Longitudinal Changes in Epigenetic Age Acceleration Across Childhood and Adolescence

IMPORTANCE Individuals exposed to discrimination may exhibit greater epigenetic age acceleration (ie, cellular indicators of premature aging) over time, but few studies have examined longitudinal changes in epigenetic age acceleration, the heterogeneity in these changes for diverse groups of youths, and contextual explanations (ie, discrimination) for differences by ethnicity or race. OBJECTIVE To provide a descriptive illustration of changes in epigenetic age acceleration across childhood and adolescence among an ethnically and racially diverse sample of youths. DESIGN, SETTING, AND PARTICIPANTS This cohort study leveraged longitudinal data on a large sample of youths from low-income households in 20 large urban US cities who provided repeated assessments of saliva tissue samples at ages 9 and 15 years for DNA methylation analysis. Of 4898 youths from the Future of Families and Child Well-Being study, an ongoing study that oversampled children born to unmarried parents from 1998 to 2000, 2039 were included in the present analysis, as these youths had salivary DNA methylation data assayed and publicly available. Analyses were conducted from March 2023 to June 2024. EXPOSURES Racialized intrusive encounters with police (eg, stop and frisk and racial slurs). MAIN OUTCOMES AND MEASURES Analyses were conducted to examine longitudinal changes in salivary epigenetic age acceleration over time, whether such changes varied across ethnically and racially diverse groups of youths, and whether police intrusion was associated with variation across ethnic and racial groups. RESULTS Among 2039 youths (mean [SD] age at baseline, 9.27 [0.38] years; 1023 [50%] male and 1016 [50%] female; 917 [45%] Black, 430 [21%] Hispanic or Latino, 351 [17%] White, and 341 [17%] other, including multiple races and self-identified other) with salivary epigenetic clocks at 9 and 15 years of age, longitudinal results showed that White youths exhibited less accelerated epigenetic aging over time than did Black and Hispanic or Latino youths and those reporting other or multiple races or ethnicities from ages 9 to 15 years, particularly in the Hannum (B, 1.54; 95% CI, 0.36-2.18), GrimAge (B, 1.31; 95% CI, 0.68-1.97), and DunedinPACE epigenetic clocks (B, 0.27; 95% CI, 0.11-0.44). Across these clocks and the PhenoAge clock, police intrusion was associated with Black youths’ more accelerated epigenetic aging (Hannum: B, 0.11; 95% CI, 0.03-0.23; GrimAge: B, 0.09; 95% CI, 0.03-0.18; PhenoAge: B, 0.08; 95% CI, 0.02-0.18; DunedinPACE: B, 0.01; 95% CI, 0.01-0.03). CONCLUSIONS AND RELEVANCE The transition from childhood to adolescence may represent a sensitive developmental period when racism can have long-term deleterious impacts on healthy human development across the life span. Future research should build on the present study and interrogate which social regularities and policies may be perpetuating discrimination against ethnically and racially minoritized adolescents.