Social epigenetics of racial disparities in aging

Abstract

BackgroundRacial disparities in many aging‐related health outcomes are persistent and pervasive among older Americans. There are well‐documented inequities in the social determinants of health for older adults, including the social and physical environment, due to structural and environmental racism, but there is little understanding of the biological intermediates by which social determinants affect disparate health outcomes. Biological aging measured by DNA methylation (DNAm) is robustly associated with worse age‐related outcomes and higher social adversity. We hypothesize that individual social determinants, the social environment, and air pollution exposures interact to contribute to racial disparities in DNAm aging according to GrimAge and Dunedin Pace of Aging methylation (DPoAm).MethodWe performed retrospective cross‐sectional analyses among 3250 non‐Hispanic participants (80.3% white, 19.7% Black) in the Health and Retirement Study whose 2016 epigenetic age is linked to survey responses and geographic data. DNAm aging is defined as the residual after regressing epigenetic age on chronological age. Measures of the neighborhood social environment include the Social Deprivation Index and perceived social stress. Air pollution exposures include particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone. Individual‐level determinants include socioeconomic status, healthcare access, health status, and health behaviors. We implemented multivariable linear regression models to identify significant associations, interactions, and mediators in the relationship between each DNAm aging measure and the social and environmental determinants.ResultWe found on average Black individuals have significantly accelerated DNAm aging compared to white individuals (599% and 498%) according to GrimAge and DPoAm, respectively. Individual‐level factors evaluated account for approximately 43% of the disparity in GrimAge and 34% in DPoAm. Further results suggest that associations between neighborhood social environment and DNAm aging are significant and mediated by individual‐level factors. PM2.5 may be associated with DPoAm acceleration in certain sub‐populations. NO2 and ozone are not significantly associated with DNAm aging. We are investigating individual‐level factors that mediate social environmental exposures and increase vulnerability to PM2.5.ConclusionDNAm aging may play a role in social determinants “getting under the skin” and contributing to age‐related health disparities between Black and white Americans. Work is ongoing to determine the environmental and individual factors that contribute to these disparities.