Socioeconomic Status, Lifestyle, and DNA Methylation Age Among Racially and Ethnically Diverse Adults: NIMHD Social Epigenomics Program

Relationship between physical activity and DNA methylation-predicted epigenetic clocks

This study investigates the relationship between physical activity (PA) levels and DNA methylation (DNAm)-predicted epigenetic clocks in a U.S. population sample (n = 948, mean age 62, 49% female). Eight epigenetic clocks were analyzed, revealing that higher PA levels were significantly associated with younger biological ages across all indicators, with the strongest effects observed for SkinBloodAge and LinAge. Multivariable linear regression models, adjusted for sociodemographic and lifestyle factors, highlighted the potential of PA to reduce biological ageing. Subgroup analyses indicated that these associations were more pronounced among non-Hispanic whites, individuals with a BMI of 25-30, and former smokers, suggesting that the impact of PA varies across different groups. These findings emphasize the role of PA in slowing biological ageing and reducing age-related health risks. Promoting regular PA, especially among older adults and those with higher BMI, could improve well-being and lifespan, highlighting PA as a modifiable factor in healthy ageing and age-related disease prevention.

Quantification of Epigenetic Aging in Public Health

Estimators of biological age hold promise for use in preventive medicine, for early detection of chronic conditions, and for monitoring the effectiveness of interventions aimed at improving population health. Among the promising biomarkers in this field are DNA methylation-based biomarkers, commonly referred to as epigenetic clocks. This review provides a survey of these clocks, with an emphasis on second-generation clocks that predict human morbidity and mortality. It explores the validity of epigenetic clocks when considering factors such as race, sex differences, lifestyle, and environmental influences. Furthermore, the review addresses the current challenges and limitations in this research area.

Common DNA sequence variation influences epigenetic aging in African populations

Aging is associated with genome-wide changes in DNA methylation in humans, facilitating the development of epigenetic age prediction models. However, most of these models have been trained primarily on European-ancestry individuals, and none account for the impact of methylation quantitative trait loci (meQTL). To address these gaps, we analyzed the relationships between age, genotype, and CpG methylation in 3 understudied populations: central African Baka (n = 35), southern African ‡Khomani San (n = 52), and southern African Himba (n = 51). We find that published prediction methods yield higher mean errors in these cohorts compared to European-ancestry individuals, and find that unaccounted-for DNA sequence variation may be a significant factor underlying this loss of accuracy. We leverage information about the associations between DNA genotype and CpG methylation to develop an age predictor that is minimally influenced by meQTL, and show that this model remains accurate across a broad range of genetic backgrounds. Intriguingly, we also find that the older individuals and those exhibiting relatively lower epigenetic age acceleration in our cohorts tend to carry more epigenetic age-reducing genetic variants, suggesting a novel mechanism by which heritable factors can influence longevity.

Advancing Health Disparities Science Through Social Epigenomics Research

Importance

Although scientific and technological discoveries have improved the health of the US population overall, racial and ethnic minority (American Indian and Alaska Native, Asian, Black or African American, Hispanic or Latino, or Native Hawaiian and Pacific Islander persons) and socioeconomically disadvantaged populations continue to experience a disproportionate burden of disease and other adverse health conditions. To better understand and address the drivers of health disparities and inform the development of effective interventions, integrative mechanistic studies examining the dynamic interplay of multiple factors across the life course and even between generations are needed. The emerging field of social epigenomics, which seeks to link social stressors and protective factors to health status through the examination of epigenomic modifications of various biological pathways, is one promising area of research contributing to this need.

Observations

This thematic issue of JAMA Network Open highlights new findings from the grantees of the National Institutes of Health (NIH) Social Epigenomics Program. These findings, taken together, examine the associations of a variety of social, behavioral, and structural factors throughout the life course with epigenomic and other biological changes among populations experiencing health disparities. The studies link early-life exposures, structural inequities, and behavioral factors and interventions to epigenetic changes, and in some studies, later health outcomes. While there is still more work to be done to fully characterize the mechanistic pathways linking social exposures to epigenetic changes and health outcomes, the body of work presented in this special issue represents solid progress toward this goal.

Conclusions and Relevance

The studies highlighted in this special issue demonstrate important scientific progress in the complex integration of social determinants of health and health disparities with biological pathways and health outcomes to improve understanding of the mechanisms underlying health disparities among various underserved populations. Continued progress remains important in integrating different disciplines to transform the field of health disparities research.