Education and Cognitive Aging: Accounting for Selection and Confounding in Linkage of Data From the Danish Registry and Survey of Health, Ageing and Retirement in Europe

A nomogram to predict the risk of cognitive impairment in patients with depressive disorder

This study was to describe the cognitive function status in patients with depressive disorder and to construct a nomogram model to predict the risk factors of cognitive impairment in these patients. From October 2019 to February 2021, a total of 141 patients with depressive disorder completed the survey in two hospitals. The Montreal cognitive assessment (MoCA) was used with a cutoff score of 26 to differentiate cognitive impairment. Univariable and multivariable logistic regression analyses were conducted to identify independent risk factors. A nomogram was then constructed based on the results of the multivariable logistic regression analysis. The patients had an average MoCA score of 23.99 ± 3.02. The multivariable logistic regression analysis revealed that age (OR: 1.096, 95% CI: 1.042-1.153, p < 0.001), education (OR: 0.065, 95% CI: 0.016-0.263, p < 0.001), depression severity (OR: 1.878, 95% CI: 1.021-3.456, p = 0.043), and sleep quality (OR: 2.454, 95% CI: 1.400-4.301, p = 0.002) were independent risk factors for cognitive impairment in patients with depressive disorder. The area under receiver operating characteristic (ROC) curves was 0.868 (95% CI: 0.807-0.929), indicating good discriminability of the model. The calibration curve of the model and the Hosmer-Lemeshow test (p = 0.571) demonstrated a well-fitted model with high calibration. Age, education, depression severity, and sleep quality were found to be significant predictors of cognitive function. A nomogram model was developed to predict cognitive impairment in patients with depressive disorder, providing a solid foundation for clinical interventions.

My Parent, Myself, or My Child: Whose Education Matters Most for Trajectories of Cognitive Aging in Middle Age?

The growing body of evidence linking intergenerational education and late-life cognitive decline is almost exclusively from high-income countries, despite rapid intergenerational changes in education in low- and middle-income countries (LMICs). We used data from the Mexican Health and Aging Study (n = 8,822), a cohort study of Mexican adults aged ≥50 years (2001-2018), to evaluate whether parental education (none vs. any formal schooling), one's own education (less than primary school vs. completion of primary school), or an adult child's education (less than high school vs. completion of high school) was associated with verbal memory z scores. We used linear mixed models with inverse probability of attrition weights. Educational attainment in all 3 generations was associated with baseline verbal memory scores, independent of the prior generation's education. Lower parental (β = -0.005, 95% confidence interval: -0.009, -0.002) and respondent (β = -0.013, 95% confidence interval: -0.017, -0.010) educational level were associated with faster decline in delayed (but not immediate) verbal memory z scores. Associations between adult child's education and respondent's verbal memory decline varied by exposure specification. The educational attainment of parents and adult children may influence the cognitive aging of middle-aged and older adults in LMICs. These results have important implications given recent structural shifts in educational attainment in many LMICs.

The Mediating Effects of Education and Occupational Complexity Between Race and Longitudinal Change in Late Life Cognition in ACTIVE

This study examined educational and occupational inequality as two aspects of social determinants of health that might mediate the longitudinal relationship between racialization and late life cognitive level and change. Participants were 2371 individuals racialized as Black and White from the ACTIVE study who provided occupational data. Data were analyzed from baseline and five assessments over 10-years using structural equation modeling. Black/White race served as the predictor, occupational complexity (OC) and years of education as mediators, and cognitive (memory, reasoning, and speed of processing) intercept, linear slope, and quadratic slope as the dependent variables. Black/White race showed significant indirect associations through education and OC on level of performance in cognition, linear change in reasoning and memory, and quadratic change in reasoning. Education and OC accounted for 11-16% of the association between race and cognitive level and represent modifiable social determinants of health that are associated with disparities in cognitive aging.

Cerebral Small Vessel Disease: Early-Life Antecedents and Long-Term Implications for the Brain, Aging, Stroke, and Dementia

Cerebral small vessel disease is common in older adults and increases the risk of stroke, cognitive impairment, and dementia. While often attributed to midlife vascular risk factors such as hypertension, factors from earlier in life may contribute to later small vessel disease risk. In this review, we summarize current evidence for early-life effects on small vessel disease, stroke and dementia focusing on prenatal nutrition, and cognitive ability, education, and socioeconomic status in childhood. We discuss possible reasons for these associations, including differences in brain resilience and reserve, access to cognitive, social, and economic resources, and health behaviors, and we consider the extent to which these associations are independent of vascular risk factors. Although early-life factors, particularly education, are major risk factors for Alzheimer disease, they are less established in small vessel disease or vascular cognitive impairment. We discuss current knowledge, gaps in knowledge, targets for future research, clinical practice, and policy change.

Association Between Body Mass Index and Cognitive Function Among Older Adults in India: Findings from a Cross-Sectional Study

OBJECTIVE

The study aimed to explore the association between body mass index (BMI) and cognitive function among older adults in India.

METHODS

Cross-sectional data on 21,000 older adults aged 60 years and older from the first wave of the Longitudinal Ageing Study of India (LASI), conducted in India during 2017-18, were used. Bivariate analysis and multivariate linear regression models were applied. The cognition tests include memory, orientation, arithmetic function, executive function, and object naming.

RESULTS

The mean overall cognition score was 24.6 in the study population. Further, BMI status showed a significant and positive association with cognition. The association of underweight with poor cognition (β=-0.72; 95% CI = -0.89, -0.54) whereas overweight (β = 0.57; 95% CI = 0.39, 0.75) and obese (β = 0.97; 95% CI = 0.68, 1.26) with better cognition remained statistically significant after adjusting for sociodemographic, health-related behavior, and health covariates. The mean cognition score of female older adults was always lower than male older adults with normal BMI, irrespective of their BMI categories.

CONCLUSIONS

This study shows that an underweight BMI is associated with poor cognition in both male and female older adults. In the context of providing health care for older individuals, underweight individuals should be given more attention in India.

Bidirectional Association Between Multimorbidity and Frailty and the Role of Depression in Older Europeans

BACKGROUND

Although previous studies have reported an association between multimorbidity and frailty, its direction and mechanism remain unclear. This study aimed to investigate the direction of this association, as well as the role of depression among older Europeans.

METHODS

We used a cross-lagged panel design to evaluate the temporal relationship between multimorbidity and frailty and the role of depression. Multimorbidity status was assessed by the self-reporting of 14 chronic diseases. Frailty was assessed based on the frailty phenotype. The European-Depression Scale (EURO-D) was used to assess depression.

RESULTS

There was a bidirectional relationship between frailty and multimorbidity. More severe multimorbidity predicted greater frailty (β = 0.159; p < .001) and vice versa (β = 0.107; p < .001). All paths from multimorbidity to frailty were stronger than the paths from frailty to multimorbidity (b1-a1: β = 0.051; p < .001). Likewise, early multimorbidity change was a significant predictive factor for late frailty change (β = 0.064; p < .001) and vice versa (β = 0.048; p < .001). Depression in Wave 5 (T5) mediated the association between frailty in Wave 4 (T4) and multimorbidity in Wave 6 (T6; indirect effect: β = 0.004; bootstrap 95% confidence interval: 0.003, 0.006).

CONCLUSIONS

A positive, bidirectional association was observed between multimorbidity and frailty. Depression may be a potential cause of an increased risk of multimorbidity later in life in frail older adults. Early monitoring of frailty and depression may slow the progression of multimorbidity, thereby interrupting the vicious cycle.

Life Course Socioeconomic Position and Cognitive Aging Trajectories: A Cross-National Cohort Study in China and England

Background and Objectives

Cross-national research on cognitive aging inequality has largely concentrated on Western countries. It is unclear whether socioeconomic position (SEP) has similar effects on cognitive decline in emerging economies. We compared the association between life course SEP and cognitive function trajectories between China and England, the largest nation under state socialism and one of the oldest capitalist countries.

Research Design and Methods

This cross-cohort study examined participants aged 50 years and older from the China Health and Retirement Longitudinal Study (n = 12,832) and the English Longitudinal Study of aging (n = 8,875). Cognition z-scores were derived using comparable measures of memory and time orientation on 4 occasions. Life course SEP was self-reported by participants at baseline. Seven- to 8-year trajectories of cognition z-scores were estimated using latent growth curve modeling. Country- and gender-specific associations between childhood/adolescent deprivation, education, material wealth, and home ownership were evaluated in relation to model intercept (baseline level) and linear slope (annual rate of change) of cognition.

Results

After multivariable adjustment, education was positively associated with the greatest differences in baseline cognition across country and gender. Education was further linked to a slower rate of cognitive decline (z-score units per year); but compared with those with low education, Chinese men (b = 0.032) and women (b = 0.065) with high education had significantly slower declines than English men (b = -0.004) and women (b = 0.010) with high education.

Discussion and Implications

Despite substantial between-cohort differences in downstream and upstream determinants of dementia, education provided the greatest benefits to cognitive aging in England but particularly in China.

Verbal ability in postmenopausal women in relation to age, cognitive and reproductive factors

Word-finding difficulties have been associated with age and, in women, lowered sex hormone levels following menopause. However, there is limited understanding of the ways that specific aspects of word-finding are shaped by women's age, reproductive histories, and background factors such as education. The current study investigated the effects of age, cognitive and reproductive factors on word-finding abilities in 53 healthy postmenopausal women aged 48-79. A questionnaire was used to gather demographic information and reproductive history. A battery of verbal fluency, continuous series, and naming tasks was designed to assess word-finding across different sensory modalities and cognitive demands. Category and letter fluency were quantified as total number of correct words produced on each task. For continuous series, switch rates and switch costs were computed. For the naming tasks, accuracy and latency measures were used. There were three key findings. Firstly, there was a consistent positive association between education and all word-finding measures, i.e., verbal fluency, continuous series, and naming. Secondly, age-related declines were seen on tasks heavily dependent on working memory such as the continuous series task. Thirdly, reproductive factors across the lifespan such as age at menarche and reproductive years showed subtle effects on naming abilities, but not on verbal fluency or continuous series. The results highlight that word-finding abilities in healthy postmenopausal women are shaped by factors associated with their early years (education, age at menarche) and later adult life (age, reproductive years). The study also distinguished between the more global effects of education, and the more task-specific associations with age and reproductive variables, on verbal task performance after menopause.

The Longitudinal Association Between Frailty, Cognition, and Quality of Life in Older Europeans

OBJECTIVES

Evidence on the association between frailty and quality of life (QoL) is mostly limited to cross-sectional studies. Thus, the temporal order and potential mechanisms of this association are largely unknown. Our study examines both the directionality of this association and the role of cognition in this association in longitudinal data.

METHODS

Cross-lagged panel models were employed to examine the temporal relationship between frailty and QoL, as well as cognition's role among 19,649 older adults in Europe. Frailty, QoL, and cognition were assessed using the health deficit index, CASP-12, and 3 standard cognitive tests, respectively.

RESULTS

We observed a bidirectional association between frailty and QoL and their dynamics. High initial levels of frailty predicted poorer QoL later and vice versa (β = -0.151 and -0.052, p < .001). The early change in frailty predicted the late change in QoL, and vice versa (β = -0.093 and -0.061, p < .001). Frailty or its early change drives this interrelationship. Cognition at Wave 5 partially mediated frailty's effect at Wave 4 on QoL at Wave 6 (indirect effect: β = -0.005, 95% confidence interval = -0.006, -0.004).

DISCUSSION

Our findings supported that early prevention of frailty and its risk factors may have more influential protective effects on later physical and mental health, as well as the need for ongoing screening for mental health in aging population. Also, the maintenance of good cognitive performance may help interrupt this possible vicious cycle linking frailty and QoL decline.

Metrological properties of neuropsychological tests for measuring cognitive change in individuals with prodromal Alzheimer's disease

OBJECTIVES

In Alzheimer's Disease (AD) research, choosing appropriate method for measuring change in cognitive function over time can be challenging. The aim for this study was to examine the sensitivity of four neuropsychological tests used to measure cognition during the transition from mild cognitive impairment (MCI) to AD, and the impacts of associated covariates.

METHODS

We enrolled 223 patients with MCI who progressed to AD and had completed multiple follow-up assessments in the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. We constructed nonlinear mixed model for multivariate longitudinal data assuming that multiple neuropsychological tests would exhibit nonlinear transformation of a common factor in the latent cognitive process underlying the progression from MCI to AD.

RESULTS

The Clinical Dementia Rating-Sum of the Boxes (CDR-SB) and Alzheimer's Disease Assessment Scale (11 items; ADAS-11) were more sensitive to cognitive changes in individuals with higher cognitive function, the Functional Activities Questionnaire (FAQ) was more sensitive to cognitive changes in individuals with middle cognitive function, and the Mini-Mental State Examination (MMSE) was more sensitive to cognitive changes in individuals with lower cognitive function. Gender (p = 0.0139) and educational level (p = 0.0094) had varying effects on different tests, such that men performed better on the FAQ and CDR-SB, and individuals with higher educational level tended to perform better on the FAQ and MMSE.

CONCLUSIONS

When choosing appropriate neuropsychological tests in cognitive measurements, the cognitive functional level of the patient as well as the impacts of covariates should be considered.

Joint Models for Estimating Determinants of Cognitive Decline in the Presence of Survival Bias

BACKGROUND

Identifying determinants of cognitive decline is crucial for developing strategies to prevent Alzheimer's disease and related dementias. However, determinants of cognitive decline remain elusive, with inconsistent results across studies. One reason could be differential survival. Cognitive decline and many exposures of interest are associated with mortality making survival a collider. Not accounting for informative attrition can result in survival bias. Generalized estimating equations (GEE) and linear mixed-effects model (LME) are commonly used to estimate effects of exposures on cognitive decline, but both assume mortality is not informative. Joint models combine LME with Cox proportional hazards models to simultaneously estimate cognitive decline and the hazard of mortality.

METHODS

Using simulations, we compared estimates of the effect of a binary exposure on rate of cognitive decline from GEE, weighted GEE using inverse-probability-of-attrition weights, and LME to joint models under several causal structures of survival bias.

RESULTS

We found that joint models with correctly specified relationship between survival and cognition performed best, producing unbiased estimates and appropriate coverage. Even those with misspecified relationship between survival and cognition showed advantage under causal structures consistent with survival bias. We also compared these models in estimating the effect of education on cognitive decline after dementia diagnosis using Framingham Heart Study data. Estimates of the effect of education on cognitive decline from joint models were slightly attenuated with similar precision compared with LME.

CONCLUSIONS

In our study, joint models were more robust than LME, GEE, and weighted GEE models when evaluating determinants of cognitive decline.

Digitally Savvy at the Home Office: Computer Skills of Older Workers During the COVID-19 Pandemic Across Europe

Digital skills can be a valuable resource in work life, especially in such times as the current COVID-19 pandemic, during which working from home has become new reality. Although increasing numbers of older employees (aged 50 years and above) are using digital technologies to work remotely, many of these older adults still have generally lower digital skills. Whether the pandemic will be a push factor for the acquisition of computer skills in late working life remains unclear. This study investigated the explanatory factors of the computer skills gained by older workers who were working from home during the COVID-19 pandemic, using representative data for 28 countries from the Survey of Health, Aging and Retirement in Europe (SHARE). The analysis of the survey responses of 11,042 employed persons aged 50 years and older revealed that, 13% worked only at home due to the pandemic, while 15% said they worked at home and in their usual workplace. The descriptives indicate that full-time homeworking is more of an option among those with tertiary education and who already have some computer skills. Of the older employees who worked only at home, 36% reported an improvement in their computer skills, whereas of the older workers who worked at home and at their usual workplaces, only 29% reported such an improvement. Our results based on logistic regressions suggest that significantly more women, younger employees, respondents with tertiary educational qualifications, and those whose work was not affected by unemployment or even business closure acquired new computer skills, regardless of whether they were working permanently or only partly from home. The study underlines the importance of investigating the possible digital skills gained from the home office situation resulting from the pandemic.

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.

Educational attainment and trajectories of cognitive decline during four decades-The Glostrup 1914 cohort

Background

The potential association between level of education and age-related cognitive decline remains an open question, partly because of a lack of studies including large subsamples with low education and follow-up intervals covering a substantial part of the adult lifespan.

Objectives

To examine cognitive decline assessed by a comprehensive clinical test of intelligence over a 35-year period of follow-up from ages 50 to 85 and to analyze the effect of education on trajectories of cognitive decline, including the effects of selective attrition.

Methods

A longitudinal cohort study with a 35-year follow-up of community dwelling members of the Glostrup 1914 cohort. The study sample comprised 697 men and women at the 50-year baseline assessment and additional participants recruited at later follow-ups. Verbal, Performance, and Full Scale IQs were assessed using the Wechsler Adult Intelligence Scale at ages 50, 60, 70, 80, and 85. To be able to track cognitive changes between successive WAIS assessments, all IQs were based on the Danish 50-year norms. Information on school education was self-reported. The association between education and cognitive decline over time was examined in growth curve models. Selective attrition was investigated in subsamples of participants who dropped out at early or later follow-ups.

Results

The trajectories for Verbal, Performance, and Full Scale IQ showed higher initial cognitive performance, but also revealed steeper decline among participants with a formal school exam compared to participants without a formal exam. Verbal IQ showed the largest difference in level between the two educational groups, whereas the interaction between education and age was stronger for Performance IQ than for Verbal IQ. In spite of the difference in trajectories, higher mean IQ was observed among participants with a formal school exam compared to those without across all ages, including the 85-year follow-up.

Further analyses revealed that early dropout was associated with steeper decline, but that this effect was unrelated to education.

Conclusion

Comprehensive cognitive assessment over a 35-year period suggests that higher education is associated with steeper decline in IQ, but also higher mean IQ at all follow-ups. These findings are unlikely to reflect regression towards the mean, other characteristics of the employed test battery or associations between educational level and study dropout.

Development and validation of the type 2 diabetes mellitus 10-year risk score prediction models from survey data

AIMS

In this paper, we demonstrate the development and validation of the 10-years type 2 diabetes mellitus (T2DM) risk prediction models based on large survey data.

METHODS

The Survey of Health, Ageing and Retirement in Europe (SHARE) data collected in 12 European countries using 53 variables representing behavioural as well as physical and mental health characteristics of the participants aged 50 or older was used to build and validate prediction models. To account for strongly unbalanced outcome variables, each instance was assigned a weight according to the inverse proportion of the outcome label when the regularized logistic regression model was built.

RESULTS

A pooled sample of 16,363 individuals was used to build and validate a global regularized logistic regression model that achieved an area under the receiver operating characteristic curve of 0.702 (95% CI: 0.698-0.706). Additionally, we measured performance of local country-specific models where AUROC ranged from 0.578 (0.565-0.592) to 0.768 (0.749-0.787).

CONCLUSIONS

We have developed and validated a survey-based 10-year T2DM risk prediction model for use across 12 European countries. Our results demonstrate the importance of re-calibration of the models as well as strengths of pooling the data from multiple countries to reduce the variance and consequently increase the precision of the results.

Association of life course socioeconomic status and adult height with cognitive functioning of older adults in India and China

BACKGROUND

Cognitive functioning is an important measure of intrinsic capacity. In this study, we examine the association of life course socioeconomic status (SES) and height with cognitive functioning among older adults (50+) in India and China. The age pattern of cognitive functioning with measures of life course socioeconomic status has also been examined.

METHODS

Cross-sectional comparative analysis was conducted using the WHO's Study on global AGEing and adult health (SAGE) data for India and China. Multilevel mixed-effect linear regression analysis was used to examine the association of life course socioeconomic status and adult height with cognitive functioning.

RESULTS

In both India and China, parental education as a measure of childhood socioeconomic status was positively associated with cognitive functioning. The association between adult socioeconomic status and cognitive functioning was positive and significant. Height was significantly and positively associated with improved cognitive functioning of older adults in India and China. Furthermore, the age-related decline in cognitive functioning score was higher among older adults whose parents had no schooling, particularly in China. The cognitive functioning score with age was much lower among less-educated older adults than those with higher levels of education in China. Wealthier older adults in India had higher cognitive functioning in middle ages, however, wealth differences narrowed with age.

CONCLUSIONS

The results of this study suggest a significant association of lifetime socioeconomic status and cumulative net nutrition on later-life cognitive functioning in middle-income settings.

Inequality of educational opportunity at time of schooling predicts cognitive functioning in later adulthood

Objectives

Our understanding of how societal conditions and educational policies influence cognitive development across the life course is improving. We tested the extent to which inequality of educational opportunity (IEO), the country- and cohort-specific correlation of parents' and their offspring's length of schooling, offers systematically different opportunities to contribute to cognitive development, which in turn influences cognitive abilities up to older ages.

Methods

A total of 46,972 individuals of three cohorts born 1940-63 from 16 European countries and Israel provided up to six cognitive assessments and information on covariates in the SHARE survey 2004-2017. Individual-level data were linked to indicators of IEO at time of schooling, and economic, health, and human development, provided by World Bank, WHO, and the UN.

Results

In multilevel (mixed-effects) models with random individual and country-cohort effects and adjusted for a large set of confounders, higher IEO was associated with lower levels of cognitive functioning in men and women. Interaction analyses suggested lower cognitive levels particularly of women who were schooled in higher IEO contexts and had lower educational attainment. Associations with rate of change in cognitive functioning were present only in women, however there was little clinically relevant cognitive decline across the window of observation. Result patterns were mostly consistent after including additional contextual indicators, and in a subsample with childhood information.

Discussion

Findings suggest that IEO is able to substantially influence cognitive development with long-lasting impacts. Lower-educated women of the cohorts under investigation may have been particularly vulnerable to high-inequality educational contexts.

Adverse childhood circumstances and cognitive function in middle-aged and older Chinese adults: Lower level or faster decline?

We examine the long-term relationship between childhood circumstances and cognitive aging. In particular, we differentiate the level of cognitive deficit from the rate of cognitive decline. Applying a linear mixed-effect model to three waves of China Health and Retirement Longitudinal Surveys (CHARLS 2011, 2013, 2015) and matching cognitive outcomes to CHARLS Life History Survey (2014), we find that key domains of childhood circumstances, including family socioeconomic status (SES), neighborhood cohesion, friendship, and health conditions, are significantly associated with both the level of cognitive deficit and the rate of decline. In contrast, childhood neighborhood safety only affects the level of cognitive deficit. Childhood relationship with mother only affects the rate of cognitive decline. The effects of adverse childhood circumstances are generally larger on level of cognitive deficit than on rate of cognitive decline. Moreover, education plays a more important role in mediating the relationships compared to other later-life factors. These findings suggest that exposure to disadvantaged childhood circumstances can exacerbate cognitive deficit as well as cognitive decline over time, which may be partially ameliorated by educational attainment.

Women's Work-Family Histories and Cognitive Performance in Later Life

Long-term exposures to the stress and stimulation of different work, parenting, and partnership combinations might influence later life cognition. We investigated the relationship between women's work-family life histories and cognitive functioning in later life. Analyses were based on data from women born between 1930 and 1957 in 14 European countries, from the Survey of Health, Ageing and Retirement in Europe (2004-2009) (n = 11,908). Multichannel sequence analysis identified 5 distinct work-family typologies based on women's work, partnership, and childrearing statuses between ages 12 and 50 years. Multilevel regressions were used to test the association between work-family histories and later-life cognition. Partnered mothers who mainly worked part-time had the best cognitive function in later life, scoring approximately 0.63 (95% confidence interval (CI): 0.18, 1.07) points higher than mothers who worked full-time on a 19-point scale. Partnered mothers who were mainly unpaid caregivers or who did other unpaid activities had cognitive scores that were 1.19 (95% CI: 0.49, 1.89) and 0.93 (95% CI: 0.20, 1.66) points lower than full-time working mothers. The findings are robust to adjustment for childhood advantage and educational credentials. This study provides new evidence that long-term exposures to certain social role combinations after childhood and schooling are linked to later-life cognition.

Education and Cognitive Decline: An Integrative Analysis of Global Longitudinal Studies of Cognitive Aging

BACKGROUND

The objective of this study was to examine the association between education and incidence of accelerated cognitive decline.

METHODS

Secondary analyses of data from the Health and Retirement Study (HRS), a nationally representative prospective cohort study of U.S. residents were conducted (N = 28,417). Cox proportional hazards survival models were layered on longitudinal mixed-effects modeling to jointly examine healthy cognitive aging and incidence of accelerated cognitive decline consistent with patterns seen in preclinical Alzheimer's disease and related dementias (ADRD). Replication analyses were completed on a database including 62,485 additional respondents from HRS sister studies. Life expectancy ratios (LER) and 95% confidence intervals (CIs) were reported.

RESULTS

This study replicated research showing that education was positively associated with cognition at baseline. Model fit improved using the survival method compared to random-slopes models alone. Analyses of HRS data revealed that higher education was associated with delayed onset of accelerated cognitive decline (LER = 1.031 95% CI = [1.013-1.015], p < 1E-06). Replication analyses using data from 14 countries identified similar results.

CONCLUSIONS

These results are consistent with cognitive reserve theory, suggesting that education reduces risk of ADRD-pattern cognitive decline. Follow-up work should seek to differentiate specific dementia types involved and consider potential mechanisms.

Education and Cognitive Functioning Across the Life Span

Cognitive abilities are important predictors of educational and occupational performance, socioeconomic attainment, health, and longevity. Declines in cognitive abilities are linked to impairments in older adults' everyday functions, but people differ from one another in their rates of cognitive decline over the course of adulthood and old age. Hence, identifying factors that protect against compromised late-life cognition is of great societal interest. The number of years of formal education completed by individuals is positively correlated with their cognitive function throughout adulthood and predicts lower risk of dementia late in life. These observations have led to the propositions that prolonging education might (a) affect cognitive ability and (b) attenuate aging-associated declines in cognition. We evaluate these propositions by reviewing the literature on educational attainment and cognitive aging, including recent analyses of data harmonized across multiple longitudinal cohort studies and related meta-analyses. In line with the first proposition, the evidence indicates that educational attainment has positive effects on cognitive function. We also find evidence that cognitive abilities are associated with selection into longer durations of education and that there are common factors (e.g., parental socioeconomic resources) that affect both educational attainment and cognitive development. There is likely reciprocal interplay among these factors, and among cognitive abilities, during development. Education-cognitive ability associations are apparent across the entire adult life span and across the full range of education levels, including (to some degree) tertiary education. However, contrary to the second proposition, we find that associations between education and aging-associated cognitive declines are negligible and that a threshold model of dementia can account for the association between educational attainment and late-life dementia risk. We conclude that educational attainment exerts its influences on late-life cognitive function primarily by contributing to individual differences in cognitive skills that emerge in early adulthood but persist into older age. We also note that the widespread absence of educational influences on rates of cognitive decline puts constraints on theoretical notions of cognitive aging, such as the concepts of cognitive reserve and brain maintenance. Improving the conditions that shape development during the first decades of life carries great potential for improving cognitive ability in early adulthood and for reducing public-health burdens related to cognitive aging and dementia.

Relationship Between Mental Health and the Education Level in Elderly People: Mediation of Leisure Attitude

Purpose

The present study intends to explore the influence of education on the mental health of retired people and the mediating role of a leisure attitude in this relationship.

Design/Methodology

The sample was simple random, and a confidentiality agreement was established. The sample was composed of 403 Portuguese participants (37.2% male; 62.8% female). The participants completed the MHI and the LAS.

Findings

The hypothesized mediation model showed that a leisure attitude mediated the association between education and well-being. In addition, higher levels of distress were found in participants with higher levels of education.

Scientific Contribution

Our results suggest that old-aged people with high education and a more positive leisure attitude have a better psychological adjustment concerning well-being. Also, a higher level of education can lead to a better perception of aging changes (physical, life, profession).

Education and age-related decline in cognitive performance: Systematic review and meta-analysis of longitudinal cohort studies

Central theories of cognitive aging propose that education is an important protective factor for decline in cognitive performance in older age. We conducted a systematic review and meta-analysis of reported estimates of an association between educational attainment and change in performance in six cognitive domains (episodic memory, processing speed, verbal fluency, crystallized intelligence, fluid intelligence, and global ability) in the general population of older individuals. The systematic search (11^th of October 2019) identified 92 eligible articles. The episodic memory domain had the highest number of estimates (37 estimates from 18 articles, n = 109,281) included in the meta-analysis. The fewest estimates (6 estimates from 6 articles, n = 5263) were included for fluid intelligence. Pooled mean estimates from an inverse-variance weighted random effects analysis were not statistically significant and indicated that any association between education and change in cognitive performance is likely of a negligible magnitude. The estimates for education's role (one additional year) for change in cognitive performance ranged from -0.019 (95 % confidence interval, CI = -0.047, 0.010) to 0.004SD (CI = -0.003, 0.012) per decade. Even if the larger positive point estimates (i.e., protective effects) are selectively considered, the influence of education on change is still at least 12 times less important for the cognitive functioning of an older individual than the association between education and level of cognitive performance. Sensitivity analyses did not substantially alter these results. However, heterogeneity was substantial, and remained largely unexplained by mean age, mean educational attainment, Gini coefficient, GDP per capita, maximum follow-up period, and publication year. Overall, education is an important factor in aging due to its robust association with level of performance, but the current base of empirical evidence is not revealing a consistent and substantial association between educational attainment and changes in cognitive performance in the general population. Theories of cognitive aging must be updated to incorporate this pattern of findings.

The relationship between cognitive decline and a genetic predictor of educational attainment

Genetic and environmental factors both make substantial contributions to the heterogeneity in individuals’ levels of cognitive ability. Many studies have examined the relationship between educational attainment and cognitive performance and its rate of change. Yet there remains a gap in knowledge regarding whether the effect of genetic predictors on individual differences in cognition becomes more or less prominent over the life course. In this analysis of over 5000 older adults from the Health and Retirement Study (HRS) in the U.S., we measured the change in performance on global cognition, episodic memory, attention & concentration, and mental status over 14 years. Growth curve models are used to evaluate the association between a polygenic risk score for education (education PGS) and cognitive change. Using the most recent education PGS, we find that individuals with higher scores perform better across all measures of cognition in later life. Education PGS is associated with a faster decline in episodic memory in old age. The relationships are robust even after controlling for phenotypic educational attainment, and are unlikely to be driven by mortality bias. Future research should consider genetic effects when examining non-genetic factors in cognitive decline. Our findings represent a need to understand the mechanisms between genetic endowment of educational attainment and cognitive decline from a biological angle.

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Older adults with higher scores perform better across all measures of cognition.

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The relationship is robust after controlling for phenotypic educational attainment.

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The genetic effect on episodic memory diminishes with age.

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Future research should consider genetic effects when examining cognitive decline.

Sex Differences in the Genetic Architecture of Alzheimer's Disease

PURPOSE OF REVIEW

Summarize sex-specific contributors to the genetic architecture of Alzheimer's disease (AD).

RECENT FINDINGS

There are sex differences in the effects of Apolipoprotein E (APOE), genes along the APOE pathway, and genes along the neurotrophic signaling pathway in predicting AD. Reported sex differences are largely driven by stronger associations among females. Evidence also suggests that genetic predictors of amyloidosis are largely shared across sexes, while sex-specific genetic effects emerge downstream of amyloidosis and drive the clinical manifestation of AD.

SUMMARY

There is a lack of comprehensive assessments of sex differences in genome-wide analyses of AD and a need for more systematic reporting a sex-stratified genetic effects. The emerging emphasis on sex as a biological variable provides an opportunity for transdisciplinary collaborations aimed at addressing major analytical challenges that have hampered advancements in the field. Ultimately, sex-specific genetic association studies represent a logical first step towards precision medicine.

School Performance and Educational Attainment as Early-Life Predictors of Age-Related Memory Decline: Protective Influences in Later-Born Cohorts

Objectives

Evidence is accumulating that early-life characteristics and experiences contribute significantly to differences in cognitive aging. This study investigated whether school performance at age 12 predicted late-life level and rate of memory change over 15–25 years, and whether its potential protective influence on memory change was mediated by educational attainment or income.

Methods

Latent growth curve models were fitted to 15–25 year longitudinal memory data from a population-based sample, stratified on age cohorts (n = 227, born 1909–1935; n = 301, born 1938–1954).

Results

A latent-level school grade variable significantly predicted both memory level and slope in later-born cohorts. Higher grades were associated with higher level and reduced decline, measured between ages 45 and 70 years, on average. In the earlier-born cohorts, grades predicted memory level, but not slope, measured between ages 66 and 81 years. Follow-up analyses indicated that the protective influence of higher school grades in later-born cohorts was partially mediated by educational attainment, but independent of income.

Discussion

The results suggest that higher childhood school performance is protective against age-related cognitive decline in younger or later-born cohorts, for which further education has been more accessible. Education may exert such influence through increased cognitive reserve or more well-informed health- and lifestyle decisions.