Impact of socioeconomic conditions across the life course on epigenetic age acceleration: evidence from a longitudinal cohort

BACKGROUND: We investigated whether adulthood socioeconomic status (SES) mediates the association between childhood SES and biological aging in a longitudinal cohort (N = 359). METHODS: SES was measured using composite scores from prospective measures in childhood and at age 50. Peripheral blood DNA methylation (DNAm) was measured at approximately 50 years of age. DNAm age acceleration (AA) was quantified for DNAm "clocks" (Horvath, Hannum, PhenoAge, GrimAge) and a DNAm pace-of-aging measure (DunedinPACE). Linear regression was used to evaluate the associations between SES at each life stage and DNAm AA. Adulthood SES was evaluated as a mediator between childhood SES and DNAm AA using marginal structural models. RESULTS: Compared to high childhood SES, low childhood SES was associated with AA for GrimAge (β = 0.99, 95% confidence interval [CI]: 0.08, 1.91) and DunedinPACE (β = 0.05, 95% CI: 0.02, 0.08). Low adulthood SES, compared to high adulthood SES, was also associated with AA for GrimAge (β = 2.31, 95% CI: 1.35, 3.28) and DunedinPACE (β = 0.05, 95% CI: 0.02, 0.08). The association between childhood SES and both clocks were partially mediated by adulthood SES. No other clocks were associated with SES. CONCLUSION: Early and late-life socioeconomic conditions accelerate biological aging. Larger studies exploring mediators and interventions are needed for equitable aging mitigation.