DNA methylation clocks may help explain how social inequality influences mortality

“Race, ethnicity, education, income, and occupation are important social factors affecting health and longevity.”

BUFFALO, NY — May 27, 2026 — A new research paper was published in Volume 18 of Aging-US on May 8, 2026, titled “The mediating role of DNA methylation clocks in associations of race, ethnicity, education, income, and occupation with mortality: findings from NHANES 1999-2002.”

The study was led by first and corresponding author Hanyang Shen from the Department of Epidemiology and Population Health at Stanford University. In this study, the authors investigated whether DNA methylation aging biomarkers—often called epigenetic aging clocks—may help explain how social inequalities become biologically embedded and contribute to differences in mortality risk. Social factors such as race, ethnicity, educational attainment, household income, and occupation have long been associated with disparities in health outcomes and life expectancy. However, the biological mechanisms linking these social exposures to long-term disease risk and mortality remain incompletely understood.

Using nationally representative data from 2,402 adults in the U.S. National Health and Nutrition Examination Survey (NHANES) 1999–2002 linked to mortality follow-up data through 2019, the researchers examined thirteen different DNA methylation biomarkers alongside traditional clinical and behavioral risk factors. The study evaluated whether these epigenetic aging measures mediated associations between social stratification factors and all-cause mortality.

The findings showed that several DNA methylation clocks significantly mediated the relationship between social disadvantage and mortality risk. Among all biomarkers examined, GrimAge2 consistently demonstrated the strongest mediation effects, accounting for up to 52% of mortality disparities in some occupational comparisons. DunedinPoAm, a pace-of-aging biomarker, also demonstrated substantial mediation effects across multiple socioeconomic categories.

Importantly, the mediation effects observed for several DNA methylation biomarkers frequently exceeded those of traditional clinical risk factors measured in the study, including C-reactive protein and cholesterol-related markers. The results suggest that epigenetic aging measures may capture the cumulative biological effects of multiple social, environmental, behavioral, and physiological stressors simultaneously.

“Among all the 13 DNA methylation biomarkers available in NHANES, GrimAge2 consistently exhibited the strongest positive mediation capturing the social disparities on mortality up to 52% (95%CI: 26%-128%), followed by the DunedinPoAm.”

The researchers also identified notable differences across racial, educational, income, and occupational groups. Compared to White participants, Black and Hispanic participants showed significantly higher all-cause mortality risk after adjustment for demographic factors. Lower educational attainment, lower household income, and blue-collar occupational status were likewise associated with elevated mortality risk. The study further found that some epigenetic biomarkers mediated cardiovascular-specific and cancer-specific mortality disparities.

Interestingly, the authors observed that not all DNA methylation clocks behaved similarly. While physiologically trained clocks such as GrimAge2 and DunedinPoAm showed strong positive mediation effects, some biomarkers associated with telomere biology demonstrated inverse or negative mediation patterns in certain racial comparisons. The authors suggest these findings may reflect complex biological and social resilience mechanisms that require further investigation.

The paper also highlights the growing potential of DNA methylation biomarkers as integrative measures of biological aging. Unlike traditional biomarkers that typically reflect only a single physiological pathway, epigenetic clocks may capture the combined impact of inflammation, metabolic dysfunction, environmental exposures, psychosocial stress, and lifestyle-related factors over time.

Importantly, the authors emphasize that the study was observational and based on cross-sectional DNA methylation measurements, limiting causal interpretation. They note that additional longitudinal studies will be necessary to clarify how social exposures, biological aging processes, and mortality risk interact across the life course.

Overall, this study provides new evidence that DNA methylation aging biomarkers may help explain how social inequality becomes biologically embedded and contributes to disparities in mortality. By demonstrating that epigenetic aging measures can mediate a substantial proportion of social differences in health outcomes, the findings support the growing role of biological aging research in understanding population health disparities and long-term disease risk.

Paper DOI: https://doi.org/10.18632/aging.206377               

Corresponding author: Hanyang Shen – hyshen@stanford.edu

Abstract video: https://www.youtube.com/watch?v=XObIyirTJok

Keywords: race and ethnicity, social position, epigenetic aging, mediation analysis, mortality disparities

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