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

Can Neighborhood Social Infrastructure Modify Cognitive Function? A Mixed-Methods Study of Urban-Dwelling Aging Americans

Objectives: Socialization predicts cognitive aging outcomes. Neighborhoods may facilitate socially engaged aging and thus shape cognition. We investigated places where older adults socialized and whether availability of these sites was associated with cognitive outcomes. Methods: Qualitative analysis of interviews and ethnography with 125 older adults (mean age 71 years) in Minneapolis identified where participants socialized outside of home. This informed quantitative analysis of a national sample of 21,151 older Americans (mean age at baseline 67 years) from the Reasons for Geographic and Racial Differences in Stroke study. Multilevel generalized additive models described associations between access to key social places and cognitive function and decline. Results: Qualitative analysis identified eateries, senior centers, and civic groups as key places to socialize. We identified significant positive associations between kernel density of senior centers, civic/social organizations, and cognitive function. Discussion: Specific neighborhood social infrastructures may support cognitive health among older adults aging in place.

The effects of education on cognition in older age: Evidence from genotyped Siblings

A growing literature has sought to tie educational attainment with later-life cognition and Alzheimer's disease outcomes. This paper leverages sibling comparisons in educational attainment as well as genetic predictors (polygenic scores) for cognition, educational attainment, and Alzheimer's disease to estimate effects of educational attainment on cognition in older age in the United Kingdom. We find that the effects of education on cognition are confounded by family background factors (~40%) and by genetics (<10%). After adjustments, we continue to find large effects of education. College graduates have cognition scores that are approximately 0.75 SD higher than those who report no credentials. We also find evidence that educational effects on cognition are smaller for those with high polygenic scores for Alzheimer's disease.

Duration of subjective poverty in relation to subsequent cognitive performance and decline among adults aged ≥64 in China, 2005-2018

BACKGROUND

The effects of late-life subjective poverty on brain health are understudied. We aimed to investigate the association between duration of subjective poverty after age 64 and subsequent cognitive function and decline in China.

METHODS

Data were from 4118 adults aged ≥64 at baseline in the population-based China Longitudinal Healthy Longevity Survey (CLHLS), 2005-2018. The duration of subjective poverty was measured from self-rated economic status relative to neighbors in 2005, 2008, and 2011 (never; one time point; two or three time points). Cognitive function was assessed by the Chinese Mini-Mental State Exam (CMMSE; range: 0-30) in 2011, 2014, and 2018. We fitted attrition-weighted, multivariable mixed-effects Tobit regression models to examine the relationship between duration of subjective poverty from 2005 to 2011 and subsequent cognitive function and decline from 2011 to 2018.

RESULTS

A total of 2675 (64.96%) participants never reported subjective poverty over the period 2005-2011, 930 (22.58%) participants reported subjective poverty at one time point, and 513 (12.46%) reported subjective poverty at two or three time points. Compared to those who never reported subjective poverty, participants experiencing subjective poverty at one time point (β = -0.95, 95% CI: -1.48 to -0.41) and two or three time points (β = -2.01; 95% CI: -2.73 to -1.29) had lower CMMSE scores in 2011, indicating a dose-response relationship. Individuals with a longer duration of subjective poverty had a slower rate of decline in CMMSE scores than those never in subjective poverty (β = 1.44; 95% CI: 0.20 to 2.68 for 2018 X Two or three time points).

CONCLUSION

Subjective poverty in late life may have unique and cumulative contributions to cognitive aging among older adults in China. The lower level of initial cognitive function but slower rate of cognitive decline observed for those with greater subjective poverty is consistent with theories of cognitive reserve and empirical evidence from Western settings on other socioeconomic markers.

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.

Duration of Poverty and Subsequent Cognitive Function and Decline Among Older Adults in China, 2005-2018

OBJECTIVE

To investigate the relationship between late-life duration of poverty exposure and cognitive function and decline among older adults in China.

METHODS

Data were from 3,209 participants ≥64 years of age in the Chinese Longitudinal Healthy Longevity Survey (CLHLS). Duration of poverty, defined according to urban and rural regional standards from the China Statistical Yearbook, was assessed according to annual household income from 2005 to 2011 (never in poverty; one-third of the period in poverty; two-thirds or more of the period in poverty). Cognitive function was measured by the Chinese Mini-Mental State Examination (CMMSE) from 2011 to 2018. We used attrition-weighted, multivariable mixed-effects Tobit regression to examine the association of duration of poverty with cognitive function and rate of decline.

RESULTS

A total of 1,162 individuals (36.21%) were never in poverty over the period from 2005 to 2011; 1,172 (36.52%) were in poverty one-third of the period; and 875 (27.27%) were in poverty two-thirds or more of the period. A longer poverty duration was associated with lower subsequent CMMSE scores with a dose-response relationship (one-third vs never in poverty: β = -0.98; 95% confidence interval -1.61 to -0.35; two-thirds or more vs never in poverty: β = -1.55; 95% confidence interval -2.29 to -0.81). However, a longer duration of poverty was associated with a slower rate of CMMSE score decline over time from 2011 to 2018.

CONCLUSION

These findings provide valuable evidence for the role of cumulative late-life poverty in relation to cognitive health among older adults in a rapidly urbanizing and aging middle-income country. Our findings may support a compensation hypothesis for cognitive reserve in this setting.

Associations of Future Cognitive Decline with Sexual Satisfaction among Married Older Adults

Objectives: This study sought to explore changes in longitudinal cognitive status in relation to baseline measures of intimacy and sexuality in cognitively intact, married older adults.Methods: Baseline intimacy and sexuality survey data from 155, cognitively intact, married, older adults were collected using a novel survey instrument that explored the domains of: 1) romance with one's partner, 2) sexual satisfaction, 3) beliefs about sexuality, and 4) social support and emotional intimacy. These data were analyzed in relation to change in cognitive status over a 10-year follow-up period using binary logistic regression modeling. Exploratory factor analysis was used to assess the shared variance of survey items attributable to intimacy and sexuality without specification of an a priori hypothesis regarding the association of intimacy and sexuality with future change in cognitive status.Results: Over the 10-year study period, 33.5% (n = 52) of individuals developed cognitive impairment. Participants with greater sexual satisfaction scores at baseline were statistically less likely to convert from cognitively intact to mild cognitive impairment or dementia in the future (p = .01). The domains of romance with one's partner, beliefs about sexuality, and social support/emotional intimacy were not predictive of future longitudinal changes in cognitive status.Conclusions: Sexual satisfaction is associated with longitudinal cognitive outcomes in cognitively intact, married, older adults.Clinical implications: Clinicians should routinely assess for sexual satisfaction among older adults and refer to appropriate providers, such as couples or sex therapists, when appropriate.

Early Child-Parent Relationship Quality and Cognitive Function in Older Rural Chinese Adults: The Mediating Role of Educational Attainment

Objectives: Framed within a life course perspective and cognitive reserve theory, this study examined the mediating role of educational attainment for the association between child-parent relationships during childhood and cognitive function among older adults in rural China. Methods: Data were obtained from three waves of the China Health and Retirement Longitudinal Study (N = 9809). We employed latent growth curve modeling to test the association among early child-parent relationship quality, educational attainment, and cognitive function in later life. Results: Early child-mother relationship quality was associated with the level and change in cognitive function. Early child-father relationship quality was only related to baseline cognitive function. Educational attainment mediated the relationship between early child-parent relationship quality with mothers and fathers and cognitive function. Discussion: Parental relationship experience in childhood was one distal factor related to cognitive function among older adults. The findings supported the long-term impacts of childhood conditions for later life health consequences.

The Moderating Role of Education on the Relationship Between Perceived Stereotype Threat and False Memory in Aging

Studies regularly show that an age-based stereotype threat impairs older adults' performance on memory tasks. Results regarding stereotype threat effects on false memories are less clear. Some studies suggest that education may moderate the relationship between an age-related stereotype threat and episodic memory performance in older adults. The present study aimed at examining the moderating role of education on the relationship between perceived stereotype threat (PST) and false memories in older adults. With this aim, 82 adults between 60 and 70 years of age performed a Deese-Roediger-McDermott (DRM) task followed by a free recall test and completed questionnaires assessing both their perception of an age-based stereotype threat and their education level. Regression analyses showed no effect of PST on the production of critical lures. However, as was expected, our results showed that in higher educated older adults, as the perception of stereotype increases, the production of critical lures increases. These results confirm the moderating role of education and highlight its key role in the relationship between the age-based stereotype threat and older adults' susceptibility to false memories.

Incidence of Mild Cognitive Impairment, Conversion to Probable Dementia, and Mortality

BACKGROUND

Few studies have jointly estimated incidence of MCI, conversion to probable dementia, and mortality in a nationally representatie sample.

METHODS

We used data from six waves of the National Health and Aging Trends Study (2011-2016). Multivariable-adjusted multi-state survival models (MSMs) were used to model incidence upon accounting for misclassification.

RESULTS

A total of 6,078 eligible NHATS participants were included (average age: 77.49 ± 7.79 years; 58.42% females; 68.99% non-Hispanic white). The incidence of MCI was estimated to be 41.0 [35.5, 47.3]/1,000 person-years (PY). Participants converted to probable dementia at a high rate of 241.3 [189.6, 307.0]/1,000 PY, though a small number also reverted from MCI to cognitively normal. Education was associated with lower incidence of MCI and conversion to probable dementia, but increased mortality in those with MCI. There were also substantial racial and ethnic disparities in the incidence of MCI and dementia.

CONCLUSIONS

Our results underscore the relatively common incidence of and conversions between MCI and dementia in community-dwelling older Americans and uncover the beneficial impact of education to withstand cognitive impairment before death.

APOE E2/E2 Is Associated with Slower Rate of Cognitive Decline with Age

BACKGROUND

The E4 allele of the APOE gene is known to be associated with cognitive impairment. However, a limited number of studies have examined the association between the E2 allele and longitudinal changes of cognitive function.

OBJECTIVE

To determine whether rates of cognitive change differ in carriers of the APOE E2 allele compared to other genotypes.

METHODS

We conducted a secondary analysis of data from two ongoing longitudinal cohort studies, the Long Life Family Study (LLFS) and New England Centenarian Study (NECS). We included participants who had APOE genotyping data, data from longitudinal administrations of the Telephone Interview for Cognitive Status (TICS), and age, sex, and education available. We assessed whether cognitive change as measured by rate of decline in TICS score differed among people with different APOE genotypes. We used a hierarchical mixed effect model with APOE genotypes, their interactions with age, and potential confounders.

RESULTS

After adjusting for sex and education, in carriers of the common E3/E3 genotype, TICS score decreased by 0.15 points per year of age. In those with the E2/E2 genotype, TICS score decreased by 0.05 points per year of age, a significantly slower rate of decline (p = 0.017). We observed no protective effect of the E2/E3 genotype on cognitive decline.

CONCLUSION

These results suggest a protective effect of the E2/E2 genotype on a measure of global cognitive function.

Overcoming the COVID-19 Pandemic for Dementia Research: Engaging Rural, Older, Racially and Ethnically Diverse Church Attendees in Remote Recruitment, Intervention and Assessment

BACKGROUND

Access to cognitive screening in rural underserved communities is limited and was further diminished during the COVID-19 pandemic. We examined whether a telephone-based cognitive screening intervention would be effective in increasing ADRD knowledge, detecting the need for further cognitive evaluation, and making and tracking the results of referrals.

METHOD

Using a dependent t-test design, older, largely African American and Afro-Caribbean participants completed a brief educational intervention, pre/post AD knowledge measure, and cognitive screening.

RESULTS

Sixty of 85 eligible individuals consented. Seventy-percent of the sample self-reported as African American, Haitian Creole, or Hispanic, and 75% were female, with an average age of 70. AD knowledge pre-post scores improved significantly (t (49) = -3.4, p < .001). Of the 11 referred after positive cognitive screening, 72% completed follow-up with their provider. Five were newly diagnosed with dementia. Three reported no change in diagnosis or treatment. Ninety-percent consented to enrolling in a registry for future research.

CONCLUSION

Remote engagement is feasible for recruiting, educating, and conducting cognitive screening with rural older adults during a pandemic.

The Characteristics of Social Network Structure in Later Life in Relation to Incidence of Mild Cognitive Impairment and Conversion to Probable Dementia

BACKGROUND

Larger, more active social networks are estimated to be associated with lower risks of cognitive decline. However, roles of various social relationships in a broad social network in protecting against cognitive decline remain to be elucidated.

OBJECTIVE

We aimed to investigate how social roles within a social network and number of social network members are associated with cognitive decline.

METHODS

Six waves of National Health and Aging Trends Study (2011-2016, NHATS) were utilized to examine the development of mild cognitive impairment (MCI) and probable dementia determined using validated criteria. Multivariable-adjusted multi-state survival models were used to model incidences and transitions, jointly with misclassification errors.

RESULTS

A total of 6,078 eligible NHATS participants were included (average age: 77.49±7.79 years; female: 58.42%; non-Hispanic white: 68.99%). Multivariable-adjusted analyses revealed that having more social network members was associated with lower hazards of conversion from MCI to probable dementia (adjusted Hazard Ratio; aHR = 0.82; 95%confidence intervals; 95%CI = [0.67-0.99]), meanwhile having at least one college-educated family member within a social network was associated with lower incidence of probable dementia (aHR = 0.37 [0.26-0.51]). Having at least one friend within a social network was associated with a lower hazard of incidence of probable dementia (aHR = 0.48 [0.33-0.71]), but a higher risk of mortality in the MCI group (aHR = 2.58 [1.47-4.51]).

CONCLUSION

Having more social network members, having at least one friend, and having at least one college-educated family member within a social network, were associated with lower risks of incidence of dementia or conversion from MCI to dementia.

Increased variability in reaction time is associated with amyloid beta pathology at age 70

INTRODUCTION

We investigated whether life-course factors and neuroimaging biomarkers of Alzheimer's disease pathology predict reaction time (RT) performance in older adults.

METHODS

Insight 46 study participants, all born in the same week in 1946 (n = 501; ages at assessment = 69 to 71 years), completed a 2-choice RT task and amyloid beta (Aβ) positron emission tomography and MR imaging. We tested for associations between task outcomes (RT; error rate; intra-individual variability in RT) and life-course predictors including childhood cognitive ability and education. In a subsample of 406 cognitively normal participants, we investigated associations between task outcomes and biomarkers including Aβ-positivity.

RESULTS

Cognitively normal Aβ-positive participants had 10% more variable RTs than Aβ-negative participants, despite having similar mean RTs. Childhood cognitive ability and education independently predicted task performance.

DISCUSSION

This study provides novel evidence that Aβ pathology is associated with poorer consistency of RT in cognitively normal older adults, at an age when dementia prevalence is still very low.

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.

Environmental and Cognitive Enrichment in Childhood as Protective Factors in the Adult and Aging Brain

Some recent studies have highlighted a link between a favorable childhood environment and the strengthening of neuronal resilience against the changes that occur in natural aging neurodegenerative disease. Many works have assessed the factors – both internal and external – that can contribute to delay the phenotype of an ongoing neurodegenerative brain pathology. At the crossroads of genetic, environmental and lifestyle factors, these relationships are unified by the concept of cognitive reserve (CR). This review focuses on the protective effects of maintaining this CR through the cognitive aging process, and emphasizes the most essential time in life for the development and strengthening of this CR. The in-depth study of this research shows that early stimulation with regard to social and sensory interactions, contributes to the proper development of cognitive, affective and psychosocial capacities. Childhood thus appears to be the most active phase in the development of CR, and as such we hypothesize that this constitutes the first essential period of primary prevention of pathological aging and loss of cognitive capacities. If this hypothesis is correct, early stimulation of the environment would therefore be considered as a true primary prevention and a public health issue. The earlier identification of neurodevelopmental disorders, which can affect personal and professional development across the lifespan, could therefore have longer-term impacts and provide better protection against aging.

Physical activity and cognitive function: between-person and within-person associations and moderators

In the present study, we decomposed between- and within-person effects and examined moderators of the longitudinal physical activity-cognition association. Participants (N = 1722) were drawn from the Betula study and we included four waves of data across 15 years. Bayesian multilevel modeling showed that self-reported physical activity did not predict changes in cognitive function. Physical activity positively predicted cognitive performance at baseline, and the relations were stronger for more active (compared to less active) older adults. Physical activity had a positive within-person effect on cognitive function. The within-person effect of physical activity on episodic memory recall was stronger for participants who on average engaged in less physical activity. The within-person effect on verbal fluency was stronger for participants with more education. Our results suggest that preserving cognitive functioning in old age might be more a matter of what you do in old age than reflecting what you did earlier in life.

Bidirectional Associations between Obesity and Cognitive Function in Midlife Adults: A Longitudinal Study

The links between obesity and cognition remain equivocal due to a variety of methodological limitations with current research, such as an overreliance on body mass index (BMI) as a measure of obesity, the use of cross-sectional designs, and inadequate specification over the domains of cognitive function to be examined. To address these issues, we used data from the Cognitive Project of the National Survey of Midlife Development in the United States, a large-scale, longitudinal dataset on non-institutionalized midlife adults (N = 2652), which enabled us to examine the long-term bidirectional relations between obesity and two latent factors of cognition-executive function and episodic memory-while controlling for potential confounds. Results showed that, over a span of nine years, an increase in obesity in Time 1 is associated with a decline in episodic memory in Time 2 (but not executive function), while an increase in executive function in Time 1 (but not episodic memory) is associated with a reduction in obesity in Time 2. These results were elucidated when obesity was indexed with waist-to-hip ratio but not with BMI. Our findings highlight important directions for further research, in particular the use of more valid obesity indices and a greater focus on the bidirectional effects between obesity and cognition.

Different durations of cognitive stimulation therapy for Alzheimer's disease: a systematic review and meta-analysis

Objective

We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the efficacy of cognitive stimulation therapy (CST) of different durations for Alzheimer’s disease (AD).

Methods

A comprehensive search was carried out in three databases. The primary outcome was Mini-Mental State Examination (MMSE) score. We conducted a meta-analysis with Review Manager, version 5.3 and assessed the methodological quality of the included studies using the Cochrane Collaboration Recommendations assessment tool.

Results

Treatment effects from the meta-analysis showed that CST plus acetylcholinesterase inhibitors (ChEIs) was better than the control assessed by MMSE. In addition, the meta-analysis indicated that long-term CST was better than short-term or maintenance CST.

Conclusion

Our study confirmed that the combination of CST and drug treatment for AD is effective in AD, regardless of whether short-term CST, maintenance CST, or long-term CST is used. The long-term CST appears to be more effective.