Social inequalities linked to accelerated biological aging

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“Many studies 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,” explains co-author Daniel Belsky. “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. Across studies, individuals of lower socioeconomic status tended to exhibit accelerated epigenetic-clock-measured biological aging, as compared with individuals of higher socioeconomic status. Importantly, the magnitude of this association between socioeconomic status and biological aging was moderated by clock generation. Associations were stronger for the second- and third-generation measures (including GrimAge acceleration, DunedinPoAm and DunedinPACE) than for first-generation DNA methylation clocks. The findings also extended to younger populations. In an analysis restricted to DNA methylation in children, authors found that children living in lower-socioeconomic-status families exhibited a faster pace of aging than their more affluent peers, which suggests that social inequalities may become biologically embedded early in life. These findings were consistent in different race and ethnic groups within the USA, where Black and Latinx individuals showed accelerated biological aging as compared with white individuals.