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

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.

Social infrastructure and the prevalence of deaths of despair: The role of concentrated disadvantage

This study aims to understand the associations between social infrastructure and deaths of despair (DoD), with special attention to the role of concentrated disadvantage. I assembled a county-level dataset in the United States from various sources. A series of multilevel regression results indicate that (1) social infrastructure is associated with DoD; a higher density of public institutions (e.g., libraries) and religious organizations are associated with a lower prevalence of DoD; and (3) the associations between social infrastructure and DoD vary by concentrated disadvantage in that the protective effects of social infrastructure are observed only in less disadvantaged countries.

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.

Neighborhood Built Environments and Health in Later Life: A Literature Review

Objectives: This literature review aims to assess the current state of the field linking neighborhood environments to later-life health and wellbeing. Methods: We used electronic databases (e.g., PubMed, Google Scholar, and ProQuest) to search for studies published between 2010 and 2022 examining associations between neighborhood built environmental variables and later-life physical, cognitive, mental, and social health outcomes. Results: Among 168 studies reviewed, the majority were quantitative (n = 144) and cross-sectional (n = 122). Neighborhood environmental variables significantly associated with later-life health outcomes included population density/rurality, walkability/street connectivity, access to services and amenities, neighborhood quality and disorder, and parks/green/blue/open space. Neighborhoods operated through behavioral and biological pathways including hazardous exposures, affective states (e.g., stress and restoration), and lifestyle (e.g., exercise, socialization, and diet). Discussion: Neighborhoods and healthy aging research is a burgeoning interdisciplinary and international area of scholarship. Findings can inform upstream community interventions and strengthen clinical care.

Effects of neighborhood built environment on cognitive function in older adults: a systematic review

BACKGROUND

In the background of an aging population, the risk of cognitive impairment in the older population is prominent. Exposure to complex neighborhood built environments may be beneficial to the cognitive health of older adults, and the purpose of this study was to systematically review the scientific evidence on the effects of neighborhood built environments on cognitive function in older adults.

METHODS

Keywords and references were searched in Web of Science, Pubmed, PsycINFO, and MEDLINE. Studies examining the relationship between the built environment and cognitive function in older adults were included. The neighborhood built environment as an independent variable was classified according to seven aspects: density, design, diversity, destination accessibility, public transportation distance, blue/green space, and built environment quality. The cognitive function as the dependent variable was classified according to overall cognitive function, domain-specific cognitive function, and incidence of dementia. The quality of the included literature was assessed using the National Institutes of Health's Observational Cohort and Cross-Sectional Study Quality Assessment Tool.

RESULTS

A total of 56 studies were included that met the inclusion criteria, including 31 cross-sectional studies, 23 longitudinal studies, 1 cross-sectional study design combined with a case-control design, and 1 longitudinal study design combined with a case-control design. Most of the studies reviewed indicate that the built environment factors that were positively associated with cognitive function in older adults were population density, street connectivity, walkability, number of public transportation stops around the residence, land use mix, neighborhood resources, green space, and quality of the neighborhood built environment. Built environment factors that were negatively associated with cognitive function in older adults were street integration, distance from residence to main road. The relationship between residential density, destination accessibility, and blue space with cognitive function in older adults needs to be further explored.

CONCLUSION

Preliminary evidence suggests an association between the neighborhood built environment and cognitive function in older adults. The causal relationship between the built environment and cognitive function can be further explored in the future using standardized and combined subjective and objective assessment methods, and longitudinal or quasi-experimental study designs. For public health interventions on the cognitive health of older adults, it is recommended that relevant authorities include the neighborhood built environment in their intervention programs.

Altered place engagement since COVID-19: A multi-method study of community participation and health among older americans

Little is known about longer-term changes to community participation since the COVID-19 pandemic onset and potential implications for health and wellbeing in later life. This multi-method investigation analyzes national data from the COVID-19 Coping Study. Statistical analyses of survey data (n = 1,630; mean age 67.9 years; data collected April/May 2022) identified that adults residing in the US still tended to stay inside their homes more often since the pandemic onset. Overall, participants decreased their engagement with amenities such as eateries, gyms, and arts and cultural sites. Reflexive thematic analysis of semi-structured in-depth interviews (n = 57; mean age 70.7 years; data collected May-July 2021) identified altered community participation with perceived long-term impacts on physical, mental, and social health and wellbeing. The results provide novel insights about the critical nature of 'third places' to support later life, and policy implications to strengthen community environments. Investment in outdoor, well-ventilated, and distanced third places may support wellbeing.

Neighborhood 'Disamenities': local barriers and cognitive function among Black and white aging adults

BACKGROUND

This study examined the association between cognitive function and three neighborhood 'disamenities' that may pose local barriers to utilizing community resources and increase risk for cognitive decline.

METHOD

Using national data from 21,165 urban- and suburban-dwelling Black and white adults (mean age: 67 years) in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study, we assessed global cognitive function through a factor score of five cognitive screening tests. General Additive Mixed Models (GAMM) tested whether residing in areas with more polluting sites, highways, and limited walkability was associated with worse cognitive function.

RESULTS

Limited walkability and the presence of polluting sites had a significant negative association with cognitive function after controlling for individual and neighborhood factors.

CONCLUSION

Neighborhood disamenities may be linked to cognitive function among aging residents. Identifying neighborhood factors that pose barriers to accessing community resources may inform upstream policy applications to reduce risk for cognitive decline.

Olfaction in (Social) Context: The Role of Social Complexity in Trajectories of Older Adults' Olfactory Abilities

Objectives: Olfaction is an important correlate of later-life health, including cognition and mortality risk. Environmental enrichment protects against olfactory decline, yet little research considers the social context as a source of sensory enrichment or stimulation. This study examines how exposure to social complexity (i.e., diversity or novelty in social networks and activities) shapes later-life olfaction. Methods: Cross-sectional and longitudinal ordered logit models analyze data from 1,447 older adults interviewed at Rounds 1 and 2 of the National Social Life, Health, and Aging Project. Results: Exposure to greater social complexity (larger social networks, greater network diversity) is associated with significantly better olfaction at baseline. Increases in network diversity and fewer network losses significantly protect against olfactory decline over time. Discussion: Findings highlight the social context as an important, yet relatively overlooked source of sensory enrichment, and underscore the need for biological applications to integrate social life dynamics into studies of health trajectories.

Cognability: An Ecological Theory of neighborhoods and cognitive aging

While a growing body of evidence points to potentially modifiable individual risk factors for dementia, the built and social environments in which people develop and navigate cognitive decline are largely overlooked. This paper proposes a new theoretical concept, Cognability, to conceptualize how supportive an area is to cognitive health among aging residents. Cognability incorporates a constellation of both positive and negative neighborhood features related to physical activity, social interaction and cognitive stimulation in later life. We analyzed data from the REasons for Geographic And Racial Differences in Stroke Study, a national sample of older Black and white adults in the United States (n = 21,151; mean age at assessment = 67; data collected 2006-2017). Generalized additive multilevel models examined how cognitive function varied by neighborhood features. Access to civic and social organizations, recreation centers, fast-food and coffee establishments, arts centers, museums, and highways were significantly associated with cognitive function. Race-, gender-, and education-specific models did not yield substantial improvements to the full-model. Our results suggest that the unequal distribution of amenities and hazards across neighborhoods may help account for considerable inequities observed in cognitive health among older adults. Cognability advances ecological theories of aging through an innovative "whole neighborhood" approach. It aims to identify which specific neighborhood features are most protective of cognitive health among aging adults to inform upstream public health initiatives, community interventions, and policy.

Role of Neighborhood Physical Disorder and Social Cohesion on Racial and Ethnic Disparities in Dementia Risk

Objectives: To analyze how neighborhood physical disorder and social cohesion are associated with racial and ethnic disparities in dementia risk. Methods: Nine years of data (2011-2019) were retrieved from the National Health and Aging Trends Study, a nationally representative U.S. older adult (age 65+) sample. Cox regression analyzed time to dementia diagnosis using composite scores for neighborhood physical disorder and social cohesion. Results: Higher baseline neighborhood physical disorder (Adjusted Hazard Ratio [aHR]=1.11, 95% Confidence Interval [CI]=1.01-1.23) and increased disorder at follow-up (aHR=1.10, 95% CI=1.01-1.19) significantly increased dementia risk. Hispanic older adults with higher physical disorder at baseline (aHR=0.62, 95% CI=0.49-0.79) and follow-up (aHR=0.81, 95% CI=0.67-0.98) had a significantly decreased dementia risk. There were no significant associations for social cohesion. Discussion: Physical but not social neighborhood characteristics are associated with dementia risk. Future research is needed to understand protective mechanisms for dementia among Hispanic older adults in neighborhoods with high physical disorder.