Background and Objectives:Exposure to socioeconomic disadvantage is associated with early-onset 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. We examined whether socioeconomic disparities in cognitive aging in mid-to late-life adults is explained by accelerated biological aging similarly across race, ethnicity and sex/gender.Methods:Data was from a prospective cohort study of the U.S. Health and Retirement Study DNA-methylation sub-study. Socioeconomic status (SES) was measured from years of education and household wealth at baseline. The extent and pace of biological aging were quantified using three DNA-methylation measures: PhenoAge, GrimAge, and DunedinPoAm. 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. Multiple-group models were estimated to assess whether the relationship between SES and memory trajectories was mediated by biological aging across racial-ethnic by sex/gender subgroups.Results:Data from a total of 3,997 adults aged 50-100 were analyzed. Participants with lower SES had lower memory performance, faster decline and exhibited accelerated biological aging (SES effect size associations (β) ranged from .08 to .41). Accelerated biological aging was associated with decreased memory performance and faster memory decline (effect-size range .03 to .23). SES-biological aging associations were strongest for White men and women and weakest for Latinx women. The relationship between biological aging measures and memory was weaker for Black participants compared with White and Latinx people. In mediation analysis, biological aging accounted for 4-27% of the SES-memory gradient in White participants. There was little evidence of mediation in Black or Latinx participants.Discussion:Among a national sample of mid-to late-life adults, DNA-methylation measures of biological aging were variably associated with memory trajectories and SES across White, Black, and Latinx mid-to late-life adults. These results challenge the assumption that DNA-methylation biomarkers of aging that were developed in primarily White people can equivalently quantify aging processes affecting cognition in Black and Latinx mid-to late-life adults.
Background and Objectives:Lifestyle activities, such as physical activity and cognitive stimulation, may mitigate age-associated cognitive decline, delay dementia onset, and increase cognitive reserve. Whether the association between lifestyle activities and cognitive reserve differs by sex and APOE4 status is an understudied yet critical component for informing targeted prevention strategies. The current study examined interactions between sex and physical or cognitive activities on cognitive reserve for speed and memory in older adults.Methods:Research participants with unimpaired cognition, mild cognitive impairment, or dementia from the Washington Heights-Inwood Columbia Aging Cohort were included in this study. Cognitive reserve scores for speed and memory were calculated by regressing out hippocampal volume, total gray matter volume, and white matter hyperintensity volume from composite cognitive scores for speed and memory, respectively. Self-reported physical activity was assessed using the Godin Leisure Time Exercise Questionnaire, converted to metabolic equivalents (METS). Self-reported cognitive activity (COGACT) was calculated as the sum of three yes/no questions. Sex by activity interactions and sex-stratified analyses were conducted using multivariable linear regression models, including a secondary analysis with APOE4 as a moderating factor.Results: 758 participants (mean age=76.11+6.31 years, 62% women) were included in this study. Higher METS was associated with greater speed reserve in women (β=0.04, CI: (0,0.08)), but not in men (β=0.004, CI: (-0.04,0.05)). METS was not associated with memory reserve in women or men. More COGACT was associated with greater speed reserve in the cohort (β=0.13, CI: (0.05,0.21)). More COGACT had a trend for greater memory reserve in women (β=0.06, CI: (-0.02,0.14)), but not in men (β=-0.04, CI: (-0.16,0.08)). Among women only, APOE4 carrier status attenuated relationships between METS and speed reserve (β=-0.09, CI: (-0.22,0.04)), and between COGACT and both speed (β=-0.26, CI: (-0.63,0.11)) and memory reserves (β=-0.20, CI: (-0.50,0.093)).Discussion:The associations of self-reported physical and cognitive activities with cognitive reserve are more pronounced in women, although APOE4 attenuates these associations. Future studies are needed to understand the causal relationship among sex, lifestyle activities, and genetic factors on cognitive reserve in older adults to best understand which lifestyle activities may be most beneficial and for whom.
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