Socially stratified DNA-methylation profiles are associated with disparities in child and adolescent mental health
Authors: Raffington L. , Tanksley P. , Vinnik L. , Sabhlok A. , Patterson M.W. , Mallard T. , Malanchini M. , Ayorech Z. , Tucker-Drob E.M. , Harden K.P. 
Published: September 2021

AbstractImportanceEconomic and racial inequality is linked to disparities in children’s mental health. Biomarkers that reflect these social disparities are lacking.ObjectiveWe examined the hypothesis that salivary DNA-methylation patterns of higher inflammation and faster pace of biological aging are economically, racially and ethnically stratified and are associated with child mental health.DesignThe Texas Twin Project is an on-going, observational, longitudinal study that began in May 2012. Analyses were preregistered on May 7, 2021, and completed on August 23, 2021.SettingThe population-based study identified and recruited participants from public school rosters in the greater Austin area.ParticipantsParticipants in the analytic data set included all participants that agreed to contribute DNA samples and whose samples were assayed by January 2021.ExposuresFamily- and neighborhood-level socioeconomic inequality, racial and ethnic identities (White, Latinx, Black, Asian).Main Measure(s)Environmental exposures were analyzed in relation to salivary DNA- methylation profiles of higher inflammation (DNAm-CRP) and faster pace of biological aging (DunedinPoAm). Child internalizing problems, attention problems, aggression, rule-breaking, ADHD, oppositional defiant disorder, and conduct disorder were measured using parent-reports and self-reports on abbreviated versions of the Achenbach Child Behavior Checklist and Conners 3.The hypotheses being tested were formulated after data collection of the present data freeze and were pre-registered prior to analyses being conducted.ResultsIn a sample of N=1,183 8-to-19-year-olds (609 female, age M=13.38y), children’s salivary DNA-methylation profiles and psychiatric symptoms differed by socioeconomic conditions, race and ethnicity. Children with more parent-reported internalizing symptoms had higher DNAm-CRP (r=0.15, 95% CI=0.05 to 0.25, P=0.004) and DunedinPoAm (r=0.15, CI=0.05 to 0.25, P=0.002), and children with more parent-reported aggression problems had higher DNAm-CRP (r=0.17, CI=0.04 to 0.31, P=0.013). DNAm-CRP partially mediated advantage of higher family socioeconomic status (16% of total effect) and White racial identity (12% of total effect) on reduced internalizing symptoms. DunedinPoAm also partially mediated advantage of White racial identity on internalizing (19% of total effect).Conclusions and RelevanceSocioeconomic and racial inequality are visible in children’s epigenetic profiles of inflammation and the rate of biological aging in a manner that is tied to social disparities in mental health.Key PointsQuestionWe examined whether salivary DNA-methylation profiles are socially stratified and associated with child mental health.FindingsIn this preregistered, cross-sectional observational study of 1,183 children and adolescents, socioeconomic, racial, and ethnic disparities in mental health were associated with salivary DNA-methylation profiles of inflammation and the pace of biological aging.MeaningDNA-methylation biomarkers hold promise as tools to quantify the biological impact of socioeconomic inequality and being racially minoritized in a manner that is tied to social disparities in mental health.