Svetlana; Kiselev, Yury; Handal, Marte; Stoltenberg, Camilla; Reichborn-Kjennerud, Ted & Suren, Pål [Show all 8 contributors for this article] (2019). Co-Occurring Neuropsychiatric Diagnoses and Use of Psychotropic Drugs in Children with Autism Spectrum Disorder. Pharmacoepidemiology and Drug Safety. ISSN 1053-8569. doi: 10.10002/pds.4864.
• Gillespie Cheesman, Rosa Catherine; Eilertsen, Espen Moen; Ahmadzadeh, Yasmin; Gjerde, Line C.; Hannigan, Laurie & Havdahl, Alexandra [Show all 9 contributors for this article] (2019). Separating child and parent influences on child emotional problems using genomic family data.
• Gillespie Cheesman, Rosa Catherine; Eilertsen, Espen Moen; Ahmadzadeh, Yasmin; Gjerde, Line C.; Hannigan, Laurie & Havdahl, Alexandra [Show all 9 contributors for this article] (2019). Separating child and parent influences on child depression and anxiety using genomic family data. European Neuropsychopharmacology. ISSN 0924-977X. 29, p. S119–S119. doi: 10.1016/j.euroneuro.2019.08.012.
• Gillespie Cheesman, Rosa Catherine; Eilertsen, Espen Moen; Ahmadzadeh, Yasmin; Gjerde, Line C.; Hannigan, Laurie & Havdahl, Alexandra [Show all 9 contributors for this article] (2019). Separating child and parent influences on child depression and anxiety using genomic family data.
• Havdahl, Alexandra (2019). Using population-based cohort studies and nationwide registries to study autism and other neurodevelopmental disorders.
• Havdahl, Alexandra (2019). Autism in Norway.
• Tesli, Martin Steen; Corfield, Elizabeth; Zayats, Tetyana; Ask, Helga; Askeland, Ragna Bugge & Hannigan, Laurie [Show all 10 contributors for this article] (2019). Investigation of shared genetic risk between cardiometabolic morbidity and ADHD in a Norwegian family cohort using polygenic transmission disequilibrium test.
• Hannigan, Laurie; Askeland, Ragna Bugge; Ask, Helga; Tesli, Martin Steen; Corfield, Elizabeth & Mcadams, Tom [Show all 10 contributors for this article] (2019). Perinatal maternal stress and early-life behavioural and emotional problems: examining the role of genetically-influenced environmental sensitivity in mothers and offspring.
• Ask, Helga; Hannigan, Laurie; Davies, Neil; Gustavson, Kristin; Biele, Guido & Richardson, Thomas [Show all 15 contributors for this article] (2019). Exploring the Associations Between Health-Related Polygenic Scores and Participation in the Norwegian Mother and Child Pregnancy Cohort (MoBa).
• Ask, Helga; Eilertsen, Espen Moen; Gjerde, Line C.; Gustavson, Kristin; Hannigan, Laurie John & Havdahl, Alexandra [Show all 11 contributors for this article] (2019). Intergenerational transmission of parental neuroticism to offspring neuroticism, depression, and anxiety .
• Askeland, Ragna Bugge; Hannigan, Laurie John; Ask, Helga; Tesli, Martin Steen; Corfield, Elizabeth & Andreassen, Ole Andreas [Show all 9 contributors for this article] (2019). Early manifestations of genetic risk for neurodevelopmental disorders.
• Askeland, Ragna Bugge; Reichborn-Kjennerud, Ted; Hannigan, Laurie John; Ask, Helga; Tesli, Martin Steen & Corfield, Elizabeth [Show all 7 contributors for this article] (2019). Early manifestation of genetic risk for attention deficit/hyperactivity disorder in Norwegian children.
• Havdahl, Alexandra; Laurie, Hannigan; Askeland, Ragna Bugge; Ask, Helga; Tesli, Martin Steen & Corfield, Elizabeth [Show all 10 contributors for this article] (2019). Polygenic Risk for ADHD and Exposures During Pregnancy in the Norwegian Mother and Child Cohort Study (MoBa).
• Havdahl, Alexandra & Bishop, Somer L. (2019). Heterogeneity in prevalence of co-occurring psychiatric conditions in autism. The Lancet Psychiatry. ISSN 2215-0374. doi: 10.1016/S2215-0366%2819%2930326-8.
• Havdahl, Alexandra (2018). Challenges in assessment of autism spectrum disorder.
• Havdahl, Alexandra (2018). Gene-Environment Interplay and Mental Health Problems.
• Havdahl, Alexandra (2018). Undersøke utvikling av psykiske helseproblemer ved bruk av molekylærgenetiske metoder .
• Havdahl, Alexandra (2018). Understanding the development of mental health problems utilizing large scale health data and novel molecular genetic models.
• Havdahl, Alexandra; Bishop, Somer L.; Farmer, Cristan; Schjølberg, Synnve; Bresnahan, Michaeline & Hirtz, Deborah [Show all 17 contributors for this article] (2018). Loss of Social-Communication Skills and Outcomes during Childhood in a Large General Population Cohort.
• Havdahl, Karoline Alexandra & Leppert, Beate (2018). Maternal health behaviours in pregnancy and neurodevelopmental disorders: Evidence of genetic confounding.
• Hus Bal, Vanessa; Havdahl, Karoline Alexandra; Bishop, Somer L.; Thurm, Audrey & Farmer, Cristan (2017). The Meaning of SRS-2 Scores is Relative: The Importance of Measurement Invariance in Outcome Measure Selection.
• Havdahl, Karoline Alexandra (2017). Best Dissertation Award Talk.
• Havdahl, Karoline Alexandra; Bal, Vanessa Hus; Huerta, Marisela; Pickles, Andrew; Øyen, Anne-Siri & Stoltenberg, Camilla [Show all 8 contributors for this article] (2017). Dr. Havdahl et al. reply. Journal of the American Academy of Child and Adolescent Psychiatry. ISSN 0890-8567. 56(7), p. 619–620. doi: 10.1016/j.jaac.2017.05.010.
• Havdahl, Karoline Alexandra; Hus Bal, Vanessa; Lord, Catherine; Pickles, Andrew & Bishop, Somer L (2017). In Reply. Journal of the American Academy of Child and Adolescent Psychiatry. ISSN 0890-8567. 56(4), p. 355–357. doi: 10.1016/j.jaac.2017.01.018.
• Askeland, Ragna Bugge; Hannigan, Laurie John; Ask, Helga; Ayorech, Ziada; Tesli, Martin Steen & Corfield, Elizabeth [Show all 12 contributors for this article] (2020). Early manifestations of genetic risk for neurodevelopmental disorders. PsyArXiv (Preprint artikkel).
• Hannigan, Laurie John; Askeland, Ragna Bugge; Ask, Helga; Tesli, Martin Steen; Corfield, Elizabeth & Ayorech, Ziada [Show all 14 contributors for this article] (2020). Developmental milestones in early childhood and genetic liability to neurodevelopmental disorders. PsyArXiv (Preprint artikkel).

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