Social Inequalities Linked to Accelerated Biological Aging
Studies have reported mixed results for epigenetic clocks, raising questions about their validity. However, more robust clocks have provided a clearer evidence base.
Many studies have reported null results for the first generation of epigenetic clocks, raising questions about the underlying hypothesis as well as the validity of the clocks themselves. Only as more robust and reliable second- and third-generation clocks entered the literature did the evidence base begin to crystalize. The authors identified 140 eligible studies from a pool of 858 articles, comprising a total of 1,065 effect sizes derived from 79 unique cohorts drawn from 23 different countries. Individuals of lower socioeconomic status tended to exhibit accelerated epigenetic-clock-measured biological aging, as compared with individuals of higher socioeconomic status. The magnitude of this association was moderated by clock generation, with stronger associations found for second- and third-generation measures. These findings also extended to younger populations, with children from lower-socioeconomic-status families exhibiting a faster pace of aging. The results were consistent across different race and ethnic groups within the USA, with Black and Latinx individuals showing accelerated biological aging compared to white individuals.