DNA methylation mediates the link between adversity and depressive symptoms

Experiences of childhood adversity can double the risk for depression. Although the mechanisms underlying this relationship remain unclear, DNA methylation (DNAm) has emerged as a potential pathway to explain the link between adversity and depression. We thus investigated whether epigenome-wide DNAm statistically mediates the association between childhood adversity and adolescent depressive symptoms. Specifically, we performed epigenome-wide mediation analyses to investigate the role of blood-based DNAm (age 7 years) in linking seven types of adversity (ages 0–7 years) to depressive symptoms (age 10.6 years). Primary analyses were conducted in the Avon Longitudinal Study of Parents and Children and replicated in the Future of Families and Child Wellbeing Study and Generation R Study. We identified 70 cytosine–guanine dinucleotides (CpGs) that mediated 10–73% of the correlation between adversity and depressive symptoms, with DNAm differences at 39 of these CpGs showing protective effects. Our findings suggest DNAm reflects a biological pathway linking childhood adversity to depression and a potential mechanism towards resilience. Using epigenome-wide mediation analyses to investigate DNA methylation as a path between adversity and depression, the authors found 31 cytosine–guanine dinucleotides (CpGs) associated with risk and 39 CpGs associated with protective effects.