From attentional fluctuations to intentional fluctuations? Monitoring behavior and intraindividual variability in time-based prospective memory.

In sharp contrast to event-based prospective memory (PM), dynamics of (re)allocation of attention between the ongoing and PM tasks have been much less investigated in time-based PM tasks. We propose an in-depth examination of attention allocation in a time-based PM task by jointly analyzing multiple indicators of time-monitoring behavior, net and time-structured intraindividual variability (IIV) in ongoing-task reaction times (OT RTs), and task performance. Results from dynamic structural equation modeling in a lifespan sample of 198 adults (19-86 years) revealed that larger fluctuations in OT RTs (net IIV) predicted poorer OT performance, but fostered a more efficient pattern of time-monitoring behavior (i.e., checking a clock more frequently and strategically, and slowing OT RTs during the PM response window) that, in turn, enhanced PM. Conversely, greater inertia in OT RTs (time-structured IIV) led to fewer clock-checks and poorer PM performance. Focusing attention on time monitoring to enhance PM performance did not detrimentally affect OT accuracy. Instead, participants showed a speed-accuracy tradeoff to optimize both OT and PM accuracies by slowing their OT RTs during the PM response window. This study therefore shows that two concomitant aspects of IIV (net and time-structured IIV) not only predicted time-monitoring behavior, but also OT and PM accuracies differentially, hence advocating for the necessity to consider both aspects of IIV and time monitoring together to better understand attention allocation policies in time-based PM tasks. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Linear mixed models and latent growth curve models for group comparison studies contaminated by outliers.

The linear mixed model (LMM) and latent growth model (LGM) are frequently applied to within-subject two-group comparison studies to investigate group differences in the time effect, supposedly due to differential group treatments. Yet, research about LMM and LGM in the presence of outliers (defined as observations with a very low probability of occurrence if assumed from a given distribution) is scarce. Moreover, when such research exists, it focuses on estimation properties (bias and efficiency), neglecting inferential characteristics (e.g., power and type-I error). We study power and type-I error rates of Wald-type and bootstrap confidence intervals (CIs), as well as coverage and length of CIs and mean absolute error (MAE) of estimates, associated with classical and robust estimations of LMM and LGM, applied to a within-subject two-group comparison design. We conduct a Monte Carlo simulation experiment to compare CIs and MAEs under different conditions: data (a) without contamination, (b) contaminated by within-subject outliers, (c) contaminated by between-subject outliers, and (d) both contaminated by within- and between-subject outliers. Results show that without contamination, methods perform similarly, except CIs based on S, a robust LMM estimator, which are slightly less close to nominal values in their coverage. However, in the presence of both within- and between-subject outliers, CIs based on robust estimators, especially S, performed better than those of classical methods. In particular, the percentile CI with the wild bootstrap applied to the robust LMM estimators outperformed all other methods, especially with between-subject outliers, when we found the classical Wald-type CI based on the t statistic with Satterthwaite approximation for LMM to be highly misleading. We provide R code to compute all methods presented here. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

On some challenges of psychological research in late adulthood and aging.

The World population is aging and, consequently, understanding late adulthood and aging processes is a major scientific priority. Research in this segment of the life is particularly challenging: the lifespan approach, necessary for thorough aging investigations, implies theoretical multidisciplinary and methodological multivariate perspectives; variability during aging is particularly high compared to previous life phases; study designs must account for specific predicaments (such as confound between age, cohort, and time of measurement; selective study participation and attrition; assumed age-invariance of measurements; retest effects). Furthermore, promising methods for data analysis develop on a daily basis, requiring continuous technical training. I will discuss some of these challenges, summarize extant potential solutions, and touch on some ethical and broader social responsibility issues.

No phenotypic or genotypic evidence for a link between sleep duration and brain atrophy.

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.

Between-person and within-person associations among sensory functioning and attitude toward own aging in old age: Evidence for mutual relations.

Late-life hearing loss and vision loss might prompt more negative attitudes toward one's own aging because older adults may interpret impaired sensory functioning as a sign of aging. At the same time, more positive attitudes toward own aging might, via various mechanisms, be associated with better sensory functioning. We investigated how objective hearing and vision are associated with attitude toward own aging (ATOA) over time. Our sample comprised 497 participants from the Berlin Aging Study (mean baseline age: 85.15 years, SD = 8.58 years) who provided up to six observations over an average time span of 3.73 years (range 0-15 years). We computed longitudinal multilevel regression models, specifying vision, hearing, and age as within-person and between-person predictors of ATOA, and ATOA and age as between- and within-person predictors of vision and hearing. Covariates were sex, socioeconomic status, suspected dementia, chronic physical diseases, and depression. Significant within-person age effects indicated that vision and hearing declined over time, and ATOA became less favorable over time. At the between-person level, we found that participants with a more favorable ATOA exhibited better hearing, but not better vision, at baseline. Between-person associations of vision and hearing with ATOA were not significant. At the within-person level, there was only one significant effect across all models: On measurement occasions when individuals' vision was better, they also reported more favorable ATOA. This association was stronger among older individuals. Improving prevention and treatment of vision loss could thus help older adults to maintain positive views on their own aging. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

No moderating influence of education on the association between changes in hippocampus volume and memory performance in aging.

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.

The Current and Retrospective Cognitive Reserve (2CR) survey and its relationship with cognitive and mood measures.

Cognitive Reserve (CR) is often assessed with surveys spanning demographic, lifestyle, and socio-behavioral variables. The role of both past and current life experiences on CR has, however, rarely been examined. We developed the Current and Retrospective Cognitive Reserve (2CR) survey to assess classical CR proxies (socio-economic status, engagement in leisure and social activities) and other dimensions of potential importance (family engagement, religious/spiritual activity) both currently (CRc; in later adulthood) and retrospectively (CRr; as recalled from younger adulthood). We administered the 2CR, measures of general cognitive functioning, working memory (WM), crystallized-vocabulary- and fluid-reasoning-intelligence, and depressive symptoms (DS) to 235 community-dwelling Italian adults (ages 55-90 years). We used exploratory and confirmatory factor analyses to examine the 2CR latent structure, and we estimated correlations of its dimensions with cognitive abilities and DS. Analyses confirmed a three-level factor structure with two global CR factors (CRc and CRr) at the top level, dimensional CR factors (socio-economic status, family engagement, leisure activity, social engagement, and religious/spiritual activity) at mid-level and observed items at the lowest level. Item-factor representations partially differed across CRc and CRr. Both CRc and CRr were positively correlated with measures of intelligence, WM and DS, but associations of measures of intelligence were stronger for CRr, whereas associations of WM and DS were slightly stronger for CRc. The 2CR can be considered a reliable survey for assessing CR proxies within a multidimensional, "life stage-dependent" framework insofar as CRc are CRr closely related but also differently associated with intelligence, WM, and DS.

Is Short Sleep Bad for the Brain? Brain Structure and Cognitive Function in Short Sleepers.

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 <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.

Stakeholder engagement in European brain research: Experiences of the Lifebrain consortium.

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.

Today's Older Adults Are Cognitively Fitter Than Older Adults Were 20 Years Ago, but When and How They Decline Is No Different Than in the Past.

History-graded increases in older adults' levels of cognitive performance are well documented, but little is known about historical shifts in within-person change: cognitive decline and onset of decline. We combined harmonized perceptual-motor speed data from independent samples recruited in 1990 and 2010 to obtain 2,008 age-matched longitudinal observations (M = 78 years, 50% women) from 228 participants in the Berlin Aging Study (BASE) and 583 participants in the Berlin Aging Study II (BASE-II). We used nonlinear growth models that orthogonalized within- and between-person age effects and controlled for retest effects. At age 78, the later-born BASE-II cohort substantially outperformed the earlier-born BASE cohort (d = 1.20; 25 years of age difference). Age trajectories, however, were parallel, and there was no evidence of cohort differences in the amount or rate of decline and the onset of decline. Cognitive functioning has shifted to higher levels, but cognitive decline in old age appears to proceed similarly as it did two decades ago.

Age-Related Hearing Loss, Cognitive Performance, and Metabolic Risk in Healthy Adults: A Seven-Year Longitudinal Study.

OBJECTIVES: Sensorineural hearing loss (presbycusis) affects up to half of the adults, is associated with cognitive decline. Whether this association reflects the cause, the consequence, or parallel processes driven by other factors remains unclear. Both presbycusis and cognition are linked to elevated metabolic risk, which in turn raises with age. METHOD: In a multioccasion longitudinal design, we used latent change score models with strong factorial invariance to assess the change in pure-tone threshold auditory function, fluid intelligence, metabolic risk, variability therein, and the dynamic relationships among the 3 domains. We examined, up to 4 times over more than 7 years, a sample of relatively healthy 687 adults (aged 18.17-83.25 years). RESULTS: We found that levels of auditory and cognitive functioning at time t-1 influence each other's subsequent change between times t-1 and t, even when controlling for the reciprocal effects of metabolic risk on both. Thus, auditory and cognitive functioning do not only decline in parallel in healthy adults, but also affect each other's trajectories. To the best of our knowledge, this is the first long-term study with such evidence. DISCUSSION: Our results are in accord with extant hypotheses about auditory-cognitive associations in old age (e.g., social isolation, cognitive load, increased inflammation, reduced gene expression, and other microvascular or neuropathological factors). They also echo previous reports underscoring the need for improving access to hearing aids and other rehabilitative services aimed at reducing hearing loss. If applied early in the aging process, such interventions may mitigate cognitive decline.

Individual differences in brain aging: heterogeneity in cortico-hippocampal but not caudate atrophy rates.

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.

People's interest in brain health testing: Findings from an international, online cross-sectional survey.

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.

Residential trajectories across the life course and their association with cognitive functioning in later life.

Previous work has found that later life urban-rural differences in cognitive health can be largely explained by indicators of cognitive reserve such as education or occupation. However, previous research concentrated on residence in limited, specific, periods. This study offers a detailed investigation on the association between urban (vs. rural) residence from birth, and cognitive functioning in older age. Using data from the Survey of Health Ageing and Retirement in Europe we created residential trajectories from birth to survey enrolment with a combination of sequence and cluster analysis. Using mixed-effects models, we investigated the association between residential trajectories in early, mid, and later life and three cognitive functioning outcomes: immediate recall, delayed recall, and verbal fluency. In a sample of 38,165 participants, we found that, even after accounting for differences related to education and occupation, rural (vs. urban) residence in early life remained associated with poorer cognitive performance later in life. This suggests that growing up in rural regions leads to a long-term disadvantage in cognitive functioning. Thus, public health policies should consider that urban-rural inequalities in early life may have long-lasting associations with inequalities in cognitive health in old and very old age.

Brain aging differs with cognitive ability regardless of education.

Higher general cognitive ability (GCA) is associated with lower risk of neurodegenerative disorders, but neural mechanisms are unknown. GCA could be associated with more cortical tissue, from young age, i.e. brain reserve, or less cortical atrophy in adulthood, i.e. brain maintenance. Controlling for education, we investigated the relative association of GCA with reserve and maintenance of cortical volume, -area and -thickness through the adult lifespan, using multiple longitudinal cognitively healthy brain imaging cohorts (n = 3327, 7002 MRI scans, baseline age 20-88 years, followed-up for up to 11 years). There were widespread positive relationships between GCA and cortical characteristics (level-level associations). In select regions, higher baseline GCA was associated with less atrophy over time (level-change associations). Relationships remained when controlling for polygenic scores for both GCA and education. Our findings suggest that higher GCA is associated with cortical volumes by both brain reserve and -maintenance mechanisms through the adult lifespan.

Frequency and strategicness of clock-checking explain detrimental age effects in time-based prospective memory.

Previous studies report that monitoring the passing of time by checking a clock either frequently or strategically (immediately before a target time) improves the likelihood of remembering to perform a planned intention at a specific time (i.e., time-based prospective memory [TBPM]). Critically, strategicness of clock-checking is usually measured as the number of clock-checks during the last time interval before the target time-an operationalization where strategicness actually intertwines with absolute frequency of clock-checking and may not properly account for age effects in TBPM performance. To disentangle the respective contribution of frequent versus strategic clock-checking to the age-related decrease in TBPM performance, we propose a new, more fine-grained indicator of strategicness (i.e., relative clock-checking), which accounts for interindividual differences in the total frequency of clock-checking (i.e., absolute clock-checking). In this study, 223 participants from an adult lifespan sample (age range = 19-86, M = 45.61, SD = 17.24; 70% women) had to remember to push the ENTER key every 60 s while performing a two-back picture decision task. Together, relative and absolute clock-checking fully mediated the negative age effect on TBPM and explained 53.6% of the variance of TBPM performance. Complementary analyses revealed that both indicators were needed to fully mediate the effect of age on TBPM, but that strategic (i.e., relative) clock-checking was a stronger predictor of TBPM performance than absolute clock-checking. These results stress the importance of considering both aspects of clock-checking to investigate time monitoring in laboratory TBPM tasks and age effects therein, and provide avenues of intervention for improving older adults' TBPM. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Psychological distress and well-being among students of health disciplines in Geneva, Switzerland: The importance of academic satisfaction in the context of academic year-end and COVID-19 stress on their learning experience.

INTRODUCTION: University students' psychological health is linked to their academic satisfaction. This study aimed to investigate students' psychological health and academic satisfaction in the context of COVID-19 and academic year-end stress. MATERIALS AND METHODS: Standardized self-filled scales for anxiety, depression, stress, psychological well-being, academic satisfaction (subjective assessment of students' quality of life in their educational setting), and an ad-hoc scale for stress on the learning experience due to COVID-19 were used in this cross-sectional study. Participants were first- to third-year students of eight different health-related tracks in Geneva, Switzerland. Descriptive statistics and hierarchical regression analyses were applied. RESULTS: In June 2020, out of 2835 invited students, 433 (15%) completed the survey. Academic satisfaction was a stronger mental health predictor than COVID-19 stress on the learning experience, which mainly predicted stress and anxiety. Lower academic satisfaction scores were significantly associated with stress (ß = -0.53, p < 0.001), depression (ß = -0.26, p < 0.001), anxiety (ß = -0.20, p < 0.001), while higher scores with psychological well-being (ß = 0.48, p < 0.001). Identifying as female was strongly associated with anxiety and stress but not with depression or psychological well-being. Lower age was associated with stress only. The nature of the academic training had a lesser impact on mental health and the academic year had no impact. CONCLUSIONS: Academic satisfaction plays a more substantial role than COVID-19 stress on the learning experience in predicting students' overall mental health status. Training institutions should address the underlying factors that can enhance students' academic satisfaction, especially during the COVID-19 period, in addition to ensuring that they have a continuous and adequate learning experience, as well as access to psychosocial services that help them cope with mental distress and enhance their psychological well-being.

Public perceptions of brain health: an international, online cross-sectional survey.

OBJECTIVES: To investigate public perspectives on brain health. DESIGN: Cross-sectional multilanguage online survey. SETTING: Lifebrain posted the survey on its website and social media and shared it with stakeholders. The survey was open from 4 June 2019 to 31 August 2020. PARTICIPANTS: n=27 590 aged ≥18 years from 81 countries in five continents completed the survey. The respondents were predominantly women (71%), middle aged (41-60 years; 37%) or above (>60 years; 46%), highly educated (69%) and resided in Europe (98%). MAIN OUTCOME MEASURES: Respondents' views were assessed regarding factors that may influence brain health, life periods considered important to look after the brain and diseases and disorders associated with the brain. We run exploratory linear models at a 99% level of significance to assess correlates of the outcome variables, adjusting for likely confounders in a targeted fashion. RESULTS: Of all significant effects, the respondents recognised the impact of lifestyle factors on brain health but had relatively less awareness of the role socioeconomic factors might play. Most respondents rated all life periods as important for the brain (95%-96%), although the prenatal period was ranked significantly lower (84%). Equally, women and highly educated respondents more often rated factors and life periods to be important for brain health. Ninety-nine per cent of respondents associated Alzheimer's disease and dementia with the brain. The respondents made a connection between mental health and the brain, and mental disorders such as schizophrenia and depression were significantly more often considered to be associated with the brain than neurological disorders such as stroke and Parkinson's disease. Few respondents (<32%) associated cancer, hypertension, diabetes and arthritis with the brain. CONCLUSIONS: Differences in perceptions of brain health were noted among specific segments of the population. Policies providing information about brain-friendly health behaviours and targeting people less likely to have relevant experience may be needed.

How Welfare Regimes Moderate the Associations Between Cognitive Aging, Education, and Occupation.

OBJECTIVES: Previous studies have shown the importance of individual markers of cognitive reserve, such as education and occupation, for cognitive health in old age. However, there has been only little investigation so far on how this relationship varies across contexts. METHODS: We analyzed data from the Survey of Health, Ageing, and Retirement in Europe, using second-order latent growth models, to assess the moderating role of welfare regimes on the relationship between education and occupation skill level in explaining overall cognitive functioning and decline in old age. Our sample includes 13 European countries using data from 5 regular waves of the survey (2004-2007 and 2011-2015) and 2 retrospective ones (2008-2009 and 2017). Cognitive functioning was modeled as a latent variable measured by immediate and delayed recall, verbal fluency, and numeracy. RESULTS: 74,193 participants were included from the survey. Our analysis showed that the association of education with cognition was weaker overall in Scandinavian countries, but stronger in Southern European countries, relative to Bismarckian ones. However, educational differences in the decline of cognition were more pronounced only in Scandinavian compared to Bismarckian countries. Additionally, higher-skilled occupations in Scandinavian countries had better overall functioning compared to the same occupations in Bismarckian countries, but there was no difference in the decline in cognitive functioning. DISCUSSION: Our findings indicate that the associations of cognitive functioning and its decline with individuals' cognitive reserve markers (education and occupational skill level) vary according to welfare regimes, showing the importance of contextual factors in cognitive aging processes.

Education and Income Show Heterogeneous Relationships to Lifespan Brain and Cognitive Differences Across European and US Cohorts.

Higher socio-economic status (SES) has been proposed to have facilitating and protective effects on brain and cognition. We ask whether relationships between SES, brain volumes and cognitive ability differ across cohorts, by age and national origin. European and US cohorts covering the lifespan were studied (4-97 years, N = 500 000; 54 000 w/brain imaging). There was substantial heterogeneity across cohorts for all associations. Education was positively related to intracranial (ICV) and total gray matter (GM) volume. Income was related to ICV, but not GM. We did not observe reliable differences in associations as a function of age. SES was more strongly related to brain and cognition in US than European cohorts. Sample representativity varies, and this study cannot identify mechanisms underlying differences in associations across cohorts. Differences in neuroanatomical volumes partially explained SES-cognition relationships. SES was more strongly related to ICV than to GM, implying that SES-cognition relations in adulthood are less likely grounded in neuroprotective effects on GM volume in aging. The relatively stronger SES-ICV associations rather are compatible with SES-brain volume relationships being established early in life, as ICV stabilizes in childhood. The findings underscore that SES has no uniform association with, or impact on, brain and cognition.