Racial segregation and cognitive function among older adults in the United States: Findings from the REasons for Geographic and Racial Differences in Stroke (REGARDS) study

Multi-Ancestry Transcriptome-Wide Association Studies of Cognitive Function, White Matter Hyperintensity, and Alzheimer's Disease

Genetic variants increase the risk of neurocognitive disorders in later life, including vascular dementia (VaD) and Alzheimer's disease (AD), but the precise relationships between genetic risk factors and underlying disease etiologies are not well understood. Transcriptome-wide association studies (TWASs) can be leveraged to better characterize the genes and biological pathways underlying genetic influences on disease. To date, almost all existing TWASs on VaD and AD have been conducted using expression studies from individuals of a single genetic ancestry, primarily European. Using the joint likelihood-based inference framework in Multi-ancEstry TRanscriptOme-wide analysis (METRO), we leveraged gene expression data from European ancestry (EA) and African ancestry (AA) samples to identify genes associated with general cognitive function, white matter hyperintensity (WMH), and AD. Regions were fine-mapped using Fine-mapping Of CaUsal gene Sets (FOCUS). We identified 266, 23, 69, and 2 genes associated with general cognitive function, WMH, AD (using EA GWAS summary statistics), and AD (using AA GWAS), respectively (Bonferroni-corrected alpha = p < 2.9 × 10-6), some of which had been previously identified. Enrichment analysis showed that many of the identified genes were in pathways related to innate immunity, vascular dysfunction, and neuroinflammation. Further, the downregulation of ICA1L was associated with a higher WMH and with AD, indicating its potential contribution to overlapping AD and VaD neuropathology. To our knowledge, our study is the first TWAS on cognitive function and neurocognitive disorders that used expression mapping studies for multiple ancestries. This work may expand the benefits of TWASs beyond a single ancestry group and help to identify gene targets for pharmaceuticals or preventative treatments for dementia.

Racial disparities in hospitalization and neighborhood deprivation among Medicare beneficiaries

Many neighborhoods with concentrated racial and ethnic minority older adult populations experience high neighborhood disadvantage. Yet, to date, no studies have analyzed how neighborhood disadvantage affects the relationship between race and hospitalization among older adults. To fill this gap, we examined if neighborhood disadvantage moderates the relationship between race and hospitalization among older adults in the United States. Medicare claims data from 2018 on 530 962 beneficiary hospitalizations were merged with neighborhood data, and regression models assessed if the Area Deprivation Index (ADI) moderated the association between race and hospitalization. At the highest ADI score, the odds ratio (OR) for hospitalization for Black compared with White beneficiaries was the lowest (OR: 0.96; 95% CI: 0.89-1.04). At the lowest ADI score, the OR for hospitalization for Black compared with White beneficiaries was the highest (OR: 1.19; 95% CI: 1.09-1.29). When Black and White beneficiaries reside in severely deprived areas, the disparity in their outcomes is narrower. However, when they reside in areas with more advantages, White beneficiaries experience better outcomes than Black beneficiaries. Our findings have implications for practice and policy to invest resources in communities to assure health equity.

Neighborhood environment associations with cognitive function and structural brain measures in older African Americans

BACKGROUND

Since older adults spend significant time in their neighborhood environment, environmental factors such as neighborhood socioeconomic disadvantage, high racial segregation, low healthy food availability, low access to recreation, and minimal social engagement may have adverse effects on cognitive function and increase susceptibility to dementia. DNA methylation, which is associated with neighborhood characteristics as well as cognitive function and white matter hyperintensity (WMH), may act as a mediator between neighborhood characteristics and neurocognitive outcomes.

METHODS

In this study, we examined whether DNA methylation in peripheral blood leukocytes mediates the relationship between neighborhood characteristics and cognitive function (N = 542) or WMH (N = 466) in older African American (AA) participants without preliminary evidence of dementia from the Genetic Epidemiology Network of Arteriopathy (GENOA).

RESULTS

For a 1-mile buffer around a participant's residence, each additional fast food destination or unfavorable food store with alcohol per square mile was nominally associated with a 0.05 (95%CI: 0.01, 0.09) and a 0.04 (0.00, 0.08) second improvement in visual conceptual tracking score, respectively. Also, each additional alcohol drinking place per square mile was nominally associated with a 0.62 (0.05, 1.19) word increase in delayed recall score, indicating better memory function (all p < 0.05). Neighborhood characteristics were not associated with WMH. We did not find evidence that DNA methylation mediates the observed associations between neighborhood characteristics and cognitive function.

CONCLUSIONS

The presence of fast food destinations and unfavorable food stores with alcohol was associated cognitive measures, possibly due to greater social interaction provided in these venues. However, replication of these findings is necessary. Further examination of the potential pathways between the neighborhood environment and cognitive function/WMH may allow the development of potential behavioral, infrastructural, and pharmaceutical interventions to facilitate aging in place and healthy brain aging in older adults, especially in marginal populations that are most at risk.

The effects of residential segregation on cognition among U.S. older adults: a systematic review based on the social determinants of health model

OBJECTIVES

This systematic review aims to advance the understanding of the complicated effects of segregation on older adults' cognition and provide guidance for future research.

METHOD

A systematic review using the Social Determinants of Health framework to examine the relationship between segregation and cognition across the selected literature.

RESULTS

Eight papers met the criteria for inclusion. All selected studies examined the influence of living in a segregated area on older adults' cognition, covering older adults from different racial/ethnic groups. The association between segregation and cognition was found in different directions across different racial/ethnic groups. The effects can be varied depending on race/ethnicity, level of education, neighborhood socioeconomic status, or social context.

CONCLUSION

This review identified existing gaps in understanding the relationship between segregation and cognition. Future studies should carefully adopt the segregation measures, acknowledge the varying segregation experience among different racial/ethnic groups, and consider more social determinant factors in research.

Neighborhood racial income inequality and cognitive health

INTRODUCTION

Neighborhood socioeconomic status (SES) has been linked to dementia, but the distribution of SES within a neighborhood may also matter.

METHODS

Data from 460 (47% Black, 46% White) older adults from the Michigan Cognitive Aging Project were linked to census tract-level data from the National Neighborhood Data Archive (NaNDA). Neighborhood SES included two composites reflecting disadvantage and affluence. Neighborhood racial income inequality was the ratio of median incomes for White versus Black residents. Generalized estimating equations examined associations between neighborhood factors and cognitive domains.

RESULTS

Neighborhood racial income inequality was uniquely associated with worse cognitive health, and these associations did not differ by participant race. Neighborhood disadvantage was only associated with worse cognitive health among Black participants.

DISCUSSION

Both the level and racial distribution of SES within a neighborhood may be relevant for dementia risk. Racial differences in the level and impact of neighborhood SES contribute to dementia inequalities.

HIGHLIGHTS

Black participants lived in neighborhoods with lower socioeconomic status (SES) than White participants, on average. Neighborhood SES and racial income inequality were associated with worse cognition. Effects of neighborhood racial income inequality did not differ across racial groups. Effects of neighborhood SES were only evident among Black participants.

"Hang Ups, Let Downs, Bad Breaks, Setbacks": Impact of Structural Socioeconomic Racism and Resilience on Cognitive Change Over Time for Persons Racialized as Black

Introduction

Older adults racialized as Black experience higher rates of dementia than those racialized as White. Structural racism produces socioeconomic challenges, described by artist Marvin Gaye as "hang ups, let downs, bad breaks, setbacks" that likely contribute to dementia disparities. Robust dementia literature suggests socioeconomic factors may also be key resiliencies.

Methods

We linked state-level data reflecting the racialized landscape of economic opportunity across the 20th Century from the U.S. Census (1930-2010) with individual-level data on cognitive outcomes from the U.S. Health and Retirement Study participants racialized as Black. A purposive sample of participants born after the Brown v. Board ruling (born 1954-59) were selected who completed the modified Telephone Interview for Cognitive Status between 2010 and 2020 (N=1381). We tested associations of exposure to structural racism and resilience before birth, and during childhood, young-adulthood, and midlife with cognitive trajectories in mid-late life using mixed-effects regression models.

Results

Older adults born in places with higher state-level structural socioeconomic racism experienced a more rapid cognitive decline in later life compared to those with lower levels of exposure. In addition, participants born in places with higher levels of state-level structural socioeconomic resilience experienced slower cognitive change over time than their counterparts.

Discussion

These findings reveal the impact of racist U.S. policies enacted in the past that influence cognitive health over time and dementia risk later in life.

A Scoping Review of Neighborhoods and Cognitive Health Disparities Among US Midlife and Older Adults

Objectives: The neighborhood environment may be an important determinant of racial/ethnic disparities in cognitive function. To understand how neighborhoods are linked to cognition across racial/ethnic groups, this scoping review organizes research investigating relationships between multiple neighborhood domains and cognitive function in diverse samples of US midlife and older adults. Methods: PubMed/MEDLINE, Web of Science, and CAHL were used to extract quantitative disparities-focused studies (n = 17) that included US adults ages 50+, racial/ethnic minoritized populations, cognitive dependent variable(s), and neighborhood-level independent variable(s) published from January 2010 to October 2021. Results: Studies demonstrate variation within and between racial/ethnic groups in how neighborhood factors are associated with cognition. Economically and socially advantaged neighborhoods were associated with better cognition. Findings were mixed for built and neighborhood composition measures. Discussion: More research with greater racial/ethnic representation is needed to disentangle which aspects of the neighborhood are most salient for specific cognitive function domains across diverse populations.

Disparities in Access to Spasticity Chemodenervation Specialists in the United States: A Retrospective Cross-Sectional Study

OBJECTIVE

The aim of the study is to explore variations in access to spasticity chemodenervation specialists across several geographical, ethnic, racial, and population density factors.

DESIGN

This is a retrospective cross-sectional study on Medicare Provider Utilization and Payment Data. Providers with substantial adult spasticity chemodenervation practices were included. Ratios were assessed across geographical regions as well as hospital referral regions. A multivariate linear regression model for the top 100 hospital referral regions by beneficiary population was created, using backward stepwise selection to eliminate variables with P values > 0.10 from final model.

RESULTS

A total of 566 providers with spasticity chemodenervation practices were included. Unadjusted results showed lower access in nonurban versus urban areas in the form of higher patient:provider ratios (83,106 vs. 51,897). Access was also lower in areas with ≥25% Hispanic populations (141,800 vs. 58,600). Multivariate linear regression results showed similar findings with urban hospital referral regions having significantly lower ratios (-45,764 [ P = 0.004] vs. nonurban) and areas with ≥25% Hispanic populations having significantly higher ratios (+96,249 [ P = 0.003] vs. <25% Hispanic areas).

CONCLUSIONS

Patients in nonurban and highly Hispanic communities face inequities in access to chemodenervation specialists. The Medicare data set analyzed only includes 12% of the US patient population; however, this elderly national cross-sectional cohort represents a saturated share of patients needing access to spasticity chemodenervation therapy. Future studies should venture to confirm whether findings are limited to this specialization, and strategies to improve access for these underserved communities should be explored.

Life Course Religious Attendance and Cognitive Health at Midlife: Exploring Gendered Contingencies

A growing body of literature suggests that religious attendance might mitigate processes of cognitive decline associated with aging. However, few studies have made adequate linkages with the life course perspective. We draw from over 35 years of prospective panel data from the National Longitudinal Study of Youth (1979-2015) to assess the associations of cumulative exposures to religious attendance over the life course (childhood and midlife) for self-rated cognitive health and working memory (as assessed by the Serial 7s task). Our results suggest that midlife adults who attended religious services consistently between childhood and adulthood had higher self-rated cognitive health and better working memory. Women were also found to receive stronger benefits to self-rated cognitive health from consistent religious practice between childhood and adulthood. This pattern of findings allows for greater reflection into the neural enrichment and neural depletion arguments proposed to explain the religion/cognitive health link in previous research.

Race, community disadvantage, and cognitive decline: Findings from KHANDLE and STAR

INTRODUCTION

Community disadvantage is associated with late-life cognition. Few studies examine its contribution to racial disparities in cognition/cognitive change.

METHODS

Inverse probability weighted models estimated expected mean differences in cognition/cognitive change attributed to residing in less advantaged communities, defined as cohort top quintile of Area Deprivation Indices (ADI): childhood 66-100; adulthood ADI 5-99). Interactions by race tested.

RESULTS

More Black participants resided in less advantaged communities. Semantic memory would be lower if all participants had resided in less advantaged childhood (b = -0.16, 95% confidence interval [CI] = -0.30, -0.03) or adulthood (b = -0.14, 95% CI = -0.22, -0.04) communities. Race interactions indicated that, among Black participants, less advantaged childhood communities were associated with higher verbal episodic memory (interaction p-value = 0.007) and less advantaged adulthood communities were associated with lower semantic memory (interaction p-value = 0.002).

DISCUSSION

Examining racial differences in levels of community advantage and late-life cognitive decline is a critical step toward unpacking community effects on cognitive disparities.

Measurement and structural invariance of a neuropsychological battery among Middle Eastern/North African, Black, and White older adults

OBJECTIVE

There is a lack of guidance on common neuropsychological measures among Arabic speakers and individuals who identify as Middle Eastern/North African (MENA) in the United States. This study evaluated measurement and structural invariance of a neuropsychological battery across race/ethnicity (MENA, Black, White) and language (Arabic, English).

METHOD

Six hundred six older adults (128 MENA-English, 74 MENA-Arabic, 207 Black, 197 White) from the Detroit Area Wellness Network were assessed via telephone. Multiple-group confirmatory factor analyses examined four indicators corresponding to distinct cognitive domains: episodic memory (Consortium to Establish a Registry for Alzheimer's Disease [CERAD] Word List), language (Animal Fluency), attention (Montreal Cognitive Assessment [MoCA] forward digit span), and working memory (MoCA backward digit span).

RESULTS

Measurement invariance analyses revealed full scalar invariance across language groups and partial scalar invariance across racial/ethnic groups suggesting a White testing advantage on Animal Fluency; yet this noninvariance did not meet a priori criteria for salient impact. Accounting for measurement noninvariance, structural invariance analyses revealed that MENA participants tested in English demonstrated lower cognitive health than Whites and Blacks, and MENA participants tested in Arabic demonstrated lower cognitive health than all other groups.

CONCLUSIONS

Measurement invariance results support the use of a rigorously translated neuropsychological battery to assess global cognitive health across MENA/Black/White and Arabic/English groups. Structural invariance results reveal underrecognized cognitive disparities. Disaggregating MENA older adults from other non-Latinx Whites will advance research on cognitive health equity. Future research should attend to heterogeneity within the MENA population, as the choice to be tested in Arabic versus English may reflect immigrant, educational, and socioeconomic experiences relevant to cognitive aging. (PsycInfo Database Record (c) 2023 APA, all rights reserved).