Socioeconomic Status, Biological Aging, and Memory in a Diverse National Sample of Older US Men and Women

Importance Exposure to socioeconomic disadvantage is associated with rapid cognitive aging. Biological aging, the progressive loss of system integrity that occurs as we age is proposed as a modifiable process mediating this health inequality. Objective To test the hypothesis that socioeconomic disparities in cognitive aging in older adults is explained by accelerated biological aging. Design Observational cohort study. Setting U.S. Health and Retirement Study DNA-methylation sub-study. Participants N=3,648 (49% male) adults aged 50-100 (M=70, SD=10) with DNA methylation data. Exposures Socioeconomic status (SES) was measured from years of education and household wealth. The extent and pace of biological aging were quantified using three DNA-methylation measures: PhenoAge, GrimAge, and DunedinPoAm. Main Outcomes and Measures Cognitive aging was measured from repeated longitudinal assessments of immediate and delayed word recall. Latent growth curve modeling estimated participants’ level of memory performance and rate of decline over 2-11 follow-up assessments spanning 2-20 years. Models were estimated to assess whether the relationship between SES and memory trajectories was mediated by biological aging. Results Older adults with lower SES had lower memory performance, faster decline and exhibited accelerated biological aging (SES β=.33, 99% CI[.30-.36], biological-aging measure effect size associations ranged from .08 to .20). Accelerated biological aging was associated with decreased memory performance and faster memory decline (effect-size range .03 to .18). Higher SES was associated with slower biological aging for White and Black men and women, but not Latinx participants. The relationship between biological aging measures and memory was weaker for Black and Latinx participants compared with White people. In mediation analysis, biological aging accounted for 3-9% of the SES-memory gradient in White participants. There was no evidence of mediation in Black or Latinx participants. Conclusions and Relevance Among a national sample of older adults, DNA-methylation measures of biological aging were associated with memory trajectories in White, but not Black or Latinx older adults. These results challenge the assumption that DNA-methylation biomarkers of aging that were developed in primarily White people can quantify aging processes affecting cognition in Black and Latinx older adults.