Associations Between Corporal Punishment and DNA Methylation in Stress Genes
Psychiatric disorders are highly prevalent, affecting 1 in 5 Americans and an estimated 49.7% of adolescents. Early life stress such as exposure to corporal punishment is commonly associated with psychiatric vulnerability. Corporal punishment has been associated with hypothalamic pituitary adrenal (HPA) axis dysregulation, a common endophenotype across many psychiatric disorders. Recent research suggests stress induced HPA dysregulation may occur through long lasting alterations in DNA methylation profiles of HPA regulatory genes. In the current study, we investigated the relationship between early corporal punishment and methylation of HPA genes in middle childhood with monozygotic (MZ) twins. We hypothesized that corporal punishment at 30 months is associated with methylation of HPA axis genes at 8 years. Our sample included 96 MZ twins (48 families; 51% male; 50% Non-Hispanic White, 14.6% Hispanic/Latinx, 8.3% African American, 4.2% Asian American), with a mean age of 8.5 years, drawn from the Arizona Twin Project. Questionnaire data from the twins’ caregivers included measures of parent punishment practices (HOME Infant/Toddler Short Form and Parental Responses to Child Misbehavior]). Methylation was quantified from buccal cells using the Infinium Methylation EPIC BeadChip. We extracted the first two principal components from % methylation of CpG sites near eight genes of interest after removing all sites with a <0.3 loading (all genes variance explained was > 40%). Next, we computed MZ difference scores in corporal punishment and methylation for linear regression analysis controlling for sex. We found spanking and punitive punishment at 30 months significantly predicted methylation of several HPA axis genes. These results suggest corporal punishment may have long lasting influence of DNA methylation and HPA function. The relationship between early life stress and psychiatric vulnerability has been long established. Perhaps elucidating the molecular consequences of early life stress can be used to inform best parenting practices. We are currently expanding these results with RNA expression and daily cortisol analyses.