Abstract

Background: Older individuals spend substantial periods in their local surroundings, making environmental aspects such as socioeconomic challenges, racial isolation, limited access to nutritious foods, restricted recreational spaces, and lower social connections critical to cognitive well-being. DNA methylation, a key epigenetic modification, has been linked to community attributes and neurocognitive functions, potentially acting as an intermediary in these relationships.

Methods: This study assessed whether DNA methylation levels in white blood cells mediate the link between neighborhood attributes and cognitive functions (N = 542) or white matter hyperintensities (WMH) (N = 466) among elderly African Americans who were free from dementia at baseline, drawn from the Genetic Epidemiology Network of Arteriopathy (GENOA).

Findings: Within a one-mile radius of a participant’s residence, the presence of an additional fast food outlet or liquor-selling convenience store per square mile showed a minor association with improved visual tracking time. Moreover, each added alcohol-serving venue per square mile correlated with an increased delayed recall score, suggesting enhanced memory performance (all p < 0.05). No significant associations were identified between neighborhood features and WMH, and DNA methylation did not mediate these relationships.

Conclusions: Social interaction within food venues may partially explain the observed cognitive benefits. Further studies are required to confirm these findings and explore potential intervention strategies aimed at fostering cognitive resilience among aging adults, particularly within at-risk populations.

Introduction

Dementia manifests through progressive cognitive decline, ultimately impairing daily functions. Among older U.S. adults, nearly 10% are diagnosed with dementia, while 22% exhibit mild cognitive impairment (MCI). Conditions such as Alzheimer’s disease (AD) and vascular dementia (VaD) impose significant burdens on families and healthcare infrastructure. Small vessel disease (SVD), identified via MRI as WMH, contributes to a considerable portion of ischemic strokes and is linked to cognitive deterioration.

While no definitive cure exists, research suggests cognitive exercises and cardiovascular risk management may delay dementia onset. While individual risk factors such as education, smoking, and physical activity are well-documented, growing attention is being directed toward the role of neighborhood environments in shaping health outcomes.

Methods

The study utilized data from the GENOA project, which tracks genetic influences on hypertension-related damage. African American participants were selected from Jackson, MS. Cognitive assessments included tests measuring memory, processing speed, language fluency, and attention tracking. Brain scans determined WMH volume, while DNA methylation levels were analyzed from blood samples.

Neighborhood characteristics were evaluated using GIS mapping to estimate the density of food outlets, social venues, and socioeconomic disadvantage indicators. Statistical models assessed relationships between these environmental factors, cognitive performance, and WMH.

Results

Higher densities of fast food establishments and liquor-selling stores correlated with improved visual tracking time. Additionally, a greater number of alcohol-serving locations was linked to better memory retention. However, no significant associations were found with WMH volume. DNA methylation was not observed as a mediating factor in these relationships.

Discussion

Contrary to initial expectations, neighborhood features traditionally deemed unhealthy appeared to offer cognitive benefits, possibly due to increased opportunities for social interaction. Prior studies have presented conflicting findings on the relationship between neighborhood environments and cognition. Some research suggests that proximity to community hubs enhances mental stimulation, while others highlight potential negative influences such as stress and environmental toxins.

Further investigations should explore potential interventions that optimize neighborhood resources to support cognitive health. Longitudinal studies may provide deeper insights into how neighborhood changes over time impact cognitive aging.

Conclusion

Neighborhood environments, including food and social venues, may play a role in cognitive function among older African Americans. Future research should examine mechanisms driving these associations and develop strategies to enhance neighborhood infrastructure for improved aging outcomes.