State-Level Indicators of Childhood Educational Quality and Incident Dementia in Older Black and White Adults

Introducing social determinants of health to the Alzheimer's Disease Research Center network: Development and implementation in the Uniform Data Set

The Alzheimer's Disease Research Centers (ADRCs) consortium represents a critical locus of research on Alzheimer's disease and related disorders (ADRD) prevention, diagnosis, and intervention. Through the National Alzheimer's Coordinating Center's (NACC) standardized protocol, the Uniform Data Set (UDS), ADRCs have collected rich, harmonizable clinical and cognitive data. However, the collection of social data has been sparse and Center specific, constraining ADRD science that addresses research priorities on social determinants of health (SDOH) and health equity. Capitalizing on the transition to a revised UDS version 4, an interdisciplinary committee representing 10 ADRCs reviewed the literature and instrumentation, ultimately creating a brief module covering multiple domains and levels of exposure required for mechanistic studies of SDOH and brain health. This article offers rationale, empirical support, and guidance for using the selected constructs: transportation security, financial security, social connectedness, health care experiences, and discrimination, as well as recommendations for next steps that each ADRC can take to maximize local and field-level progress. HIGHLIGHTS: Social determinants of health (SDOH) play a role in Alzheimer's disease and related dementias (ADRD) risk, diagnosis, care, and research participation. A new module adds SDOH to a revised Uniform Data Set (UDS) for the Alzheimer's Disease Research Center (ADRC) consortium. UDS SDOH include transportation, socioeconomic status, social relationships, health care, and discrimination. We provide evidence for causal SDOH associations with ADRD and guidelines for use. We include recommendations for next steps and expanding the impact of the SDOH module.

Pathways to Racial/Ethnic Inequalities in Dementia

Individuals from minoritized racial/ethnic groups face a disproportionate burden of Alzheimer's disease and related dementias. This health inequality reflects structural racism, which creates and sustains racial differences in social determinants of health, including education access and quality, economic stability, social and community context, neighborhood and built environment, and health care access and quality. Thus, understanding pathways that lead to dementia inequalities requires addressing individual- and system-level factors. This article summarizes evidence linking each social determinant of health to racial/ethnic inequalities in dementia, emphasizing upstream factors and mechanisms as potential levels of intervention. The importance of resilience in marginalized groups as well as critical research considerations for dementia inequalities are also discussed. Future directions highlight the need to understand the common and unique mechanisms driving inequalities across minoritized groups, where research is lacking.

Incidence of Frailty, Dementia, and Disability Among Community-Living Older Americans According to County-Level Disadvantage

BACKGROUND

County-level contextual disadvantage is a novel social determinant of health (SDOH) for older persons. No prior study has evaluated the national incidence of geriatric conditions according to county-level contextual disadvantage among older persons. Our objective was to estimate the incidence of frailty, probable dementia, and disability over a 5-year period on the basis of county-level contextual disadvantage among community-living older Americans.

METHODS

This prospective, nationally representative longitudinal study used data from the 2015 cohort of the National Health and Aging Trends Study (NHATS), linked to various publicly available, geographically based contextual datasets. County-level disadvantage was assessed using the Geriatric Index of County-Level Multi-Dimensional Contextual Disadvantage (GERi-County), which included nine contextual indicators from these linked datasets. Data on frailty, probable dementia, and activities of daily living (ADL) disability were obtained from the NHATS annual assessments (2015-2020).

RESULTS

Totally 7499 participants were included in the analysis, representing 40,728,543 community-living older Americans. The 5-year incidence rates per 1000 person-years were significantly higher in the disadvantaged compared to the non-disadvantaged counties: 52.8 (95% confidence interval (CI), 41.6-64.0) versus 40.3 (95% CI, 37.2-43.3) for frailty; 29.9 (95% CI, 25.4-34.3) versus 21.2 (95% CI, 19.0-23.4) for probable dementia; and 78.1 (95% CI, 70.2-86.0) versus 62.5 (95% CI, 58.2-66.8) for ADL disability. For participants who lived versus did not live in disadvantaged counties, the age- and sex-adjusted HRs were 1.38 (95% CI, 1.08-1.75) for frailty, 1.53 (95% CI, 1.25-1.86) for probable dementia, and 1.30 (95% CI, 1.13-1.49) for ADL disability.

CONCLUSIONS

Community-living older Americans who reside in disadvantaged counties have a higher incidence of frailty, probable dementia, and ADL disability over a 5-year follow-up period compared to their non-disadvantaged counterparts. Findings underscore the vital, underappreciated role that county-level social contextual disadvantage plays on clinically meaningful outcomes in older persons in the U.S.

Invited commentary: improving spatial exposure data for everyone-life-course social context and ascertaining residential history

Measuring age-specific, contextual exposures is crucial for life-course epidemiology research. Longitudinal residential data offer a "golden ticket" to cumulative exposure metrics and can enhance our understanding of health disparities. Residential history can be linked to myriad spatiotemporal databases to characterize environmental, socioeconomic, and policy contexts that a person has experienced throughout life. However, obtaining accurate residential history is challenging in the United States due to the limitations of administrative registries and self-reports. In a recent article, Xu et al (Am J Epidemiol. 2024;193(2):348-359) detailed an approach to linking residential history sourced from LexisNexis Accurint to a Wisconsin-based research cohort, offering insights into challenges with collection of residential history data. Researchers must analyze the magnitude of selection and misclassification biases inherent to ascertaining residential history from cohort data. A life-course framework can provide insights into why the frequency and distance of moves is patterned by age, birth cohort, racial/ethnic identity, socioeconomic status, and urbanicity. Historical and contemporary migration patterns of marginalized people seeking economic and political opportunities must guide interpretations of residential history data. In this commentary, we outline methodological priorities for use of residential history in health disparities research, including contextualizing residential history data with determinants of residential moves, triangulating spatial exposure assessment methods, and transparently quantifying measurement error.

Novel indices of state- and county-level social disadvantage in older Americans and disparities in mortality

Studying and defining social contextual disadvantage in community-living older persons is vitally important, yet no composite indices of social disadvantage have been developed and validated specifically for the geriatric population. The current study aims to create two novel composite indices representing state- and county-level social contextual disadvantage in older (≥65 years) persons in the United States (US), and to evaluate whether disparities in mortality exist between index-defined disadvantaged and non-disadvantaged groups. Publicly-available state- and county-level (2006-2014) contextual factors from all 50 US states and 3132 counties were used to create indices of social contextual disadvantage. Associations of disadvantage-status with mortality (2010-2019) were assessed by negative binomial models. We found mortality rates were significantly higher in index-defined disadvantaged states/counties compared with non-disadvantaged ones for 2010-2015 and 2014-2019. For both periods, compared with non-disadvantaged states, the disadvantaged states had at least 11% increased mortality risk. At the county-level, the disadvantaged counties had an approximately 10% increased mortality risk. The findings suggest that the two indices of state- and county-level contextual disadvantage in older persons may serve as useful tools for identifying place-based disadvantaged populations of older Americans and as multidimensional factors driving mortality disparities. State- and county-level social contextual disadvantage should be considered when formulating public health policies and interventions aimed at reducing health disparities.

Education and midlife cognitive functioning: Evidence from the High School and Beyond cohort

INTRODUCTION

Educational attainment is associated with midlife cognitive functioning. However, degree attainment is the culmination of complex and unequal processes involving students' backgrounds, the opportunities that schools provide them, and their performance within those schools─all of which may also shape midlife cognition. What do educational gradients in midlife cognition look like using a richer conceptualization and measures of "education?"

METHODS

We use data from High School and Beyond (HS&B:80)─a large, nationally representative sample of Americans followed from high school through age ∼60─to assess the role of education in stratifying midlife cognition.

RESULTS

High schools' academic and socioeconomic environments predict midlife cognition primarily through their associations with their students' academic performance. Student academic performance strongly predicts midlife cognition, partially through its association with degree attainment.

DISCUSSION

Inequalities in educational opportunities and in students' performance in schools shape midlife cognition─even among students with the same attained degrees.

HIGHLIGHTS

Degree attainment predicts midlife cognitive functioning, but a large portion of that association is accounted for by students' high school academic performance as measured by test scores, grades, and course completion. High school contexts and learning opportunities predict midlife cognition mainly because they play a role in shaping students' academic performance. Understanding the potential benefits of education for later-life cognitive functioning requires attention to broader schooling processes and to students' academic performance beyond degree attainment.

Racial/Ethnic Differences in Neuropsychological Test Performance in Frontotemporal Degeneration

Racial disparities in neuropsychological test performance are well documented in Alzheimer's Disease (AD) but have received little attention in frontotemporal degeneration (FTD). Identification of potential disparities in neuropsychological performance is critical to identify ways to improve inclusivity in clinical research and care of representative FTD populations. We evaluated disparities in neuropsychological performance among individuals with clinically diagnosed FTD (behavioral variant FTD [bvFTD] or primary progressive aphasia [PPA]) using data from the National Alzheimer's Coordinating Center (NACC) collected between September 2005 and November 2023. Only 10% of NACC FTD cases are from racially/ethnically minoritized groups. Black (n=56), Hispanic (n=77) and White (n=1301) individuals were evaluated in the cognitive domains of episodic memory, working memory, processing speed, cognitive flexibility, attention, category fluency and lexical retrieval, in addition to global cognition across Uniform Data Set versions 1 to 3. Linear regressions examined the association between racial/ethnic group and cognitive scores covarying for disease stage, age, sex, and education. After adjusting for age, sex, and education using NACC established normative correction, binary logistic regression examined group differences in the proportion of participants classified as impaired (<=-1.5 normative z-score) for each cognitive test. Minoritized individuals, on average, had lower scores and/or greater likelihood of impairment (odds ratio; OR) on measures of global cognition (Black: β = -3.63; OR = 2.74; Hispanic: β = -2.50), lexical retrieval (Black: β = -4.31; OR = 3.28; Hispanic: β = -2.90; OR = 3.81), processing speed (Black: β = 26.80; OR = 4.07; Hispanic: β = 21.31; OR = 2.37), cognitive flexibility (Black: β = 46.65; OR = 3.35), attention (Hispanic: β = -0.39), working memory (Black: β = -0.79; Hispanic: β = -0.42), episodic memory (Hispanic: β = -1.67), and category fluency (Hispanic: β = -1.28). We did not identify any neuropsychological tests where White individuals performed worse than minoritized individuals. These findings indicate racial/ethnic differences in neuropsychological test performance on measures of global cognition, executive function, and lexical retrieval. Critically, these tests are used in diagnosis and monitoring of FTD. Future efforts must focus on increasing research participation in underrepresented populations with FTD to support the diverse needs of individuals, and an understanding of social determinants of health in FTD to evaluate potential sources of the observed differences across racial and ethnic groups.

Exposure to School Racial Segregation and Late-Life Cognitive Outcomes

Importance

Disparities in cognition, including dementia occurrence, persist between non-Hispanic Black (hereinafter, Black) and non-Hispanic White (hereinafter, White) older adults, and are possibly influenced by early educational differences stemming from structural racism. However, the association between school racial segregation and later-life cognition remains underexplored.

Objective

To investigate the association between childhood contextual exposure to school racial segregation and cognitive outcomes in later life.

Design, Setting, and Participants

This cross-sectional study examined a nationally representative sample of US older adults from the Health and Retirement Study. Both restricted childhood residence data and publicly available cognitive assessment data (survey years 1995-2018) were used for Black and White participants aged 65 years and older. Data analyses were performed from March 2, 2023, to October 22, 2024.

Exposures

State-level Black and White dissimilarity index for public elementary schools in the late 1960s (range, 0-100) was used to measure school segregation. States were categorized into high segregation (≥83.6) and low segregation (<83.6) based on the top quintile.

Main Outcomes and Measures

Cognitive scores, cognitive impairment, and dementia were assessed using the Telephone Interview for Cognitive Status and proxy assessment. Multilevel regression analyses were conducted stratified by race and ethnicity, adjusting for sociodemographic covariates. Potential early-life and midlife mediators, including educational attainment, were assessed.

Results

The study sample included 3566 Black (16 104 observations) and 17 555 White (90 874 observations) participants. The mean (SD) age of the sample was 75.6 (7.5) years, and 62 187 (58.1%) were female. Participants exposed to high vs low segregation exhibited lower cognitive scores (13.6 vs 14.5) and a higher prevalence of cognitive impairment (37.0% vs 28.0%) and dementia (14.1% vs 9.3%). Multilevel analyses revealed a significant negative association between school segregation and later-life cognitive outcomes among Black participants, but not among White participants, after adjusting for covariates. Potential mediators across the life course, including educational attainment, explained 57.6% to 72.6% of the association, yet the findings were significant among Black participants for all outcomes. In the model including all mediators and covariates, Black participants exposed to high segregation exhibited significantly lower cognitive scores (coefficient, -0.26; 95% CI, -0.43 to -0.09) and a higher likelihood of cognitive impairment (adjusted odds ratio [AOR], 1.35; 95% CI, 1.12-1.63) and dementia (AOR, 1.26; 95% CI, 1.03-1.54).

Conclusions and Relevance

This cross-sectional study of Black and White older individuals found that childhood exposure to school segregation was associated with late-life cognition among the Black population. Given the increasing amount of school segregation in the US, educational policies aimed at reducing segregation are needed to address health inequities. Clinicians may leverage patients' early-life educational circumstances to promote screening, prevention, and management of cognitive disorders.

Predictive value and weight of factors associated with cognitive performance in Hispanics/Latinos enrolled in the Health and Aging Brain Study: Health Disparities

INTRODUCTION

In this analysis of cognitively unimpaired (CU) Hispanic participants from the Health and Aging Brain Study: Health Disparities (HABS-HD), we aimed to identify the main predictor factors for cognitive performance and their relative importance (weight).

METHODS

The HABS-HD is a community-based longitudinal cohort study. Data from 952 CU Hispanics, enrolled from 2017 to February 2024, were analyzed. Random forest, an assembly learning method based on decision trees, was used to cross-sectionally forecast the predictive value of 42 risk factors (4 demographic variables, 4 socioeconomic variables, 6 psychosocial variables, 17 health variables, and 11 plasma and magnetic resonance imaging biomarkers) together, and the weighting of each factor for different cognitive domains (global cognition, memory, language, executive function, attention, and processing speed).

RESULTS

Participants included in the analyses had a mean age of 61.3 years (9.14), 69.4% were female, and had a mean of 10.52 (4.61) years of education. Income, glucose levels, plasma amyloid beta (Aβ)42, total tau, and neurofilament light chain were in the top 10 predictors in six cognitive domains. Age, education years, Penn State Worry Questionnaire, body mass index, and C-reactive protein were the main predictors in four cognitive domains, while plasma Aβ40 was in the top 10 list for five cognitive domains.

DISCUSSION

Results support the notion that cognitive performance depends on interactions among social, economic, biological, and functional factors. The effects of factors together, and the weight of each factor in various cognitive domains may be different in Hispanics. More studies comparing different ethnic groups are necessary to help in the development of tailored interventions to prevent cognitive decline.

Highlights

Numerous factors have been associated with cognitive decline and dementia.Research on these factors has relied on a meta-analysis of their individual association with cognition, consolidating data from different non-Hispanic White populations.Hispanics are the largest minority group in the United States, and only a few studies have analyzed the overall impact of these factors together, and their individual relative effect in different cognitive domains.We found that cognitive performance in Hispanics may be a result of interactions among social, economic, biological, and functional factors.

State Schooling Policies and Cognitive Performance Trajectories: A Natural Experiment in a National US Cohort of Black and White Adults

BACKGROUND

Education is strongly associated with cognitive outcomes at older ages, yet the extent to which these associations reflect causal effects remains uncertain due to potential confounding.

METHODS

Leveraging changes in historical measures of state-level education policies as natural experiments, we estimated the effects of educational attainment on cognitive performance over 10 years in 20,248 non-Hispanic Black and non-Hispanic White participants, aged 45+ in the Reasons for Geographic and Racial Disparities in Stroke cohort (2003-2020) by (1) using state- and year-specific compulsory schooling laws, school-term length, attendance rate, and student-teacher ratio policies to predict educational attainment for US Census microsample data from 1980 and 1990, and (2) applying policy-predicted years of education (PPYEd) to predict memory, verbal fluency, and a cognitive composite. We estimated overall and race- and sex-specific effects of PPYEd on level and change in each cognitive outcome using random intercept and slope models, adjusting for age, year of first cognitive assessment, and indicators for state of residence at age 6.

RESULTS

Each year of PPYEd was associated with higher baseline cognition (0.11 standard deviation [SD] increase in composite measure for each year of PPYEd, 95% confidence interval [CI] = 0.07, 0.15). Subanalyses focusing on individual cognitive domains estimate the largest effects of PPYEd on memory. PPYEd was not associated with the rate of change in cognitive scores. Estimates were similar across Black and White participants and across sex.

CONCLUSIONS

Historical policies shaping educational attainment are associated with better later-life memory, a major determinant of dementia risk.

Brain health equity and the influence of social determinants across the life cycle

Social determinants of health are social, economic and environmental factors known to influence health and development of infants, children and adults. Advancing equity in brain health relies upon interdisciplinary collaboration and recognition of the impact of social determinants on brain health through the lifespan and across generations. Critical periods of fetal, infant and early childhood development encompass intrinsic genetic and extrinsic environmental influences with complex gene-environment interactions. This review discusses the influence of social determinants on the continuum of brain health from preconception and pregnancy health, through fetal, infant and childhood neurodevelopment into adulthood. Opportunities for intervention to address the social determinants of brain health across the life cycle are highlighted.

Factors Affecting Resilience and Prevention of Alzheimer's Disease and Related Dementias

Alzheimer's disease (AD) is a devastating, age-associated neurodegenerative disorder and the most common cause of dementia. The clinical continuum of AD spans from preclinical disease to subjective cognitive decline, mild cognitive impairment, and dementia stages (mild, moderate, and severe). Neuropathologically, AD is defined by the accumulation of amyloid β (Aβ) into extracellular plaques in the brain parenchyma and in the cerebral vasculature, and by abnormally phosphorylated tau that accumulates intraneuronally forming neurofibrillary tangles (NFTs). Development of treatment approaches that prevent or even reduce the cognitive decline because of AD has been slow compared to other major causes of death. Recently, the United States Food and Drug Administration gave full approval to 2 different Aβ-targeting monoclonal antibodies. However, this breakthrough disease modifying approach only applies to a limited subset of patients in the AD continuum and there are stringent eligibility criteria. Furthermore, these approaches do not prevent progression of disease, because other AD-related pathologies, such as NFTs, are not directly targeted. A non-mutually exclusive alternative is to address lifestyle interventions that can help reduce the risk of AD and AD-related dementias (ADRD). It is estimated that addressing such modifiable risk factors could potentially delay up to 40% of AD/ADRD cases. In this review, we discuss some of the many modifiable risk factors that may be associated with prevention of AD/ADRD and/or increasing brain resilience, as well as other factors that may interact with these modifiable risk factors to influence AD/ADRD progression. [Color figure can be viewed at www.annalsofneurology.org] ANN NEUROL 2024;96:633-649.

State-Level Education Quality and Trajectories of Cognitive Function by Race and Educational Attainment

Policy Points Education-cognition research overlooks the role of education quality in shaping cognitive function at midlife and older ages, even though quality may be more responsive to federal and state investment in public schooling than attainment. For older US adults who attended school during the early to mid-20th century, the quality of US education improved considerably as federal and state investment increased. Ensuring access to high-quality primary and secondary education may protect against poor cognitive function at midlife and older ages, particularly among Black Americans and persons who complete less education. It may also play an important role in reducing health inequities.

CONTEXT

Although educational attainment is consistently associated with better cognitive function among older adults, we know little about how education quality is related to cognitive function. This is a key gap in the literature given that the quality of US education improved considerably during the early to mid-20th century as state and federal investment increased. We posit that growing up in states with higher-quality education systems may protect against poor cognitive function, particularly among Black adults and adults who completed fewer years of school.

METHODS

We used prospective data on cognitive function from the Health and Retirement Study linked to historical data on state investment in public schools, restricting our sample to non-Hispanic White and Black adults born between 1914 and 1959 (19,096 White adults and 4,625 Black adults). Using race-stratified linear mixed models, we considered if state-level education quality was associated with level and decline in cognitive function and if these patterns differed by years of schooling and race.

FINDINGS

Residing in states with higher-resourced education systems during childhood was associated with better cognitive function, particularly among those who completed less than 12 years of schooling, regardless of race. For White adults, higher-resourced state education systems were associated with higher scores of total cognitive function and episodic memory, but there were diminishing returns as resources increased to very high levels. For Black adults, the relationship between state education resources and cognitive function varied by age with positive associations in midlife and generally null or negative associations at the oldest ages.

CONCLUSIONS

Federal and state investment in public schools may provide students with opportunities to develop important cognitive resources during schooling that translate into better cognitive function in later life, especially among marginalized populations.

Assessing Risk Factors for Cognitive Decline Using Electronic Health Record Data: A Scoping Review

Background

The data and information contained within electronic health records (EHR) provide a rich, diverse, longitudinal view of real-world patient histories, offering valuable opportunities to study antecedent risk factors for cognitive decline. However, the extent to which such records' data have been utilized to elucidate the risk factors of cognitive decline remains unclear.

Methods

A scoping review was conducted following the PRISMA guideline, examining articles published between January 2010 and April 2023, from PubMed, Web of Science, and CINAHL. Inclusion criteria focused on studies using EHR to investigate risk factors for cognitive decline. Each article was screened by at least two reviewers. Data elements were manually extracted based on a predefined schema. The studied risk factors were classified into categories, and a research gap was identified.

Results

From 1,593 articles identified, 80 were selected. The majority (87.5%) were retrospective cohort studies, with 66.3% using datasets of over 10,000 patients, predominantly from the US or UK. Analysis showed that 48.8% of studies addressed medical conditions, 31.3% focused on medical interventions, and 17.5% on lifestyle, socioeconomic status, and environmental factors. Most studies on medical conditions were linked to an increased risk of cognitive decline, whereas medical interventions addressing these conditions often reduced the risk.

Conclusions

EHR data significantly enhanced our understanding of medical conditions, interventions, lifestyle, socioeconomic status, and environmental factors related to the risk of cognitive decline.

Early-Life Circumstances and Racial Disparities in Cognition Among Older Adults in the US

Importance

Given the critical role of neurocognitive development in early life, understanding the association between early-life circumstances and racial disparities in cognition has important implications.

Objective

To assess whether racial differences in early-life circumstances are collectively and individually associated with racial disparities in late-life cognition among older adults in the US.

Design, Setting, and Participants

This cross-sectional study used comprehensive life history data from the Health and Retirement Study, a nationally representative survey of US adults 50 years or older. Data analyses were performed from August 9, 2022, to January 20, 2024.

Main Outcomes and Measures

Racial differences in early-life circumstances and racial disparities in late-life cognition were investigated using a Blinder-Oaxaca decomposition regression model. Cognitive outcomes, including cognitive score and cognitive impairment, were evaluated using the Telephone Interview for Cognitive Status. Early-life educational experiences were primary explanatory variables; early-life cohort, regional, financial, health, trauma, family relationship factors, and educational attainment were additional explanatory variables; demographic and genetic factors were covariates.

Results

The study sample comprised 9015 participants; 1634 non-Hispanic Black (hereafter, Black) individuals (18.1%) and 7381 non-Hispanic White (hereafter, White) individuals (81.9%). Among Black participants, the mean (SD) age was 69.2 (9.2) years and 1094 (67.0%) were women. Among White participants, the mean (SD) age was 73.2 (10.1) years and 4410 (59.7%) were women. Cognitive scores (scale, 0-27) were significantly lower among Black participants (13.5 [95% CI, 13.3-13.7] points) than among White participants (15.8 [95% CI, 15.7-15.9] points), while the prevalence of cognitive impairment (cognitive score <12) was significantly higher among Black participants (33.6 [95% CI, 31.3-35.9] percentage points [ppt]) than among White participants (16.4 [95% CI, 15.6-17.2] ppt). Substantial racial differences were observed in early-life circumstances. Overall, differences in early-life circumstances were associated with 61.5% of the racial disparities in cognitive score (1.4 [95% CI, 0.88-2.0] points), and 82.3% of the racial disparities in cognitive impairment (14.2 [95% CI, 8.8-19.5] ppt), respectively. In multivariable analyses, early-life educational experiences were associated with 35.2% of the disparities in cognitive score and 48.6% in cognitive impairment. Notably, school racial segregation (all segregated schooling before college) was associated with 28.8% to 39.7% of the racial disparities in cognition. These findings were consistent in a series of sensitivity analyses.

Conclusions and Relevance

The findings of this cross-sectional study suggest that less favorable early-life circumstances are associated with clinically meaningful racial disparities in late-life cognition. Policies that improve educational equity have the potential to reduce racial disparities in cognition in older ages. Clinicians may leverage early-life circumstances to promote the screening, prevention, and interventions of cognitive impairment more efficiently, thereby promoting health equity.

Association of Childhood Exposure to School Racial Segregation with Late-Life Cognitive Outcomes among Older Americans

IMPORTANCE

Disparities in cognition, including dementia occurrence, persist between White and Black older adults, and are possibly influenced by early educational differences stemming from structural racism. However, the relationship between school racial segregation and later-life cognition remains underexplored.

OBJECTIVE

To investigate the association between childhood contextual exposure to school racial segregation and cognitive outcomes in later life.

DESIGN SETTING AND PARTICIPANTS

Data from 16,625 non-Hispanic White (hereafter, White) and 3,335 non-Hispanic Black (hereafter, Black) Americans aged 65 or older were analyzed from the Health and Retirement Study.

EXPOSURES

State-level White-Black dissimilarity index for public elementary schools in the late 1960s (range: 0-100) was used to measure school segregation. States were categorized into high segregation (383.6) and low segregation (<83.6) based on the top quintile.

MAIN OUTCOMES AND MEASURES

Cognitive scores, cognitive impairment (with or without dementia), and dementia were assessed using the Telephone Interview for Cognitive Status (TICS) and proxy assessment. Multilevel regression analyses were conducted, adjusting for demographic covariates, socioeconomic status, and health factors. Stratified analyses by race were performed.

RESULTS

The mean (SD) age of participants was 78.5 (5.7) years, and 11,208 (56.2%) were female. Participants exposed to high segregation exhibited lower cognitive scores (12.6 vs. 13.6; P<0.001) and higher prevalence of cognitive impairment (50.8% vs 41.4%; P<0.001) and dementia (26.0% vs. 19.5%; P<0.001), compared to those with low segregation exposure. Multilevel analyses revealed a significant negative association between school segregation and later-life cognitive even after adjusting sequentially for potential confounders, and these associations were stronger among Black than White participants. Notably, in the fully adjusted model, Black participants exposed to high segregation displayed significantly lower cognitive scores (-0.51; 95% CI: -0.94, -0.09) and higher likelihood of cognitive impairment (adjusted Odds Ratio [aOR]: 1.45, 95% CI: 1.22, 1.72) and dementia (aOR: 1.31, 95% CI: 1.06, 1.63).

CONCLUSIONS AND RELEVANCE

Our study underscores that childhood exposure to state-level school segregation is associated with late-life cognition, especially for Black Americans. Given the rising trend of school segregation in the US, educational policies aimed at reducing segregation are crucial to address health inequities. Clinicians can leverage patients' early-life educational circumstances to promote screening, prevention, and management of cognitive disorders.

Educational Attainment and Later-Life Cognitive Function in High- and Middle-Income Countries: Evidence From the Harmonized Cognitive Assessment Protocol

OBJECTIVES

Identifying social policies that can promote cognitive health is crucial for reducing the global burden of dementia. We evaluated the importance of educational attainment for later-life cognitive function in various social and geographic settings.

METHODS

Using harmonized data for individuals aged ≥65 years from the United States Health and Retirement Study (HRS) and its international partner studies in England, Mexico, China, and India, and each study's respective Harmonized Cognitive Assessment Protocol (HCAP), we conducted a cross-national comparative study to examine the role of educational attainment in later-life cognitive function across countries (n = 14,980, 2016-2019). We used multivariable-adjusted regression to estimate associations between educational attainment and harmonized global cognitive function scores.

RESULTS

In Mexico, China, and India, the general cognitive function scores on average are approximately one standard deviation of the HRS-HCAP cognitive function score distribution lower compared to the United States and England, paralleling patterns of educational attainment across countries. In all countries, higher educational attainment was associated with progressively higher later-life cognitive function scores. Population-level differences in educational attainment explained about 50%-90% of the observed differences in cognitive function scores across countries.

DISCUSSION

The relationship between education and later-life cognitive function across social and geographic contexts underscores the crucial role of education to promote cognitive health and reduce dementia risk. Continual improvement of educational attainment in low- and middle-income settings may yield a significant pay-off in later-life cognitive health.

Deriving life-course residential histories in brain bank cohorts: A feasibility study

INTRODUCTION

The exposome is theorized to interact with biological mechanisms to influence risk for Alzheimer's disease but is not well-integrated into existing Alzheimer's Disease Research Center (ADRC) brain bank data collection.

METHODS

We apply public data tracing, an iterative, dual abstraction and validation process rooted in rigorous historic archival methods, to develop life-course residential histories for 1254 ADRC decedents.

RESULTS

The median percentage of the life course with an address is 78.1% (IQR 24.9); 56.5% of the sample has an address for at least 75% of their life course. Archivists had 89.7% agreement at the address level. This method matched current residential survey methodology 97.4% on average.

DISCUSSION

This novel method demonstrates feasibility, reproducibility, and rigor for historic data collection. To our knowledge, this is the first study to show that public data tracing methods for brain bank decedent residential history development can be used to better integrate the social exposome with biobank specimens.

HIGHLIGHTS

Public data tracing compares favorably to survey-based residential history. Public data tracing is feasible and reproducible between archivists. Archivists achieved 89.7% agreement at the address level. This method identifies residences for nearly 80% of life-years, on average. This novel method enables brain banks to add social characterizations.

Identifying the mediating role of inflammation on the relationship between socioeconomic status and Alzheimer's disease: a Mendelian randomization analysis and mediation analysis

BACKGROUND AND OBJECTIVES

Observational studies have demonstrated a significant association between socio-economic status (SES) and Alzheimer's disease (AD). Nonetheless, the precise biological mechanisms underlying this association remain unclear. Therefore, we adopted a Mendelian Randomization (MR) approach to investigate the causal relationship between SES and genetic susceptibility to AD, as well as to explore the potential mediation effects of inflammation.

METHODS

Large-scale cohorts based on publicly available genome-wide association study (GWAS) datasets from European populations were employed for conducting the MR study. The primary criterion utilized was the inverse-variance weighting (IVW) model. Heterogeneity and horizontal pleiotropy were assessed. In addition, multivariate MR (MVMR) was utilized to correct the confounders. Moreover, a two-step MR approach was used to evaluate the potential mediating effects of factors on the causal effects between SES and AD.

RESULTS

As indicated by the results of the IVW model, educational years (OR = 0.708, 95% CI 0.610-0.821, P < 0.001) and household income (OR = 0.746, 95% CI 0.566-0.982, P = 0.037) was associated with a decreased genetic susceptibility risk for AD. The univariable results showed that the causal effect of educational years on the lower risk of AD remained significant (OR = 0.643, 95% CI 0.467-0.886, P = 0.006). In addition, our findings indicated that C-reactive protein (CRP) played a role in the causal effect of educational years on AD. The proportions of mediation were - 50.08% (95% CI - 92.78; - 7.38%).

DISCUSSION

These findings provided evidence supporting the causal effect of educational attainment lower AD risk, with inflammation playing a mediating role. These findings may inform prevention strategies and interventions directed toward AD. Future studies should explore other plausible biological mechanisms.

Spouses of individuals living with mild cognitive impairment or dementia in the United States: A descriptive, population-based study

BACKGROUND

Little is known about the population of individuals who live with a spouse with cognitive impairment (CI) or dementia.

METHODS

Using the US Health and Retirement Study, 2000 to 2018, we estimated the population of adults ≥ 50 years old co-residing with a spouse with probable CI/dementia. We described their socio-demographic and health characteristics and quantified socio-demographic inequities.

RESULTS

Among community-dwelling adults ≥ 50 years old, 6% of women and 4% of men co-resided with a spouse with probable CI/dementia. Among those who were married/partnered, the prevalence of spousal dementia was greater for Black and Hispanic adults compared to their White counterparts, and for those with lower versus higher educational attainment. Among spouses, activities of daily living disability, depression, and past 2-year hospitalization was common.

DISCUSSION

Millions of older adults, disproportionately Black and Hispanic people and people with lower levels of educational attainment, live with a spouse with CI while also facing their own major health challenges.

Place of Birth and Cognition among Older Americans: Findings from the Harmonized Cognitive Assessment Protocol

Objectives

Growing evidence suggests that place of birth (PoB) and related circumstances may have long-lasting and multiplicative contributions to various later-life outcomes. However, the specific contributions to different domains of cognitive function in late life remain less understood. This study aimed to investigate the extent to which PoB contribute to a wide range of later-life cognitive outcomes.

Methods

A nationally representative sample of Americans aged 65 and older (N=3,216) from the Health and Retirement Study (HRS) Harmonized Cognitive Assessment Protocol (HCAP) was utilized. Cognitive outcomes were assessed in HCAP and linked to HRS state-level PoB data to explore the contribution of birthplace to later-life cognitive disparities. Regression-based Shapley decompositions were employed to quantify this contribution.

Results

PoB significantly contributed to all assessed cognitive outcomes including memory, executive function, language and fluency, visuospatial function, orientation, global cognitive performance, cognitive impairment and dementia. Geographic disparities in cognitive outcomes were evident, with individuals born in US southern states and foreign-born individuals performing worse than those born in other states. PoB overall accounted for 2.4-13.9% of the total variance in cognition after adjusting for age and sex. This contribution reduced by half when adjusting for a rich set of sociodemographic and health factors over the life course, but PoB still independently explained 2.0-7.1% of the total variance in cognition.

Discussion

PoB has lasting contributions to later-life cognitive health, with significant geographic disparities observed. Addressing these disparities requires promoting more equalized place-based policies, resources, and early-life environments to improve health equities over the life course.