Anders Martin Fjell

• Kransberg, Jonas Moe; Bråthen, Anne Cecilie Sjøli; Falch, Emilie Sogn; Øverbye, Knut Eiliv Ødegård; Garrido, Pablo F. & Fjell, Anders Martin [Show all 10 contributors for this article] (2026). Failure to detect entorhinal grid-like signals in a passive navigation human fMRI study. Imaging Neuroscience. 4. doi: 10.1162/imag.a.1196. Full text in Research Archive Show summary

  Abstract Grid cells in the human entorhinal cortex (EC) play a critical role in spatial navigation and memory. The EC is also one of the first regions affected by ageing and Alzheimer’s disease. This pre-registered functional magnetic resonance imaging (fMRI) study aimed to detect grid-cell-like signals (GLS) in a passive virtual navigation task. Contrary to our hypotheses and previous findings, we did not observe significant GLS at a population level, even in younger participants. Further exploratory analyses investigated the impact of task-engagement, as inferred from object-location memory performance, and showed no relationship with GLS magnitude. We also examined potential influences of a confounding one-fold directional signal and various data-processing choices but observed no consistent patterns. Our findings, consistent with recent null results from similar studies, suggest that passive navigation paradigms may be insufficient for reliably eliciting grid-like signals in human fMRI.

• Walhovd, Kristine B; Bråthen, Anne Cecilie Sjøli; Øverbye, Knut Eiliv Ødegård; Kransberg, Jonas Moe; Sørensen, Øystein & Garrido, Pablo F. [Show all 19 contributors for this article] (2026). Feature-specific environmental contributions to human cortical architecture revealed by twin brainprints. Communications Biology. doi: 10.1038/s42003-026-10707-w. Full text in Research Archive Show summary

  Abstract How environmental variation shapes the human cerebral cortex remains incompletely understood. Here we compare cortical brainprints – individual profiles of regional cortical morphology – in 210 twins (age 16-78 years) to distinguish prenatal, adult naturalistic and experimentally induced environmental variation from genetic contributions. Monozygotic twins showed higher brainprint similarity than dizygotic twins, consistent with genetic effects. Lasting influences of early environment were evident in lower brainprint similarity in monozygotic twin-pairs with greater birthweight discordances, driven by surface area across the cortical ribbon. In contrast, within-pair differences in adult weight and lifestyle had minimal influence. Still, a 10-week virtual-reality navigation intervention revealed training-induced changes in the gray-white interface, with curvature and area changes supported by microstructural reconfigurations. Relative brainprint similarity increased in monozygotic but diverged in dizygotic pairs following training. These findings show that distinct environmental influences acting at prenatal and adult stages are reflected in different features of the human cerebral cortex.

• Jarholm, Jonas Alexander; Teceläo, Sandra Raquel Ramos; Kirsebom, Bjørn-Eivind; Ghazi, Mostafa Mehdipour; Pålhaugen, Lene & Gisladottir, Berglind [Show all 17 contributors for this article] (2026). Independent prognostic value of peak width of skeletonized mean diffusivity on clinical progression in Alzheimer's disease. Alzheimer's and Dementia: Diagnosis, Assessment and Disease Monitoring. 18(3). doi: 10.1002/dad2.70416. Full text in Research Archive Show summary

  INTRODUCTION Peak width of skeletonized mean diffusivity (PSMD) is a candidate magnetic resonance imaging marker for global white matter integrity. We investigated the value of PSMD in predicting clinical progression in amyloid-positive and amyloid-negative individuals. METHODS PSMD, cognition, and amyloid status were measured in 254 subjects from the Dementia Disease Initiation (DDI) cohort and 211 subjects from the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort. Survival analysis was conducted on 166 DDI subjects and validated in 178 ADNI subjects using Clinical Dementia Rating scale. RESULTS High PSMD amyloid-positive individuals had an increased risk of clinical progression relative to those with low PSMD, driven by independent additive effects of amyloid pathology and PSMD. Higher PSMD was predominantly associated with slower processing speed and reduced executive function, but not with memory performance. DISCUSSION Combining PSMD with amyloid status may improve the prediction of clinical progression in Alzheimer's disease, particularly in relation to executive and processing speed domains.

• Bratsberg, Bernt Magne; Fjell, Anders Martin; Røgeberg, Ole Jørgen & Walhovd, Kristine Beate (2026). Educational expansion and the hidden reversal of the Flynn effect—Differential trends across socioeconomic strata. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 123(28). doi: 10.1073/pnas.2536089123. Full text in Research Archive
• Grødem, Edvard Olaf Sætersdal; Pineiro, Didac Vidal; Sørensen, Øystein; Bartrés-Faz, David; Brandmaier, Andreas M. & Cattaneo, Gabriele [Show all 20 contributors for this article] (2026). Stable individual differences dominate adult brain volume variation until later life. Imaging Neuroscience. 4. doi: 10.1162/IMAG.a.1242. Full text in Research Archive
• Garrido, Pablo Fernandez; Bråthen, Anne Cecilie Sjøli; Falch, Emilie Sogn; Kransberg, Jonas Moe; Fjell, Anders Martin & Sørensen, Øystein [Show all 7 contributors for this article] (2026). Unwrapping the mirror tracing task. Behavior Research Methods. ISSN 1554-351X. 58. doi: 10.3758/s13428-025-02845-6. Full text in Research Archive Show summary

  The Mirror Tracing Task (MTT) is a method used to study visuomotor skills learning. It is traditionally evaluated by counting the number of times a person draws outside of the borders of a figure, typically a star, while looking at its mirror reflection. While insightful for overall performance, this metric lacks a precise analysis of the tracing, such as details on errors in specific regions. We propose a new MTT analysis method that studies the drawing as a function of the angle around the figure’s center. Two new variables are introduced: residuals, which measure deviation from the ideal drawing, and density, which measures how often a specific path is retraced. These variables are defined per angle or region, allowing a more detailed analysis, highlighting the most challenging parts of the drawing for each person, and enabling comparison across trials or finding common patterns between individuals. We applied this approach to the first MTT trial of 210 participants using age as a variable of interest. Residuals and density were summarized as a single value and compared with the traditional approach, providing similar results. When analyzed as a function of the angle, these variables enabled the identification of specific regions of the star where the errors are age-sensitive. Additionally, a time series-like approach enabled us to cluster drawings and quantify their similarity. The code used for this new method has been made openly accessible to make it easier for its applications in new research or the reanalysis of previous projects.

• Rahimi-Eichi, Habiballah; Baker, Justin T.; Fjell, Anders Martin & Buckner, Randy L. (2025). Age- and sex-related differences in sleep patterns and their relations to self-reported sleep and mood. SLEEP Advances. 6(4). doi: 10.1093/sleepadvances/zpaf079. Full text in Research Archive
• Demnitz, Naiara; Baare, William F.C.; Binnewies, Julia; Brandmaier, Andreas; Fjell, Anders Martin & Gates, Anne T. [Show all 17 contributors for this article] (2025). No significant association between self-reported physical activity and brain volumes in women and men from five European cohorts. Alzheimer's & Dementia. ISSN 1552-5260. 21. doi: 10.1002/alz70860_097396. Full text in Research Archive
• Pineiro, Didac Vidal; Sørensen, Øystein; Strømstad, Marie Lorentsen; Amlien, Inge; Baaré, William & Bartrés-Faz, David [Show all 74 contributors for this article] (2025). Vulnerability to memory decline in aging revealed by a mega-analysis of structural brain change. Nature Communications. 16(1). doi: 10.1038/s41467-025-66354-y. Full text in Research Archive Show summary

  Brain atrophy is a key factor behind episodic memory loss in aging, but the nature and ubiquity of this relationship remains poorly understood. This study leverages 13 longitudinal datasets, including 3737 cognitively healthy adults (10,343 MRI scans; 13,460 memory assessments), to determine whether brain change-memory change associations are more pronounced with age and genetic risk for Alzheimer’s Disease. Both factors are associated with accelerated brain decline, yet it remains unclear whethermemory loss is exacerbated beyond what atrophy alone would predict. Additionally, we assess whether memory decline aligns with a global pattern of atrophy or stems from distinct regional contributions. Our mega-analysis reveals a nonlinear relationship between memory decline and brain atrophy, primarily affecting individuals with above-average brain structural decline. The associations are stronger in the hippocampus but also spread across diverse cortical and subcortical regions. The associations strengthen with age, reachingmoderate associations in participants in their eighties. While APOE ε4 carriers exhibit steeper brain and memory loss, genetic risk has no effect on the change-change associations. These findings support the presence of common biological macrostructural substrates underlying memory function in older age which are vulnerable to multiple age-related factors, even in the absence of overt pathological changes.

• Demnitz, Naiara; Baaré, William F.C.; Binnewies, Julia; Brandmaier, Andreas M.; Fjell, Anders Martin & Gates, Anne T. [Show all 17 contributors for this article] (2025). No significant association between self-reported physical activity and brain volumes in women and men from five European cohorts. Scientific Reports. 15(1). doi: 10.1038/s41598-025-98601-z. Full text in Research Archive Show summary

  Various studies have reported an association between physical activity and grey matter volumes. Some studies have suggested that this relationship may be moderated by sex, yet the direction is still under debate. Focusing on hippocampus and dorsolateral prefrontal cortex (dlPFC), we tested whether the association between regional grey matter volumes and self-reported physical activity differs between women and men. We examined this interaction in five European cohorts from the Lifebrain consortium (n = 1809; age range: 18–88 years). Effect sizes were first determined by linear models run separately for each cohort, then pooled across datasets in a random-effects meta-analysis. Contrary to our hypotheses, there was no evidence of a relationship between physical activity and hippocampal or dlPFC volumes, nor was there a moderation by sex. Our null findings raise the question of whether self-report questionnaires of physical activity, which commonly feature in big datasets, are sufficiently sensitive to capture a—presumably modest—association between physical activity levels and grey matter outcomes. We conclude that the reliance on self-report questionnaires of physical activity is sub-optimal for brain-behaviour analyses.

• Padrela, Beatriz E.; Teceläo, Sandra Raquel Ramos; Kirsebom, Bjørn-Eivind; Geier, Oliver Marcel; Tranfa, Mario & Masserini, Federico [Show all 22 contributors for this article] (2025). Blood-brain barrier water exchange in relation to amyloid, cognition and cerebrovascular burden. NeuroImage: Clinical. 49. doi: 10.1016/j.nicl.2025.103926. Full text in Research Archive Show summary

  Blood-brain barrier (BBB) water exchange may serve as a sensitive early biomarker for Alzheimer’s disease and age-related cognitive decline. This study applied a non-invasive multi-echo arterial spin labeling (ASL) technique to measure BBB water exchange time (Tex), cerebral blood flow (CBF), and arterial transit time (ATT) in 160 adults aged 50 years and older. Participants were classified as cognitively normal (CN), having subjective cognitive decline (SCD), or mild cognitive impairment (MCI). They were assessed for amyloid status and cerebrovascular burden. Compared to CN participants, Tex was significantly lower in both SCD (−9.5 %) and MCI (−14.5 %) groups, suggesting that reductions in BBB water exchange emerge early in the course of cognitive decline. In contrast, CBF was reduced only in MCI participants (−20.8 % compared to CN), and ATT was significantly increased only in individuals with severe cerebrovascular burden (Fazekas score 3). Notably, Tex showed a stepwise decrease with increasing Fazekas scores (1–2), supporting its sensitivity to moderate small vessel disease. No associations were found between Tex and amyloid positivity after adjusting for age and sex. These findings indicate that Tex alterations may precede changes in traditional perfusion markers and are more closely related to vascular and early cognitive changes than to amyloid pathology. BBB water exchange mapping may therefore provide a promising, non-invasive tool to detect early neurovascular dysfunction that contributes to cognitive decline in aging populations, potentially offering a useful biomarker for early intervention trials targeting vascular contributions to dementia.

• Fjell, Anders Martin; Røgeberg, Ole Jørgen; Sørensen, Øystein; Amlien, Inge; Bartrés-Faz, David & Brandmaier, Andreas M. [Show all 23 contributors for this article] (2025). Reevaluating the role of education on cognitive decline and brain aging in longitudinal cohorts across 33 Western countries. Nature Medicine. ISSN 1078-8956. 31, p. 2967–2976. doi: 10.1038/s41591-025-03828-y. Full text in Research Archive Show summary

  Why education is linked to higher cognitive function in aging is fiercely debated. Leading theories propose that education reduces brain decline in aging and enhances tolerance to brain pathology or that it does not affect cognitive decline but, rather, reflects higher early-life cognitive function. To test these theories, we analyzed 407,356 episodic memory scores from 170,795 participants older than 50 years, alongside 15,157 brain magnetic resonance imaging scans from 6,472 participants across 33 Western countries. More education was associated with better memory, larger intracranial volume and slightly larger volume of memory-sensitive brain regions. However, education did not protect against age-related decline or weakened effects of brain decline on cognition. The most parsimonious explanation for the results is that the associations reflect factors present early in life, including propensity of individuals with certain traits to pursue more education. Although education has numerous benefits, the notion that it provides protection against cognitive or brain decline is not supported. In a large cross-national study, education was linked to better memory and larger brain volumes but not to slower cognitive or brain decline with age, suggesting that the association reflects early-life factors rather than neuroprotective effects in aging.

• Raud, Liisa; Smits, Martijn Johannes Bernardus; Sneve, Markus Handal; Ness, Hedda Tvedten; Folvik, Line & Rasch, Björn [Show all 7 contributors for this article] (2025). Differential expression of spatiotemporal sleep spindle clusters in aging. SLEEP Advances. 6(4). doi: 10.1093/sleepadvances/zpaf084. Full text in Research Archive
• Ravndal, Anne; Fjell, Anders Martin; Vidal-Piñeiro, Didac; Sørensen, Øystein; Falch, Emilie Sogn & Kropiunig, Julia [Show all 21 contributors for this article] (2025). Sex differences in healthy brain aging are unlikely to explain higher Alzheimer’s disease prevalence in women. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 122(42). doi: 10.1073/pnas.2510486122. Full text in Research Archive Show summary

  As Alzheimer’s disease (AD) is diagnosed more frequently in women, understanding the role of sex has become a key priority in AD research. However, despite aging being the primary risk factor for AD, it remains unclear whether men and women differ in the extent of brain decline with age. Using 12,638 longitudinal brain MRIs from 4,726 participants aged 17 to 95 y across 14 cohorts, we examined sex differences in structural brain changes over time, controlling for differences in head size. Men showed greater cortical thickness (CT) decline in the cuneus, lingual, parahippocampal, and pericalcarine regions; surface area decline in the fusiform and postcentral regions; and in older adults, greater subcortical decline in the caudate, nucleus accumbens, putamen, and pallidum. In contrast, women only showed greater surface area decline in the banks of the superior temporal sulcus and greater ventricular expansion in older adults. These results suggest that sex differences in age-related brain decline are unlikely to contribute to the higher AD diagnosis prevalence in women, necessitating research into alternative explanations.

• Vidal-Piñeiro, Didac; Sørensen, Øystein; Strømstad, Marie Lorentsen; Amlien, Inge; Anderson, Micael & Baaré, William F.C. [Show all 25 contributors for this article] (2025). Reliability of structural brain change in cognitively healthy adult samples. Imaging Neuroscience. 3, p. 1–25. doi: 10.1162/imag_a_00547. Full text in Research Archive Show summary

  In neuroimaging research, tracking individuals over time is key to understanding the interplay between brain changes and genetic, environmental, or cognitive factors across the lifespan. Yet, the extent to which we can estimate the individual trajectories of brain change over time with precision remains uncertain. In this study, we estimated the reliability of structural brain change in cognitively healthy adults from multiple samples and assessed the influence of follow-up time and number of observations. Estimates of cross-sectional measurement error and brain change variance were obtained using the longitudinal FreeSurfer processing stream. Our findings showed, on average, modest longitudinal reliability with 2 years of follow-up. Increasing the follow-up time was associated with a substantial increase in longitudinal reliability, while the impact of increasing the number of observations was comparatively minor. On average, 2-year follow-up studies require ≈2.7 and ≈4.0 times more individuals than designs with follow-ups of 4 and 6 years to achieve comparable statistical power. Subcortical volume exhibited higher longitudinal reliability than cortical area, thickness, and volume. The reliability estimates were comparable with those estimated from empirical data. The reliability estimates were affected by both the cohort’s age where younger adults had lower reliability of change and the preprocessing pipeline where the FreeSurfer’s longitudinal stream was notably superior than the cross-sectional stream. Suboptimal reliability inflated sample size requirements and compromised the ability to distinguish individual trajectories of brain aging. This study underscores the importance of long-term follow-ups and the need to consider reliability in longitudinal neuroimaging research.

• Grydeland, Håkon; Sneve, Markus Handal; Roe, James Michael; Raud, Liisa; Ness, Hedda Tvedten & Folvik, Line [Show all 12 contributors for this article] (2025). Network segregation during episodic memory shows age-invariant relations with memory performance from 7 to 82 years. Neurobiology of Aging. ISSN 0197-4580. 148, p. 1–15. doi: 10.1016/j.neurobiolaging.2025.01.004. Full text in Research Archive Show summary

  Lower episodic memory capability, as seen in development and aging compared with younger adulthood, may partly depend on lower brain network segregation. Here, our objective was twofold: (1) test this hypothesis using within- and between-network functional connectivity (FC) during episodic memory encoding and retrieval, in two independent samples (n = 734, age 7–82 years). (2) Assess associations with age and the ability to predict memory comparing task-general FC and memory-modulated FC. In a multiverse-inspired approach, we performed tests across multiple analytic choices. Results showed that relationships differed based on these analytic choices and were mainly present in the largest dataset,. Significant relationships indicated that (i) memory-modulated FC predicted memory performance and associated with memory in an age-invariant manner. (ii) In line with the so-called neural dedifferentiation view, task-general FC showed lower segregation with higher age in adults which was associated with worse memory performance. In development, although there were only weak signs of a neural differentiation, that is, gradually higher segregation with higher age, we observed similar lower segregation-worse memory relationships. This age-invariant relationships between FC and episodic memory suggest that network segregation is pivotal for memory across the healthy lifespan.

• Lorentzen, Ingrid Myrvoll; Espenes, Johan Jacob; Eliassen, Ingvild Vøllo; Hessen, Erik; Waterloo, Knut & Timón-Reina, Santiago [Show all 10 contributors for this article] (2025). Norwegian normative data for regression-based D-KEFS color-word interference test derived measures and comparison to conventional contrast measures. Applied neuropsychology: Adult. ISSN 2327-9095. doi: 10.1080/23279095.2025.2462605. Full text in Research Archive
• Padrela, Beatriz E.; Slivka, Maksim; Sneve, Markus Handal; Garrido, Pablo F.; Dijsselhof, Mathijs B.J. & Hageman, Tamara [Show all 18 contributors for this article] (2025). Blood-brain barrier water permeability across the adult lifespan: A multi-echo ASL study. Neurobiology of Aging. ISSN 0197-4580. 147, p. 176–186. doi: 10.1016/j.neurobiolaging.2024.12.012. Full text in Research Archive
• Fjell, Anders Martin; Sneve, Markus Handal; Amlien, Inge; Grydeland, Håkon; Mowinckel, Athanasia Monika & Vidal-Piñeiro, Didac [Show all 8 contributors for this article] (2025). Stable hippocampal correlates of high episodic memory function across adulthood. Scientific Reports. 15(1). doi: 10.1038/s41598-025-92278-0. Full text in Research Archive
• Fjell, Anders Martin & Walhovd, Kristine B (2025). Sleep Patterns and Human Brain Health. The Neuroscientist. ISSN 1073-8584. doi: 10.1177/10738584241309850. Full text in Research Archive
• Capogna, Elettra; Sørensen, Øystein; Watne, Leiv; Roe, James Michael; Strømstad, Marie Lorentsen & Idland, Ane-Victoria [Show all 12 contributors for this article] (2025). Subtypes of brain change in aging and their associations with cognition and Alzheimer’s disease biomarkers. Neurobiology of Aging. ISSN 0197-4580. 147, p. 124–140. doi: 10.1016/j.neurobiolaging.2024.12.009. Full text in Research Archive Show summary

  Structural brain changes underlie cognitive changes and interindividual variability in cognition in older age. By using structural MRI data-driven clustering, we aimed to identify subgroups of cognitively unimpaired older adults based on brain change patterns and assess how changes in cortical thickness, surface area, and subcortical volume relate to cognitive change. We tested (1) which brain structural changes predict cognitive change (2) whether these are associated with core cerebrospinal fluid (CSF) Alzheimer’s disease biomarkers, and (3) the degree of overlap between clusters derived from different structural modalities in 1899 cognitively healthy older adults followed up to 16 years. We identified four groups for each brain feature, based on the degree of a main longitudinal component of decline. The minimal overlap between features suggested that each contributed uniquely and independently to structural brain changes in aging. Cognitive change and baseline cognition were associated with cortical area change, whereas higher baseline levels of phosphorylated tau and amyloid-β related to changes in subcortical volume. These results may contribute to a better understanding of different aging trajectories.

• Walhovd, Kristine B; Krogsrud, Stine Kleppe; Amlien, Inge; Sørensen, Øystein; Wang, Yunpeng & Bråthen, Anne Cecilie Sjøli [Show all 14 contributors for this article] (2024). Fetal influence on the human brain through the lifespan. eLIFE. 12. doi: 10.7554/eLife.86812. Full text in Research Archive
• Roe, James Michael; Vidal-Piñeiro, Didac; Sørensen, Øystein; Grydeland, Håkon; Leonardsen, Esten Høyland & Iakunchykova, Olena [Show all 35 contributors for this article] (2024). Brain change trajectories in healthy adults correlate with Alzheimer’s related genetic variation and memory decline across life. Nature Communications. 15(1). doi: 10.1038/s41467-024-53548-z. Full text in Research Archive Show summary

  Throughout adulthood and ageing our brains undergo structural loss in an average pattern resembling faster atrophy in Alzheimer’s disease (AD). Using a longitudinal adult lifespan sample (aged 30-89; 2–7 timepoints) and four polygenic scores for AD, we show that change in AD-sensitive brain features correlates with genetic AD-risk and memory decline in healthy adults. We first show genetic risk links with more brain loss than expected for age in early Braak regions, and find this extends beyond APOE genotype. Next, we run machine learning on AD-control data from the Alzheimer’s Disease Neuroimaging Initiative using brain change trajectories conditioned on age, to identify AD-sensitive features and model their change in healthy adults. Genetic AD-risk linked with multivariate change across many AD-sensitive features, and we show most individuals over age ~50 are on an accelerated trajectory of brain loss in AD-sensitive regions. Finally, high genetic risk adults with elevated brain change showed more memory decline through adulthood, compared to high genetic risk adults with less brain change. Our findings suggest quantitative AD risk factors are detectable in healthy individuals, via a shared pattern of ageing- and AD-related neurodegeneration that occurs along a continuum and tracks memory decline through adulthood.

• Ness, Hedda Tvedten; Folvik, Line; Sneve, Markus Handal; Grydeland, Håkon; Vidal-Piñeiro, Didac & Raud, Liisa [Show all 9 contributors for this article] (2024). Recalled through this day but forgotten next week?-retrieval activity predicts durability of partly consolidated memories. Cerebral Cortex. ISSN 1047-3211. 34(6), p. 1–15. doi: 10.1093/cercor/bhae233. Full text in Research Archive
• Fjell, Anders Martin & Walhovd, Kristine B (2024). Individual sleep need is flexible and dynamically related to cognitive function. Nature Human Behaviour. doi: 10.1038/s41562-024-01827-6. Full text in Research Archive
• Grødem, Edvard Olaf Sætersdal; Leonardsen, Esten Høyland; MacIntosh, Bradley; Bjørnerud, Atle; SCHELLHORN, TILL & Sørensen, Øystein [Show all 8 contributors for this article] (2024). A minimalistic approach to classifying Alzheimer's disease using simple and extremely small convolutional neural networks. Journal of Neuroscience Methods. ISSN 0165-0270. 411. doi: 10.1016/j.jneumeth.2024.110253. Full text in Research Archive
• Fjell, Anders Martin (2024). Aging Brain from a Lifespan Perspective. Current Topics in Behavioral Neurosciences. ISSN 1866-3370. 68, p. 349–370. doi: 10.1007/7854_2024_476. Full text in Research Archive
• Kransberg, Jonas; Sneve, Markus Handal; Falch, Emilie Sogn; Bråthen, Anne Cecilie Sjøli; Fjell, Anders Martin & Walhovd, Kristine B (2024). Failure to replicate detection of grid-cell like representations in human fMRI. Alzheimer's & Dementia. ISSN 1552-5260. 20, p. e086080–e086080. doi: 10.1002/alz.086080. Full text in Research Archive
• Bratsberg, Bernt Magne; Fjell, Anders Martin; Røgeberg, Ole; Skirbekk, Vegard Fykse & Walhovd, Kristine B (2024). Differences in cognitive function at 18 y of age explain the association between low education and early dementia risk. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 121(41). doi: 10.1073/pnas.2412017121. Full text in Research Archive Show summary

  Major initiatives attempt to prevent dementia by targeting modifiable risk factors. Low education is frequently pointed to, due to its relationship with dementia. Impact of education is difficult to assess, however, because of associations with multiple other factors, requiring large population-representative samples to tease the relationships apart. We studied 207,814 Norwegian men born between 1950 and 1959 who underwent compulsory cognitive testing during military conscription as young adults, to systematically test associations of education, cognition, and other important factors. Participants were grouped into five education levels and seven cognitive levels. A total of 1,521 were diagnosed with dementia between ages 60 and 69 y. While having compulsory education only was associated with increased risk (Hazard ratio [HR] = 1.37, CI: 1.17 to 1.60), this association was markedly attenuated when controlling for cognitive test scores (HR = 1.08, CI: 0.91 to 1.28). In contrast, low cognitive score was associated with double risk of later diagnosis, even when controlling for education (HR = 2.00, CI: 1.65 to 2.42). This relationship survived controlling for early-life socioeconomic status and replicated within pairs of brothers. This suggests that genetic and environmental factors shared within families, e.g., common genetics, parental education, socioeconomic status, or other shared experiences, cannot account for the association. Rather, independent, nonfamilial factors are more important. In contrast, within-family factors accounted for the relationship between low education and diagnosis risk. In conclusion, implementing measures to increase cognitive function in childhood and adolescence appears to be a more promising strategy for reducing dementia burden.

• Iakunchykova, Olena; Pan, Mengyu; Amlien, Inge; Roe, James Michael; Walhovd, Kristine B & Fjell, Anders Martin [Show all 9 contributors for this article] (2024). Genetic evidence for the causal effects of C–reactive protein on self-reported habitual sleep duration. Brain, Behavior, and Immunity - Health (BBI - Health). 37. doi: 10.1016/j.bbih.2024.100754. Full text in Research Archive
• Pan, Mengyu; Roe, James Michael; Nudel, Ron; Schork, Andrew J.; Iakunchykova, Olena & Fjell, Anders Martin [Show all 11 contributors for this article] (2023). Circulating S100B levels at birth and risk of six major neuropsychiatric or neurological disorders: a two-sample Mendelian Randomization Study. Translational Psychiatry. 13(1). doi: 10.1038/s41398-023-02478-3. Full text in Research Archive
• Binnewies, Julia; Nawijn, Laura; Brandmaier, Andreas M.; Baaré, William F.C.; Boraxbekk, Carl-Johan & Demnitz, Naiara [Show all 15 contributors for this article] (2023). Lifestyle-related risk factors and their cumulative associations with hippocampal and total grey matter volume across the adult lifespan: A pooled analysis in the European Lifebrain consortium. Brain Research Bulletin. ISSN 0361-9230. 200. doi: 10.1016/j.brainresbull.2023.110692. Full text in Research Archive Show summary

  Background Lifestyle-related risk factors, such as obesity, physical inactivity, short sleep, smoking and alcohol use, have been associated with low hippocampal and total grey matter volumes (GMV). However, these risk factors have mostly been assessed as separate factors, leaving it unknown if variance explained by these factors is overlapping or additive. We investigated associations of five lifestyle-related factors separately and cumulatively with hippocampal and total GMV, pooled across eight European cohorts. Methods We included 3838 participants aged 18–90 years from eight cohorts of the European Lifebrain consortium. Using individual person data, we performed cross-sectional meta-analyses on associations of presence of lifestyle-related risk factors separately (overweight/obesity, physical inactivity, short sleep, smoking, high alcohol use) as well as a cumulative unhealthy lifestyle score (counting the number of present lifestyle-related risk factors) with FreeSurfer-derived hippocampal volume and total GMV. Lifestyle-related risk factors were defined according to public health guidelines. Results High alcohol use was associated with lower hippocampal volume (r = −0.10, p = 0.021), and overweight/obesity with lower total GMV (r = −0.09, p = 0.001). Other lifestyle-related risk factors were not significantly associated with hippocampal volume or GMV. The cumulative unhealthy lifestyle score was negatively associated with total GMV (r = −0.08, p = 0.001), but not hippocampal volume (r = −0.01, p = 0.625). Conclusions This large pooled study confirmed the negative association of some lifestyle-related risk factors with hippocampal volume and GMV, although with small effect sizes. Lifestyle factors should not be seen in isolation as there is evidence that having multiple unhealthy lifestyle factors is associated with a linear reduction in overall brain volume.

• Espenes, Johan Jacob; Lorentzen, Ingrid Myrvoll; Eliassen, Ingvild Vøllo; Hessen, Erik; Waterloo, Knut K & Timón, Santiago [Show all 10 contributors for this article] (2023). Regression-based normative data for the D-KEFS Color-Word Interference Test in Norwegian adults ages 20–85. The Clinical Neuropsychologist. ISSN 1385-4046. doi: 10.1080/13854046.2023.2276967. Full text in Research Archive Show summary

  <p><i>Objective:</i> The Delis-Kaplan Executive Function System (D-KEFS) Color-Word-Interference Test (CWIT; AKA Stroop test) is a widely used measure of processing speed and executive function. While test materials and instructions have been translated to Norwegian, only American age-adjusted norms from D-KEFS are available in Norway. We here develop norms in a sample of 1011 Norwegians between 20 and 85 years. We provide indexes for stability over time and assess demographic adjustments applying the D-KEFS norms. <p><i>Method:</i> Participants were healthy Norwegian adults from Center for Lifespan Changes in Brain and Cognition (LCBC) (n = 899), the Dementia Disease Initiation (n = 77), and Oslo MCI (n = 35). Using regression-based norming, we estimated linear and non-linear effects of age, education, and sex on the CWIT 1-4 subtests. Stability over time was assessed with intraclass correlation coefficients (ICC). The normative adjustment of the D-KEFS norms was assessed with linear regression models. <p><i>Results:</i> Increasing age was associated with slower completion on all CWIT subtests in a non-linear fashion (accelerated lowering of performance with older age). Women performed better on CWIT-1&3. Higher education predicted faster completion time on CWIT-3&4. The original age-adjusted norms from D-KEFS did not adjust for sex or education. Furthermore, we observed significant, albeit small effects of age on all CWIT subtests. ICC analyses indicated moderate to good stability over time. <p><i>Conclusion:</i> We present demographically adjusted regression-based norms and stability indexes for the D-KEFS CWIT subtests. US D-KEFS norms may be inaccurate for Norwegians with high or low educational attainment, especially women.

• Walhovd, Kristine B; Lövden, Martin & Fjell, Anders Martin (2023). Timing of lifespan influences on brain and cognition. Trends in Cognitive Sciences. ISSN 1364-6613. 27(10), p. 901–915. doi: 10.1016/j.tics.2023.07.001. Full text in Research Archive
• Aksnes, Mari; Capogna, Elettra; Vidal-Piñeiro, Didac; Chaudhry, Farrukh Abbas; Myrstad, Marius & Idland, Ane-Victoria [Show all 13 contributors for this article] (2023). Matrix metalloproteinases are associated with brain atrophy in cognitively unimpaired individuals. Neurobiology of Aging. ISSN 0197-4580. 131, p. 11–23. doi: 10.1016/j.neurobiolaging.2023.05.012. Full text in Research Archive Show summary

  Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) have been linked to age-related neurodegeneration and Alzheimer’s disease (AD), but their role in normal aging is poorly understood. We used linear mixed models to determine if baseline or rate of yearly change in cerebrospinal fluid (CSF) levels of MMP-2; MMP-3; MMP-10; TIMP-123 (composite of TIMP-1, TIMP-2, and TIMP-3); or TIMP-4 predicted changes in bilateral entorhinal cortex thickness, hippocampal volume, or lateral ventricle volume in cognitively unimpaired individuals. We also assessed effects on the CSF AD biomarkers amyloid-β42 and phosphorylated tau181. Low baseline levels of MMP-3 predicted larger ventricle volumes and more entorhinal cortex thinning. Increased CSF MMP-2 levels over time predicted more entorhinal thinning, hippocampal atrophy, and ventricular expansion, while increased TIMP-123 over time predicted ventricular expansion. No MMP/TIMPs predicted changes in CSF AD biomarkers. Notably, we show for the first time that longitudinal increases in MMP-2 and TIMP-123 levels may predict age-associated brain atrophy. In conclusion, MMPs and TIMPs may play a role in brain atrophy in cognitively unimpaired aging.

• Folvik, Line; Sneve, Markus Handal; Ness, Hedda Tvedten; Vidal-Piñeiro, Didac; Raud, Liisa & Geier, Oliver [Show all 8 contributors for this article] (2023). Sustained upregulation of widespread hippocampal-neocortical coupling following memory encoding. Cerebral Cortex. ISSN 1047-3211. 33(8), p. 4844–4858. doi: 10.1093/cercor/bhac384. Full text in Research Archive
• Fjell, Anders Martin; Sørensen, Øystein; Wang, Yunpeng; Amlien, Inge; Baaré, William F. C. & Bartrés-Faz, David [Show all 24 contributors for this article] (2023). No phenotypic or genotypic evidence for a link between sleep duration and brain atrophy. Nature Human Behaviour. 7, p. 2008–2022. doi: 10.1038/s41562-023-01707-5. Full text in Research Archive Show summary

  Abstract Short sleep is held to cause poorer brain health, but is short sleep associated with higher rates of brain structural decline? Analysing 8,153 longitudinal MRIs from 3,893 healthy adults, we found no evidence for an association between sleep duration and brain atrophy. In contrast, cross-sectional analyses (51,295 observations) showed inverse U-shaped relationships, where a duration of 6.5 (95% confidence interval, (5.7, 7.3)) hours was associated with the thickest cortex and largest volumes relative to intracranial volume. This fits converging evidence from research on mortality, health and cognition that points to roughly seven hours being associated with good health. Genome-wide association analyses suggested that genes associated with longer sleep for below-average sleepers were linked to shorter sleep for above-average sleepers. Mendelian randomization did not yield evidence for causal impacts of sleep on brain structure. The combined results challenge the notion that habitual short sleep causes brain atrophy, suggesting that normal brains promote adequate sleep duration—which is shorter than current recommendations.

• Roe, James Michael; Vidal-Piñeiro, Didac; Amlien, Inge; Pan, Mengyu; Sneve, Markus Handal & Schotten, Michel Thiebaut de [Show all 14 contributors for this article] (2023). Tracing the development and lifespan change of population-level structural asymmetry in the cerebral cortex. eLIFE. 12, p. 1–32. doi: 10.7554/eLife.84685. Full text in Research Archive
• Raud, Liisa; Sneve, Markus Handal; Vidal-Piñeiro, Didac; Sørensen, Øystein; Folvik, Line & Ness, Hedda Tvedten [Show all 10 contributors for this article] (2023). Hippocampal-cortical functional connectivity during memory encoding and retrieval. NeuroImage. ISSN 1053-8119. 279. doi: 10.1016/j.neuroimage.2023.120309. Full text in Research Archive
• Ljøsne, Isabelle Sylvie Budin; Friedman, Barbara Bodorkos; Baaré, William F. C.; Bartrés-Faz, David; Carver, Rebecca Bruu & Drevon, Christian André [Show all 17 contributors for this article] (2023). Stakeholder engagement in European brain research: Experiences of the Lifebrain consortium. Health Expectations. ISSN 1369-6513. 26(3), p. 1318–1326. doi: 10.1111/hex.13747. Full text in Research Archive Show summary

  Introduction Stakeholder engagement remains scarce in basic brain research. However, it can greatly improve the relevance of investigations and accelerate the translation of study findings to policy. The Lifebrain consortium investigated risk and protective factors influencing brain health using cognition, lifestyle and imaging data from European cohorts. Stakeholder activities of Lifebrain—organized in a separate work package—included organizing stakeholder events, investigating public perceptions of brain health and dissemination. Here, we describe the experiences of researchers and stakeholders regarding stakeholder engagement in the Lifebrain project. Methods Stakeholder engagement in Lifebrain was evaluated through surveys among researchers and stakeholders and stakeholders' feedback at stakeholder events through evaluation forms. Survey data were analysed using a simple content analysis approach, and results from evaluation forms were summarized after reviewing the frequency of responses. Results Consortium researchers and stakeholders experienced the engagement activities as meaningful and relevant. Researchers highlighted that it made the research and research processes more visible and contributed to new networks, optimized data collection on brain health perceptions and the production of papers and provided insights into stakeholder views. Stakeholders found research activities conducted in the stakeholder engagement work package to be within their field of interest and research results relevant to their work. Researchers identified barriers to stakeholder engagement, including lack of time, difficulties in identifying relevant stakeholders, and challenges in communicating complex scientific issues in lay language and maintaining relationships with stakeholders over time. Stakeholders identified barriers such as lack of budget, limited resources in their organization, time constraints and insufficient communication between researchers and stakeholders. Conclusion Stakeholder engagement in basic brain research can greatly benefit researchers and stakeholders alike. Its success is conditional on dedicated human and financial resources, clear communication, transparent mutual expectations and clear roles and responsibilities. Public Contribution Patient organizations, research networks, policymakers and members of the general public were involved in engagement and research activities throughout the project duration.

• Sørensen, Øystein; Fjell, Anders Martin & Walhovd, Kristine B (2023). Longitudinal Modeling of Age-Dependent Latent Traits with Generalized Additive Latent and Mixed Models. Psychometrika. ISSN 0033-3123. 88(2), p. 456–486. doi: 10.1007/s11336-023-09910-z. Full text in Research Archive
• Capogna, Elettra; Watne, Leiv; Sørensen, Øystein; Guichelaar, Carlijn Jamila; Idland, Ane-Victoria & Halaas, Nathalie Bodd [Show all 11 contributors for this article] (2023). Associations of neuroinflammatory IL-6 and IL-8 with brain atrophy, memory decline, and core AD biomarkers – in cognitively unimpaired older adults. Brain, Behavior, and Immunity. ISSN 0889-1591. 113, p. 56–65. doi: 10.1016/j.bbi.2023.06.027. Full text in Research Archive Show summary

  Concentrations of pro-inflammatory cytokines –interleukin-6 (IL-6) and interleukin-8 (IL-8) – are increased with age and in Alzheimer’s disease (AD). It is not clear whether concentrations of IL-6 and IL-8 in the central nervous system predict later brain and cognitive changes over time nor whether this relationship is mediated by core AD biomarkers. Here, 219 cognitively healthy older adults (62–91 years), with baseline cerebrospinal fluid (CSF) measures of IL-6 and IL-8 were followed over time – up to 9 years – with assessments that included cognitive function, structural magnetic resonance imaging, and CSF measurements of phosphorylated tau (p-tau) and amyloid-β (Aβ-42) concentrations (for a subsample). Higher baseline CSF IL-8 was associated with better memory performance over time in the context of lower levels of CSF p-tau and p-tau/Aβ-42 ratio. Higher CSF IL-6 was related to less CSF p-tau changes over time. The results are in line with the hypothesis suggesting that an up-regulation of IL-6 and IL-8 in the brain may play a neuroprotective role in cognitively healthy older adults with lower load of AD pathology.

• Fjell, Anders Martin; Sørensen, Øystein; Wang, Yunpeng; Amlien, Inge; Baaré, William F C & Bartrés-Faz, David [Show all 21 contributors for this article] (2023). Is Short Sleep Bad for the Brain? Brain Structure and Cognitive Function in Short Sleepers. Journal of Neuroscience. ISSN 0270-6474. 43(28), p. 5241–5250. doi: 10.1523/JNEUROSCI.2330-22.2023. Full text in Research Archive Show summary

  Many sleep less than recommended without experiencing daytime sleepiness. According to prevailing views, short sleep increases risk of lower brain health and cognitive function. Chronic mild sleep deprivation could cause undetected sleep debt, negatively affecting cognitive function and brain health. However, it is possible that some have less sleep need and are more resistant to negative effects of sleep loss. We investigated this using a cross-sectional and longitudinal sample of 47,029 participants of both sexes (20–89 years) from the Lifebrain consortium, Human Connectome project (HCP) and UK Biobank (UKB), with measures of self-reported sleep, including 51,295 MRIs of the brain and cognitive tests. A total of 740 participants who reported to sleep &lt;6 h did not experience daytime sleepiness or sleep problems/disturbances interfering with falling or staying asleep. These short sleepers showed significantly larger regional brain volumes than both short sleepers with daytime sleepiness and sleep problems ( n = 1742) and participants sleeping the recommended 7–8 h ( n = 3886). However, both groups of short sleepers showed slightly lower general cognitive function (GCA), 0.16 and 0.19 SDs, respectively. Analyses using accelerometer-estimated sleep duration confirmed the findings, and the associations remained after controlling for body mass index, depression symptoms, income, and education. The results suggest that some people can cope with less sleep without obvious negative associations with brain morphometry and that sleepiness and sleep problems may be more related to brain structural differences than duration. However, the slightly lower performance on tests of general cognitive abilities warrants closer examination in natural settings. SIGNIFICANCE STATEMENT Short habitual sleep is prevalent, with unknown consequences for brain health and cognitive performance. Here, we show that daytime sleepiness and sleep problems are more strongly related to regional brain volumes than sleep duration. However, participants sleeping ≤6 h had slightly lower scores on tests of general cognitive function (GCA). This indicates that sleep need is individual and that sleep duration per se is very weakly if at all related brain health, while daytime sleepiness and sleep problems may show somewhat stronger associations. The association between habitual short sleep and lower scores on tests of general cognitive abilities must be further scrutinized in natural settings.

• Lövden, Martin; Pagin, Amos; Bartres-Faz, David; Boraxbekk, Carl-Johan; Brandmaier, Andreas M. & Demnitz, Naiara [Show all 15 contributors for this article] (2023). No moderating influence of education on the association between changes in hippocampus volume and memory performance in aging. Aging Brain. 4. doi: 10.1016/j.nbas.2023.100082. Full text in Research Archive Show summary

  Contemporary accounts of factors that may modify the risk for age-related neurocognitive disorders highlight education and its contribution to a cognitive reserve. By this view, individuals with higher educational attainment should show weaker associations between changes in brain and cognition than individuals with lower educational attainment. We tested this prediction in longitudinal data on hippocampus volume and episodic memory from 708 middle-aged and older individuals using local structural equation modeling. This technique does not require categorization of years of education and does not constrain the shape of relationships, thereby maximizing the chances of revealing an effect of education on the hippocampus-memory association. The results showed that the data were plausible under the assumption that there was no influence of education on the association between change in episodic memory and change in hippocampus volume. Restricting the sample to individuals with elevated genetic risk for dementia (APOE ε4 carriers) did not change these results. We conclude that the influence of education on changes in episodic memory and hippocampus volume is inconsistent with predictions by the cognitive reserve theory.

• Carver, Rebecca Bruu; Fredheim, Nanna Alida Grit; Mowinckel, Athanasia Monika; Ebmeier, Klaus P.; Friedman, Barbara Bodorkos & Rosness, Tor Atle [Show all 20 contributors for this article] (2022). People's interest in brain health testing: Findings from an international, online cross-sectional survey. Frontiers in Public Health. 10, p. 1–19. doi: 10.3389/fpubh.2022.998302. Full text in Research Archive Show summary

  Brain health entails mental wellbeing and cognitive health in the absence of brain disorders. The past decade has seen an explosion of tests, cognitive and biological, to predict various brain conditions, such as Alzheimer's Disease. In line with these current developments, we investigated people's willingness and reasons to—or not to—take a hypothetical brain health test to learn about risk of developing a brain disease, in a cross-sectional multilanguage online survey. The survey was part of the Global Brain Health Survey, open to the public from 4th June 2019 to 31st August 2020. Respondents were largely recruited via European brain councils and research organizations. 27,590 people responded aged 18 years or older and were predominantly women (71%), middle-aged or older (>40 years; 83%), and highly educated (69%). Responses were analyzed to explore the relationship between demographic variables and responses. Results: We found high public interest in brain health testing: over 91% would definitely or probably take a brain health test and 86% would do so even if it gave information about a disease that cannot be treated or prevented. The main reason for taking a test was the ability to respond if one was found to be at risk of brain disease, such as changing lifestyle, seeking counseling or starting treatment. Higher interest in brain health testing was found in men, respondents with lower education levels and those with poor self-reported cognitive health. Conclusion: High public interest in brain health and brain health testing in certain segments of society, coupled with an increase of commercial tests entering the market, is likely to put pressure on public health systems to inform the public about brain health testing in years to come.

• Nyberg, Lars Erik; Andersson, Micael; Lundquist, Anders; Baaré, William F C; Bartrés-Faz, David & Bertram, Lars [Show all 29 contributors for this article] (2022). Individual differences in brain aging: heterogeneity in cortico-hippocampal but not caudate atrophy rates. Cerebral Cortex. ISSN 1047-3211. 33(9), p. 5075–5081. doi: 10.1093/cercor/bhac400. Full text in Research Archive Show summary

  Abstract It is well documented that some brain regions, such as association cortices, caudate, and hippocampus, are particularly prone to age-related atrophy, but it has been hypothesized that there are individual differences in atrophy profiles. Here, we document heterogeneity in regional-atrophy patterns using latent-profile analysis of 1,482 longitudinal magnetic resonance imaging observations. The results supported a 2-group solution reflecting differences in atrophy rates in cortical regions and hippocampus along with comparable caudate atrophy. The higher-atrophy group had the most marked atrophy in hippocampus and also lower episodic memory, and their normal caudate atrophy rate was accompanied by larger baseline volumes. Our findings support and refine models of heterogeneity in brain aging and suggest distinct mechanisms of atrophy in striatal versus hippocampal-cortical systems.

• Binnewies, Julia; Nawijn, Laura; Brandmaier, Andreas M.; Baaré, William F.C.; Bartres-Faz, David & Drevon, Christian André [Show all 22 contributors for this article] (2022). Associations of depression and regional brain structure across the adult lifespan: Pooled analyses of six population-based and two clinical cohort studies in the European Lifebrain consortium. NeuroImage: Clinical. 36. doi: 10.1016/j.nicl.2022.103180. Full text in Research Archive
• Bråthen, Anne Cecilie Sjøli; Sørensen, Øystein; Lange, Ann-Marie Glasø de; Mowinckel, Athanasia Monika; Fjell, Anders Martin & Walhovd, Kristine B (2022). Cognitive and hippocampal changes weeks and years after memory training. Scientific Reports. 12(1). doi: 10.1038/s41598-022-11636-4. Full text in Research Archive

View all works in NVA

• Fjell, Anders Martin (2026). Søvn. Full text in Research Archive
• Fjell, Anders Martin; Roe, James Michael & Vidal-Piñeiro, Didac (2026). Cortical thickness changes precede high levels of amyloid by at least 7 years-Article Metrics. Nature.com. doi: https:/www.nature.com/articles/s41593-026-02363-4. Full text in Research Archive
• Fjell, Anders Martin (2026). Fagmiljøet splittet om Alzheimer-medisin: Dette mener de om DMPs vurdering. [Internet]. Dagens Medisin. doi: https:/www.dagensmedisin.no/alzheimers-sykdom-dmp-lecanemab/fagmiljoet-splittet-om-alzheimer-medisin-dette-mener-de-om-dmps-vurdering/755550. Full text in Research Archive
• Fjell, Anders Martin & Roe, James Michael (2026). Alzheimers, Alzheimers sykdom | Nytt alzheimer-funn kan avsløre sykdom sju år tidligere. [Internet]. Nettavisen. doi: https:/www.nettavisen.no/nyheter/nytt-alzheimer-funn-kan-avslore-sykdom-sju-ar-tidligere/s/80-95-3641. Full text in Research Archive
• Fjell, Anders Martin (2026). Nytt alzheimer-funn kan avsløre sykdom sju år tidligere. [Internet]. Sykepleien.no. doi: https:/sykepleien.no/2026/08/nytt-alzheimer-funn-kan-avslore-sykdom-sju-ar-tidligere. Full text in Research Archive
• Fjell, Anders Martin & Walhovd, Kristine B (2026). Forskere tar et oppgjør med demens-myter. [Internet]. Forskning.no. doi: https:/www.forskning.no/demens-hjerneforskning-hjernen/forskere-tar-et-oppgjor-med-demens-myter/2677087. Full text in Research Archive
• Fjell, Anders Martin & Roe, James Michael (2026). Kan påvise tegn på Alzheimers sykdom langt tidligere enn antatt. [Internet]. forskning.no. doi: https:/www.forskning.no/alzheimer-hjernen-partner/kan-pavise-tegn-pa-alzheimers-sykdom-langt-tidligere-enn-antatt/2700321. Full text in Research Archive
• Fjell, Anders Martin (2026). Overraskende råd fra hjerneforsker: – Dette er viktigst. doi: https:/www.aftenposten.no/psykisk-helse-og-psykologi/i/2pB3Ly/overraskende-raad-fra-hjerneforsker-dette-er-viktigst. Full text in Research Archive Show summary

  Aftenposten innlegg

• Fjell, Anders Martin (2026). Use of MRI in a precision medicine approach for detection of dementia. Full text in Research Archive
• Fjell, Anders Martin (2026). Punctuated cognitive decline in aging. Full text in Research Archive Show summary

  Ahus sommerseminar

• Fjell, Anders Martin (2026). Hjernen og hukommelse. Hvordan hukommelsen (egentlig) fungerer – og har den noe til felles med KI? Full text in Research Archive
• Fjell, Anders Martin (2026). Hjernen og hukommelse. Hvordan hukommelsen (egentlig) fungerer – og har den noe til felles med KI? Full text in Research Archive
• Fjell, Anders Martin (2026). Individual sleep need, brain health and cognitive function. Full text in Research Archive Show summary

  NordicSleep conference presentation

• Fjell, Anders Martin (2026). A Role for Sleep in Neurodegeneration. Full text in Research Archive Show summary

  Conference presentation, EU MIND

• Garrido, Pablo F.; Walhovd, Kristine B; Krogsrud, Stine Kleppe & Fjell, Anders Martin (2026). Hippocampal volume measured from early childhood to adolescence predicts virtual navigation up to 16 years later. doi: https:/www.inavsymposium.com/wp-content/uploads/2026/07/iNAV2026_Poster_Abstracts_V2.pdf. Full text in Research Archive Show summary

  Poster presentation

• Walhovd, Kristine B; Sneve, Markus Handal; Garrido, Pablo F.; Kransberg, Jonas Moe & Fjell, Anders Martin (2026). Navigation training alters twin cortical similarity at the gray-white matter boundary. doi: https:/www.humanbrainmapping.org/aperture-neuro/. Full text in Research Archive Show summary

  Talk at OHBM 2026

• Garrido, Pablo F.; Øverbye, Knut Eiliv Ødegård; Kransberg, Jonas Moe; Barhaug, Eline; Eggset, Marie & Iversen, Johanne Bjørndal [Show all 8 contributors for this article] (2026). Emerging navigation behaviors in a VR city: unsupervised strategy detection in an adult twin cohort. Full text in Research Archive
• Stavestrand, Silje Haukenes; Djup, Heidi Wittrup; Fjell, Anders Martin; Hyldmo, Ingrid & Sirevåg, Kristine (2026). Til he***te med eldrebølgen. doi: https:/www.youtube.com/watch?v=r5FqHktfKl8&t=2405s. Full text in Research Archive Show summary

  I en samfunnsdebatt der eldre mennesker omtales som økonomiske belastninger, omsorgsutfordringer eller som en bølge som må håndteres, blir formidling av kunnskapsbaserte perspektiver en sentral oppgave for psykologstanden. Aldringsfeltet preges av stereotype forestillinger, unyansert språkbruk, begrenset rekruttering og manglende satsing. Men er bildet dekkende?

• Fjell, Anders Martin (2025). Why do people with more education tend to have better memory in older age - A population neuroscience approach. doi: https:/share-berlin.eu/en/events/siss-november/. Full text in Research Archive Show summary

  Webinar presentation

• Fjell, Anders Martin (2025). Differences in cognitive function at 18y of age explain the association between low education and early dementia risk. Full text in Research Archive
• Walhovd, Kristine B; Kransberg, Jonas Moe; Krogsrud, Stine Kleppe & Fjell, Anders Martin (2025). Hippocampal Volume in Childhood Predicts Navigation Performance 6–16 Years Later. Full text in Research Archive Show summary

  Poster presentation at Flux Congress

• Fjell, Anders Martin (2025). Does education help build a cognitive reserve to ward off dementia? [Internet]. The New Scientist. doi: https:/www.lcbc.uio.no/english/news/does-education-help-build-a-cognitive-reserve-to-ward-off-dementia_-_-new-scientist.pdf. Full text in Research Archive
• Fjell, Anders Martin (2025). Å bli foreldre ser ut til å beskytte hjernen mot aldring – hos både menn og kvinner. [Internet]. forskning.no. doi: https:/www.forskning.no/familie-foreldre-hjernen/a-bli-foreldre-ser-ut-til-a-beskytte-hjernen-mot-aldring-hos-bade-menn-og-kvinner/2479025. Full text in Research Archive
• Fjell, Anders Martin (2025). Need a good night's sleep? Try changing how you think about it. [Internet]. BBC. doi: https:/www.bbc.com/future/article/20241014-need-a-good-nights-sleep-trying-changing-how-you-think-about-it. Full text in Research Archive
• Fjell, Anders Martin (2025). Hvor mye søvn trenger hjernen vår? Full text in Research Archive
• Fjell, Anders Martin (2025). Memory decline in aging – a population neuroscience approach. Full text in Research Archive
• Fjell, Anders Martin (2025). Population neuroscience - sample case of education and brain aging. Full text in Research Archive
• Fjell, Anders Martin (2025). Hukommelse og utdanning: Gjør mer skolegang at vi husker bedre når vi blir eldre? doi: https:/www.uio.no/om/aktuelt/universitetsplassen/domus-bibliotheca/arrangementer/2025/kognisjon-i-endring. Full text in Research Archive
• Grødem, Edvard Olaf Sætersdal; Vidal-Piñeiro, Didac; Sørensen, Øystein; Garrido, Pablo F.; Nyberg, Lars Erik & Walhovd, Kristine B [Show all 8 contributors for this article] (2025). Distinguishing Lifelong Individual Differences from Divergent Aging Trajectories of Adult Brain Volumes. bioRxiv (preprint article). 2025.05.26.655710. doi: 10.1101/2025.05.26.655710. Full text in Research Archive
• Roe, James Michael; Grydeland, Håkon; Slivka, Maksim; Sørensen, Øystein; Grødem, Edvard Olaf Sætersdal & Walhovd, Kristine B [Show all 8 contributors for this article] (2025). Cortical thickness changes precede high levels of amyloid by at least seven years. bioRxiv (preprint article). doi: 10.1101/2025.08.14.670398. Full text in Research Archive
• Fjell, Anders Martin (2024). Hvilken rolle spiller hjerneavbildning (med fokus på MR) i nevropsykologi. Full text in Research Archive
• Fjell, Anders Martin (2024). Kognitive endringer gjennom livsløpet. doi: https:/www.hjerneradet.no/hjernehelsekonferansen2024-4/. Full text in Research Archive
• Strømstad, Marie Lorentsen; Fjell, Anders Martin; Walhovd, Kristine B; Vidal-Piñeiro, Didac & Sørensen, Øystein (2024). Longitudinal association between structural brain change and episodic memory change. Full text in Research Archive
• Padrela, Beatriz; Mahroo, Amnah; Tee, Mervin; Sneve, Markus Handal; Moyaert, Paulien & Geier, Oliver [Show all 43 contributors for this article] (2024). Developing blood-brain barrier arterial spin labelling as a non-invasive early biomarker of Alzheimer's disease (DEBBIE-AD): a prospective observational multicohort study protocol. BMJ Open. 14(3). doi: 10.1136/bmjopen-2023-081635. Full text in Research Archive Show summary

  Introduction Loss of blood-brain barrier (BBB) integrity is hypothesised to be one of the earliest microvascular signs of Alzheimer’s disease (AD). Existing BBB integrity imaging methods involve contrast agents or ionising radiation, and pose limitations in terms of cost and logistics. Arterial spin labelling (ASL) perfusion MRI has been recently adapted to map the BBB permeability non-invasively. The DEveloping BBB-ASL as a non-Invasive Early biomarker (DEBBIE) consortium aims to develop this modified ASL-MRI technique for patient-specific and robust BBB permeability assessments. This article outlines the study design of the DEBBIE cohorts focused on investigating the potential of BBB-ASL as an early biomarker for AD (DEBBIE-AD). Methods and analysis DEBBIE-AD consists of a multicohort study enrolling participants with subjective cognitive decline, mild cognitive impairment and AD, as well as age-matched healthy controls, from 13 cohorts. The precision and accuracy of BBB-ASL will be evaluated in healthy participants. The clinical value of BBB-ASL will be evaluated by comparing results with both established and novel AD biomarkers. The DEBBIE-AD study aims to provide evidence of the ability of BBB-ASL to measure BBB permeability and demonstrate its utility in AD and AD-related pathologies. Ethics and dissemination Ethics approval was obtained for 10 cohorts, and is pending for 3 cohorts. The results of the main trial and each of the secondary endpoints will be submitted for publication in a peer-reviewed journal.

• Fjell, Anders Martin (2024). Kan man sove seg til Alzheimer? Full text in Research Archive
• Fjell, Anders Martin (2024). Brain and Cognition in aging - Heterogenic trajctories? Full text in Research Archive
• Fjell, Anders Martin (2024). Education and memory. Full text in Research Archive
• Fjell, Anders Martin (2024). A critical view on «aquired» risk factors for dementia – focus on low education. Full text in Research Archive
• Fjell, Anders Martin (2024). Hukommelse, falske minner, déjà vu og hjernetrim. [Internet]. Ganske aktuelt med Kenneth Bergh" podcast. Full text in Research Archive
• Fjell, Anders Martin (2024). Why you shouldn’t worry if you only get six hours sleep. [Internet]. inews. Full text in Research Archive
• Fjell, Anders Martin & Walhovd, Kristine B (2024). Imaging the timing of influences on brain and cognition across the lifespan. Full text in Research Archive
• Fjell, Anders Martin (2024). Successful episodic memory function in aging. Full text in Research Archive
• Fjell, Anders Martin (2023). Bruk av hjerneavbildning i kognitiv nevrovitenskap. Full text in Research Archive
• Fjell, Anders Martin (2023). Hvor mye søvn trenger hjernen vår? Full text in Research Archive
• Fjell, Anders Martin (2023). Not getting enough sleep may be less harmful to the brain than some have feared. [Internet]. The New Scientist. Full text in Research Archive
• Fjell, Anders Martin (2023). Tett på Kristine Beate Walhovd og Anders Fjell: Forsker på hjernen vår for å forstå hvorfor vi utvikler oss så forskjellig. [Internet]. UiO Podcast. Full text in Research Archive
• Fjell, Anders Martin (2022). The role of sleep in brain health and cognitive function. Full text in Research Archive
• Fjell, Anders Martin (2022). Maskinlæringsbasert analyse av MRI for tidligere oppdagelse av Alzheimers Sykdom. Full text in Research Archive
• Fjell, Anders Martin (2022). Nyvinnende bruk av kvantitativ MRI for tidligere oppdagelse av Alzheimers Sykdom. Full text in Research Archive
• Fjell, Anders Martin (2022). Søvn og hjernehelse gjennom livet. Full text in Research Archive
• Fjell, Anders Martin (2022). In search of factors influencing or not influencing brain and cognition - Results from the Lifebrain 2020 project and beyond. Full text in Research Archive
• Grødem, Edvard Olaf Sætersdal; Fjell, Anders Martin; Bjørnerud, Atle; MacIntosh, Bradley & Edin, Nina Frederike Jeppesen (2025). Characterizing Brain MRI with Machine Learning Methods with Applications to Alzheimer’s Disease. Universitetet i Oslo. Full text in Research Archive Show summary

  The human brain undergoes lifelong structural changes that reflect both normal aging and pathological processes. Alzheimer’s disease (AD) is neurodegenerative disorder that causes pronounced structural changes in the brain in the form of atrophy. In AD, patients’ cognitive function is permanently reduced, and treatment options are limited. Magnetic resonance imaging (MRI) makes it possible to observe these structural changes in vivo. Over the past twenty years, large open imaging databases (e.g., the Alzheimer’s Disease Neuroimaging Initiative (ADNI) and UK Biobank) have enabled studies involving tens of thousands of participants. At the same time, there have been major advances in machine-learning methods, for example in deep learning, Bayesian statistics and image processing. Together, large databases and new machine-learning techniques open up deeper insights into the brain’s evolving anatomy. Nevertheless, challenges remain. There is considerable inter-individual anatomical differences, and distinguishing natural variation from pathology can be difficult. The MRI data themselves present additional hurdles: the mages are large three-dimensional scans that must be processed to obtain measurable quantities such as regional volume and cortical thickness. Although the imaging databases are extensive, scans often originate from many different scanners, leading to contrast differences that complicate direct comparisons. In longitudinal studies, the morphological changes of interest are often smaller than the measurement noise. Consequently, new methods are needed to analyze changes in brain MRI reliably. In this thesis, the aim is to develop and improve machine-learning methods for analyzing brain MRI. These methods are intended to quantify changes in brain structures, to characterize the brain’s Natural development across the lifespan and to diagnose AD. The work comprises three papers. In Paper I we use deep learning to diagnose Alzheimer’s disease from brain MRI. We investigate how the architecture of the deep convolutional network influences the classification outcome. MRI scans of individuals with AD and healthy controls from ADNI serve as material. We find that more complex and deeper architectures such as EfficientNet do not outperform simpler and shallower architectures such as the Simple Fully Convolutional Network (SFCN). Further analyses show that SFCN can be scaled down to very small sizes while still providing strong results. These findings indicate that straightforward preprocessing combined with simple convolutional networks yields classification performance comparable to the more elaborate methods reported in the literature. In Paper II we study volume changes of various brain structures across the lifespan. We aim to determine when there are individual changes in the brain due to normal aging and to what extent these can be estimated at the individual level. A large dataset of longitudinal brain MRI collected from 14 studies is employed. We model the volume of the brain structures as a stochastic dynamical system and fit the model to the data using a Markov chain Monte Carlo approach. The results show that the brain changes throughout life, but up to the age of 50 there are only small individual differences in the rate of change. After 50 years we observe greater individual variation. From the model we calculate the explained variance from the structure volume at age 18 to the volume later in life, finding that up to 60 years almost all variance is explained by the young-adult volume. The lateral ventricles stand out: here, individual variation in change persists throughout life. We further estimate how accurately individual change can be inferred for single subjects. For individuals under 50 years there is virtually no correlation between an estimated change and the actual individualchange; after 50 years this correlation increases with age. Increasing the interval between volume measurements effectively increases this correlation, whereas adding more measurements within a given interval has a smaller effect. Paper III examines medical image-registration algorithms, in which a deformation field that aligns two images is estimated so that anatomically identical regions overlap. This can be used both to compare images across individuals and to study anatomical changes over time. Registration is often performed by minimising the image-similarity loss Local Normalised Cross-Correlation (LNCC). We show that using LNCC can lead to erroneous deformation estimates in homogeneous regions where noise dominates the signal. Two new variants are proposed: Regularized-LNCC (R-LNCC) and Weighted-LNCC (W-LNCC). We use real MRI from a wide range of scanners and generate synthetic deformations to test how well the similarity metrics recover them. LNCC produces incorrect deformation estimates in low-variance regions, whereas R-LNCC and W-LNCC resolve this issue. We also find that R-LNCC generally yields significantly better deformation estimates than LNCC, even in more heterogeneous regions. Together, Papers I, II and III constitute a framework for studying changes in the brain. Our aim is that these tools will be utilized to better understand Alzheimer’s disease and promote healthy aging.

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