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.

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.

Educational attainment does not influence brain aging.

Education has been related to various advantageous lifetime outcomes. Here, using longitudinal structural MRI data (4,422 observations), we tested the influential hypothesis that higher education translates into slower rates of brain aging. Cross-sectionally, education was modestly associated with regional cortical volume. However, despite marked mean atrophy in the cortex and hippocampus, education did not influence rates of change. The results were replicated across two independent samples. Our findings challenge the view that higher education slows brain aging.

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.

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.

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.

Poor Self-Reported Sleep is Related to Regional Cortical Thinning in Aging but not Memory Decline-Results From the Lifebrain Consortium.

We examined whether sleep quality and quantity are associated with cortical and memory changes in cognitively healthy participants across the adult lifespan. Associations between self-reported sleep parameters (Pittsburgh Sleep Quality Index, PSQI) and longitudinal cortical change were tested using five samples from the Lifebrain consortium (n = 2205, 4363 MRIs, 18-92 years). In additional analyses, we tested coherence with cell-specific gene expression maps from the Allen Human Brain Atlas, and relations to changes in memory performance. "PSQI # 1 Subjective sleep quality" and "PSQI #5 Sleep disturbances" were related to thinning of the right lateral temporal cortex, with lower quality and more disturbances being associated with faster thinning. The association with "PSQI #5 Sleep disturbances" emerged after 60 years, especially in regions with high expression of genes related to oligodendrocytes and S1 pyramidal neurons. None of the sleep scales were related to a longitudinal change in episodic memory function, suggesting that sleep-related cortical changes were independent of cognitive decline. The relationship to cortical brain change suggests that self-reported sleep parameters are relevant in lifespan studies, but small effect sizes indicate that self-reported sleep is not a good biomarker of general cortical degeneration in healthy older adults.

Meta-analysis of generalized additive models in neuroimaging studies.

Analyzing data from multiple neuroimaging studies has great potential in terms of increasing statistical power, enabling detection of effects of smaller magnitude than would be possible when analyzing each study separately and also allowing to systematically investigate between-study differences. Restrictions due to privacy or proprietary data as well as more practical concerns can make it hard to share neuroimaging datasets, such that analyzing all data in a common location might be impractical or impossible. Meta-analytic methods provide a way to overcome this issue, by combining aggregated quantities like model parameters or risk ratios. Most meta-analytic tools focus on parametric statistical models, and methods for meta-analyzing semi-parametric models like generalized additive models have not been well developed. Parametric models are often not appropriate in neuroimaging, where for instance age-brain relationships may take forms that are difficult to accurately describe using such models. In this paper we introduce meta-GAM, a method for meta-analysis of generalized additive models which does not require individual participant data, and hence is suitable for increasing statistical power while upholding privacy and other regulatory concerns. We extend previous works by enabling the analysis of multiple model terms as well as multivariate smooth functions. In addition, we show how meta-analytic p-values can be computed for smooth terms. The proposed methods are shown to perform well in simulation experiments, and are demonstrated in a real data analysis on hippocampal volume and self-reported sleep quality data from the Lifebrain consortium. We argue that application of meta-GAM is especially beneficial in lifespan neuroscience and imaging genetics. The methods are implemented in an accompanying R package metagam, which is also demonstrated.

A Mixed-Method Study on Strategies in Everyday Personal Goals among Community-Dwelling Older Adults.

INTRODUCTION: Although it is well known that preference for selection, optimization, and compensation (SOC) strategies is associated with indicators of successful aging and well-being, very little is known about what predicts the use of SOC as goal management strategies in the daily lives of older adults. The present study investigates predictors of self-reported use of SOC strategies in community-dwelling adults. We expected selection and especially compensation to be higher in individuals with worse subjective health and cognitive performance. On the contrary, given that optimization is an anticipatory strategy to increase goal-relevant means in the absence of resource losses, we did not expect optimization to be related to either health or cognition. METHODS: We performed hierarchical regression to predict use of SOC strategies to achieve everyday personal goals (assessed qualitatively via semi-structured interviews exploring participants' personal goals) from subjective health and objective cognitive performance, controlling for age, apathy, and depression. RESULTS: Poorer self-rated health and worse cognitive performance positively predicted compensation as a goal management strategy (R2 = 20%), whereas self-rated health just failed to significantly predict selection rates. None of the variables of interest predicted optimization. DISCUSSION/CONCLUSION: Whereas previous research suggests associations between reduced resources and decreased absolute frequency of compensation use, the present study found that poorer cognitive status and perceived health are both linked to increased reliance on compensation in order to preserve well-being. In line with their anticipatory nature, the use of optimization strategies was independent from health and cognitive resources in our sample. We discuss the absence of conclusive effects regarding selection in this study in light of the distinction between elective and loss-based selection.

Longitudinal Relationships Between Reflective Functioning, Empathy, and Externalizing Behaviors During Adolescence and Young Adulthood.

Reflective functioning (RF) refers to the understanding of one's own and others' behaviors in terms of mental states, whereas empathy entails the abilities to understand (cognitive empathy) and to share (affective empathy) the emotions of others. Low RF and low empathy have been previously related to externalizing behaviors, such as aggression and rule breaking. However, few longitudinal studies have simultaneously examined the relationships between these variables during adolescence. The aim of the present study is to investigate the longitudinal effects of both RF and empathy on potential changes in externalizing behaviors over time, in a group of 103 adolescents and young adults from the general population assessed repeatedly up to four times. We conducted multilevel analysis in order to examine the effects of RF and empathy on the initial levels and the trajectories of externalizing behaviors over time, while accounting for other variables previously associated with externalizing behaviors, such as age, gender, internalizing problems, and cognitive abilities. The results suggest that the ability to reflect on behaviors in terms of mental states predicted a sharper decrease in externalizing behaviors over time. Moreover, externalizing behaviors at the first assessment were associated with RF impairments and low affective empathy. Age, gender, cognitive abilities, and cognitive empathy were not associated with externalizing behaviors. We discuss how our results, based on a typically developing population, might inform primary or indicated prevention strategies for externalizing behaviors by focusing on socio-cognitive processes such as RF and affective empathy.

Optimal planned missing data design for linear latent growth curve models.

Longitudinal data collection is a time-consuming and cost-intensive part of developmental research. Wu et al. (2016) discussed planned missing (PM) designs that are similar in efficiency to complete designs but require fewer observations per person. The authors reported optimal PM designs for linear latent growth curve models based on extensive Monte Carlo simulations. They called for further formal investigation of the question as to how much the proposed PM mechanisms influence study design efficiency to arrive at a better understanding of PM designs. Here, we propose an approximate solution to the design problem by comparing the asymptotic effective errors of PM designs. Effective error was previously used to find optimal longitudinal study designs for complete data designs; here, we extend the approach to planned missing designs. We show how effective error is a metric for comparing the efficiency of study designs with both planned and unplanned missing data, and how earlier simulation-based results for PM designs can be explained by an asymptotic solution. Our approach is computationally more efficient than Wu et al.'s approach and leads to a better understanding of how various design factors, such as the number of measurement occasions, their temporal arrangement, attrition rates, and PM design patterns interact and how they conjointly determine design efficiency. We provide R scripts to calculate effective errors in various scenarios of PM designs.

Illness and intelligence are comparatively strong predictors of individual differences in depressive symptoms following middle age.

OBJECTIVE: We compared the importance of socio-demographic, lifestyle, health, and multiple cognitive measures for predicting individual differences in depressive symptoms in later adulthood. METHOD: Data came from 6203 community-dwelling older adults (age 41-93 years at study entry) from the United Kingdom. Predictors (36 in total) were assessed up to four times across a period of approximately 12 years. Depressive symptoms were measured with the Geriatric Depression Scale. Statistical methods included multiple imputation (for missing data), random forest analysis (a machine learning approach), and multivariate regression. RESULTS: On average, depressive symptoms increased gradually following middle age and appeared to accelerate in later life. Individual differences in depressive symptoms were most strongly associated with differences in combined symptoms of physical illness (positive relation) and fluid intelligence (negative relation). The strength of association between depressive symptoms and fluid intelligence was unaffected by differences in health status within a subsample of chronically depressed individuals. CONCLUSION: Joint consideration of general health status and fluid intelligence may facilitate prediction of depressive symptoms severity during later life and may also serve to identify sub-populations of community-dwelling elders at risk for chronic depression.

Fluid Intelligence Predicts Change in Depressive Symptoms in Later Life: The Lothian Birth Cohort 1936.

We examined reciprocal, time-ordered associations between age-related changes in fluid intelligence and depressive symptoms. Participants were 1,091 community-dwelling older adults from the Lothian Birth Cohort 1936 study who were assessed repeatedly at 3-year intervals between the ages of 70 and 79 years. On average, fluid intelligence and depressive symptoms worsened with age. There was also a dynamic-coupling effect, in which low fluid intelligence at a given age predicted increasing depressive symptoms across the following 3-year interval, whereas the converse did not hold. Model comparisons showed that this coupling parameter significantly improved overall fit and had a correspondingly moderately strong effect size, accounting on average for an accumulated 0.9 standard-deviation increase in depressive symptoms, following lower cognitive performance, across the observed age range. Adjustment for sociodemographic and health-related covariates did not significantly attenuate this association. This implies that monitoring for cognitive decrements in later life may expedite interventions to reduce related increases in depression risk.

Age Differences in Day-To-Day Speed-Accuracy Tradeoffs: Results from the COGITO Study.

We examined adult age differences in day-to-day adjustments in speed-accuracy tradeoffs (SAT) on a figural comparison task. Data came from the COGITO study, with over 100 younger and 100 older adults, assessed for over 100 days. Participants were given explicit feedback about their completion time and accuracy each day after task completion. We applied a multivariate vector auto-regressive model of order 1 to the daily mean reaction time (RT) and daily accuracy scores together, within each age group. We expected that participants adjusted their SAT if the two cross-regressive parameters from RT (or accuracy) on day t-1 of accuracy (or RT) on day t were sizable and negative. We found that: (a) the temporal dependencies of both accuracy and RT were quite strong in both age groups; (b) younger adults showed an effect of their accuracy on day t-1 on their RT on day t, a pattern that was in accordance with adjustments of their SAT; (c) older adults did not appear to adjust their SAT; (d) these effects were partly associated with reliable individual differences within each age group. We discuss possible explanations for older adults' reluctance to recalibrate speed and accuracy on a day-to-day basis.

The protective effect of a satisfying romantic relationship on women's body image after breast cancer: a longitudinal study.

OBJECTIVE: To examine the protective role of relationship satisfaction on body image in women with breast cancer throughout the first year post-surgery. METHODS: Seventy-four Swiss patients engaged in a relationship filled out a questionnaire assessing body image disturbance 2 weeks, 3 months, and 1 year after surgery. A univariate latent change score model was used to analyze the evolution of body image disturbance and the contribution of relationship satisfaction to body image disturbance. RESULTS: Women who were satisfied with their relationship reported less body image disturbance than did dissatisfied women at 2 weeks post-surgery. Being married was also associated with less body image disturbance at that time. The protective effect of these relational variables was still observable 1 year later. Changes in body image disturbance over time were explained by the negative impacts of mastectomy and chemotherapy. CONCLUSIONS: How women perceive the impact of breast cancer treatment on their body may be partly determined by the quality of the relational context in which they live.

Quantitative Methods in Psychological Aging Research: A Mini-Review.

As research on psychological aging moves forward, it is increasingly important to accurately assess longitudinal changes in psychological processes and to account for their (often complex) associations with sociodemographic, lifestyle, and health-related variables. Traditional statistical methods, though time tested and well documented, are not always satisfactory for meeting these aims. In this mini-review, we therefore focus the discussion on recent statistical advances that may be of benefit to researchers in psychological aging but that remain novel in our area of study. We first compare two methods for the treatment of incomplete data, a common problem in longitudinal research. We then discuss robust statistics, which address the question of what to do when critical assumptions of a standard statistical test are not met. Next, we discuss two approaches that are promising for accurately describing phenomena that do not unfold linearly over time: nonlinear mixed-effects models and (generalized) additive models. We conclude by discussing recursive partitioning methods, as these are particularly well suited for exploring complex relations among large sets of variables.

Performance-based everyday functional competence measures across the adult lifespan: the role of cognitive abilities.

BACKGROUND: The effects of age on the ability to manage everyday functioning, crucial to ensure a healthy aging process, have been rarely examined and when, self-report measures have been used. The aim of the present study was to examine age effects across the adult lifespan in everyday functioning with two performance-based measures: the Everyday Problems Test (EPT), and the Timed Instrumental Activities of Daily Living (TIADL) tasks. The role of some crucial cognitive abilities, i.e. working memory (WM), processing speed, reasoning, vocabulary, and text comprehension in the EPT and the TIADL were also assessed to see whether or not they have a similar influence (and to what extent) in accounting for age-related effects in these two performance-based measures. METHOD: Two hundred and seventy-six healthy participants, from 40 to 89 years of age were presented with the EPT, the TIADL, as well as WM, processing speed, reasoning, text comprehension, and vocabulary tasks. RESULTS: Path models indicated an indirect effect of age and education on the EPT, which was mediated by all the cognitive variables considered, with WM and reasoning being the strongest predictors of performance. An indirect quadratic effect of age, but not of education, was found on the TIADL score, and an accelerated decline in processing speed mediated the relationship between age and the TIADL score. CONCLUSION: This study revealed age-related effects in performance-based measures, which are mediated by different cognitive abilities depending on the measure considered. The findings highlight the importance of assessing everyday functioning even in healthy older adults.

Prospective memory and intraindividual variability in ongoing task response times in an adult lifespan sample: the role of cue focality.

To contribute to the ongoing conceptual debate of what traditional mean-level ongoing task (OT) costs tell us about the attentional processes underlying prospective memory (PM), we investigated costs to intraindividual variability (IIV) in OT response times as a potentially sensitive indicator of attentional processes. Particularly, we tested whether IIV in OT responses may reflect controlled employment of attentional processes versus lapses of controlled attention, whether these processes differ across adulthood, and whether it is moderated by cue focality. We assessed 150 individuals (19-82 years) in a focal and a nonfocal PM condition. In addition, external measures of inhibition and working memory were assessed. In line with the predictions of the lapses-of-attention/inefficient-executive-control account, our data support the view that costs to IIV in OT trials of PM tasks reflect fluctuations in the efficiency of executive functioning, which was related to failures in prospective remembering, particularly in nonfocal PM tasks, potentially due to their increased executive demands. The additional value of considering costs to IIV over and beyond traditional mean-level OT costs in PM research is discussed.

A Longitudinal Study of Parental Depressive Symptoms and Coparenting in the First 18 Months.

Although the negative impact of postpartum depression on parenting behaviors has been well established-albeit separately-for mothers and fathers, the respective and joint impact of both parents' mood on family-group interactive behaviors, such as coparenting support and conflict behaviors between the parents, have not yet been investigated. The aim of this study was to examine the association between parental depressive symptoms and coparenting behaviors in a low-risk sample of families with infants, exploring reciprocity between the variables, as well as gender differences between mothers and fathers regarding these links. At 3 (T1), 9 (T2), and 18 months postpartum (T3), we assessed both parents' depressive symptoms with a self-report questionnaire and observed coparenting support and conflict during triadic mother-father-child interactions. The results revealed that higher maternal depressive symptoms at T1 were associated with lower support at T1 and T2. Conflict at T3 was associated with higher maternal depressive symptoms at T3 and, more surprisingly, with less depressive symptoms in mothers at T2 and fathers at T3. Cross-lagged associations suggested that parental depressive symptoms were more likely to influence coparenting than the reverse. Moreover, maternal depressive symptoms were more likely to be linked to coparenting behaviors than were paternal depressive symptoms. These results confirm that parental-mostly maternal-depressive symptoms, even of mild intensity, may jeopardize the development of healthy family-level relations, which previous research has shown to be crucial for child development.

Regional brain shrinkage and change in cognitive performance over two years: The bidirectional influences of the brain and cognitive reserve factors.

We examined relationships between regional brain shrinkage and changes in cognitive performance, while taking into account the influence of chronological age, vascular risk, Apolipoprotein E variant and socioeconomic status. Regional brain volumes and cognitive performance were assessed in 167 healthy adults (age 19-79 at baseline), 90 of whom returned for the follow-up after two years. Brain volumes were measured in six regions of interest (ROIs): lateral prefrontal cortex (LPFC), prefrontal white matter (PFw), hippocampus (Hc), parahippocampal gyrus (PhG), cerebellar hemispheres (CbH), and primary visual cortex (VC), and cognitive performance was evaluated in three domains: episodic memory (EM), fluid intelligence (Gf), and vocabulary (V). Average volume loss was observed in Hc, PhG and CbH, but reliable individual differences were noted in all examined ROIs. Average positive change was observed in EM and V performance but not in Gf scores, yet only the last evidenced individual differences in change. We observed reciprocal influences among neuroanatomical and cognitive variables. Larger brain volumes at baseline predicted greater individual gains in Gf, but differences in LPFC volume change were in part explained by baseline level of cognitive performance. In one region (PFw), individual change in volume was coupled with change in Gf. Larger initial brain volumes did not predict slower shrinkage. The results underscore the complex role of brain maintenance and cognitive reserve in adult development.