Dementia is a common and disabling brain disorder among older adults that has consequences for independence, functional decline, institutionalization, and mortality. Previous research has identified multiple biological, genetic, and behavioral factors that are associated with cognitive impairment and decline. Recently, a parallel literature has looked beyond individual-level factors to consider the role of the social and built environment. Findings suggest that residence in socioeconomically advantaged neighborhoods may promote cognitive function and/or buffer cognitive decline in part through their greater density of physical resources (recreational centers, gyms, parks, walking paths, healthy food stores) as well as social and institutional resources (libraries, bookstores, community centers, social clubs) that promote physical activity and facilitate mental stimulation (e.g. social interaction) that may buffer cognitive decline with age. However, these relationships have not been empirically tested with national population-based data.
This study will examine the moderating role of neighborhood built and social environments on trajectories of cognitive function in a national sample of Americans followed since 2003. We will identify how features of the social and built environment are related to rates of decline in cognitive function among participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study. REGARDS is a national longitudinal cohort study of over 30,0000 black and white individuals age 45+ ongoing since 2003. In addition to being a longitudinal study collecting data on stroke and cognitive function at 6 month intervals, the study also tracks residential locations through geographic coordinates that will be linked to secondary sources to characterize the social and built environment. By augmenting this existing NIH-funded longitudinal cohort study with neighborhood characteristics, this study will provide a critical opportunity to examine the role of neighborhood built and social environments for preventing cognitive decline in Americans as they age.
Aim 1: To characterize the built and social environment for a sub-sample of older adults in the REGARDS study with respect to the physical and social resources that could mitigate cognitive decline. We will make use of publicly available sources of socioenvironmental context (e.g. land use, walkability, crime, community centers, recreational centers) that will be linked to REGARDS respondents using geographic identifiers over time.
Aim 2: To examine cross-sectional variation in older adult cognitive function according to the density of social and physical resources within residential neighborhoods.
Hypothesis 1: Cognitive function will vary significantly across residential neighborhoods, and will be higher for individuals living in neighborhoods with a greater density of social and physical resources.
Aim 3: To use longitudinal data to examine changes in cognitive function over time, and to link neighborhood resources to rates of cognitive decline over time.
Hypothesis 2: All other factors being equal, older adults living in more resource-intensive neighborhoods will exhibit slower rates of cognitive decline over time than similar adults living in neighborhoods with fewer resources.
Aim 4: To determine the extent to which built and social environments explain racial disparities in cognitive function.
Hypothesis 3: Disparities in access to resource-intensive neighborhoods will account for part of the observed racial difference in cognitive function.