Social adversity and epigenetic aging: a multi-cohort study on socioeconomic differences in peripheral blood DNA methylation

Abstract

Low socioeconomic status (SES) is associated with earlier onset of age-related chronic conditions and reduced life-expectancy, but the underlying biomolecular mechanisms remain unclear. Evidence of DNA-methylation differences by SES suggests a possible association of SES with epigenetic age acceleration (AA). We investigated the association of SES with AA in more than 5,000 individuals belonging to three independent prospective cohorts from Italy, Australia, and Ireland. Low SES was associated with greater AA (β = 0.99 years; 95% CI 0.39,1.59; p = 0.002; comparing extreme categories). The results were consistent across different SES indicators. The associations were only partially modulated by the unhealthy lifestyle habits of individuals with lower SES. Individuals who experienced life-course SES improvement had intermediate AA compared to extreme SES categories, suggesting reversibility of the effect and supporting the relative importance of the early childhood social environment. Socioeconomic adversity is associated with accelerated epigenetic aging, implicating biomolecular mechanisms that may link SES to age-related diseases and longevity.

Figure 1

SES–AA association: Bar-plots indicating the estimated effect sizes (in years) and standard errors of the association of SES with Hannum AA (a: model 1 with basic adjustments, b: model 2 adjusted for NCD risk factors), and life-course SES trajectory with Hannum AA (c: model 1 with basic adjustments, d: model 2 adjusted for NCD risk factors).

Figure 2

Sensitivity analysis: Forest-plots indicating the estimated effect sizes (in years; black dots) and 95% confidence intervals (horizontal lines) for the association of SES (a: three studies meta-analysis) and life-course SES trajectory (b: EPIC Italy and TILDA meta-analysis) with Hannum AA, estimated each time in different subsets of the overall sample.