Environmental Resources for Individual Cognitive Health/Resilience (EnRICH) - Excess risk for Alzheimer’s Disease and related dementias (ADRD) persists among sub-groups of older adults, a population projected to more than double by 2060. ADRD prevention research has focused on individual factors such as hypertension, with less attention to environmental determinants. Yet both the distribution of individual factors and the effects of individual factors are potentially shaped by features of the residential environment—such as green space, air pollution, ambient temperature, noise, walkability, neighborhood amenities, access to transit, and neighborhood socio-economic status. Environmental factors may acutely shape ADRD risk. Further, combinations of environmental- and individual-level factors may exacerbate vulnerability with age to cognitive decline and loss of instrumental and basic activities of daily living (ADLs) which are dependent on cognition. Prior evidence on environmental factors and ADRD risk evaluates one factor at a time, even though environmental factors are experienced in combination. These exposure combinations are part of the exposome—the totality of environmental exposures that are experienced across the life-course. Studies on how the exposome shapes individual-level risk factors for ADRD risk are unusual, and studies that compare across sub-groups of the population are scarce. To address this significant gap, we propose to link time-varying high-resolution environmental metrics to five NIH-funded cohorts in the US: Health and Retirement Study (HRS), the REasons for Geographic and Racial Differences in Stroke (REGARDS), the Kaiser Healthy Aging and Diverse Life Experiences (KHANDLE) cohort, the Study of Healthy Aging in African Americans (STAR), and the Multi-Ethnic Study of Atherosclerosis (MESA; combined N=82,500). This study will evaluate how the exposome shapes the risk of cognitive decline (Aim 1), independence loss in ADLs (Aim 2) and MRI biomarkers of brain atrophy (Aim 3).6 Our central hypothesis is that protective environmental conditions (high levels of green space, walkability, neighborhood amenities, and access to transit, and low levels of air pollution, ambient temperature, noise, and neighborhood socio-economic status) will be associated with better cognitive outcomes, better individual risk factors, and attenuated effects of individual risk factors on cognitive outcomes decades later. We anticipate the benefits of environmental resources for reducing ADRD will differ among sub-groups of the population. The proposed study will identify modifiable environmental factors that may reduce sub-population differences in ADRD. The comprehensive multi-dimensional spatial datasets developed in this project will be applicable to other epidemiological studies that consider biological and behavioral pathways through which the environment affects ADRD risk.
