Socioeconomic status across the life course and epigenetic age acceleration in adulthood: Evidence from two generations of a Filipino birth cohort study

PROJECT SUMMARY This study will examine the contributions of socioeconomic status (SES) over the lifecourse to epigenetic age acceleration across adulthood. Numerous studies have established that age-related degenerative disease and mortality follow SES gradients. Early life SES has been shown to be associated with many markers of health across the lifecourse independent of SES in adulthood. This suggests that age-related decline is not simply the result of individual lifestyle decisions in adulthood but that it is also influenced by the socioeconomic conditions that individuals grow and develop within across the lifecourse. “Epigenetic clocks,” which measure various dimensions of biological aging using DNA methylation, hold promise to help describe healthy versus pathological aging. Epigenetic age acceleration, defined as having advanced estimated epigenetic clock age relative to one’s chronological age, is highly predictive of future age-related degenerative disease and mortality. Adding to well-documented socioeconomic gradients in biomarkers of inflammation, immunological function, and cardiovascular disease risk, recent studies have found that lower SES is associated with increased epigenetic age acceleration, particularly when using epigenetic clocks trained on clinical or phenotypic markers of aging. However, much of this evidence comes from studies using retrospective data on SES, which may be affected by recall and other biases. This study is innovative because it uses rich longitudinal data on SES measured prospectively over two decades among the mother and offspring participants in the Cebu Longitudinal Health and Nutrition Survey (CLHNS). The CLHNS is an ongoing birth cohort study that has followed several thousand women and their children in Metropolitan Cebu, Philippines since 1983. Recent improvements in life expectancy in Cebu have corresponded to an increased public health burden of age-related disease and functional decline. DNA methylation data from blood samples collected in 2005 among both generations were used to measure epigenetic age acceleration from five epigenetic clocks shown to predict future health and aging in the CLHNS. This study addresses the following aims: 1) Estimate the total and direct associations between lifecourse SES measures and epigenetic age acceleration in young adulthood (for offspring) and middle adulthood (for mothers) and 2) In offspring, estimate associations between intergenerational educational attainment trajectories and epigenetic age acceleration. Training activities will focus on gaining skills in rigorous epidemiological methods for longitudinal exposures and mediation, including semiparametric methods that incorporate machine learning algorithms. Grounded in rigorous approaches from social epidemiology, this study will generate evidence to clarify the contributions of lifecourse SES to epigenetic aging across adulthood, while also identifying modifiable SES factors that may inform the design of interventions to reduce biological aging and age-related degenerative disease.