Project Summary
Excess risk for Alzheimer’s Disease and related dementias (ADRD) persists among Black and Latino 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 deprivation. Environmental factors may acutely shape ADRD risk
in Black and Latino communities affected by unequal opportunities due to systemic racism. 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 comes from predominantly White samples, and
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 racial/ethnic groups are scarce.
To address this significant gap, we propose to link time-varying high-resolution environmental metrics to five
NIH-funded racially and ethnically diverse 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) in racially/ethnically diverse groups.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 deprivation) 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 be stronger among Black and Latino adults than White participants. The proposed study will identify
modifiable environmental factors that may reduce racial and ethnic disparities 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.