Examining the epigenetic mechanisms of childhood adversity and sensitive periods: a gene set-based approach

Abstract

BackgroundSensitive periods are developmental stages of heightened plasticity when exposure to childhood adversity may exert lasting impacts. A few biological pathways are known to play key roles in regulating sensitive period plasticity across brain development. Epigenetic mechanisms including DNA methylation (DNAm) may provide a means through which life experiences during sensitive periods induce long-term biological changes. In the current study, we investigated the possibility that adversity during sensitive periods led to DNAm changes in genes that regulate the timing and duration of sensitive periods in development. MethodsUsing childhood adversity data and genome-wide DNAm profiles from the Avon Longitudinal Study of Parents and Children (n=785), we summarized DNAm variation of CpG sites in the promoters of genes regulating sensitive periods with the first two principal components (PCs). DNAm summaries were calculated for genes regulating sensitive period opening (ngenes=15), closing (ngenes=36), and expression/duration (ngenes=8). We then performed linear discriminant analysis to test associations between these DNAm summaries and the timing of exposure to seven types of adversity. ResultsSexual or physical abuse and financial hardship during middle childhood (6-7 years) were associated with DNAm of genes regulating the onset and duration of sensitive periods. Sensitivity analyses assessing the presence of any exposure before age 7 and a composite measure of adversity yielded fewer signals, highlighting the importance of accounting for timing and adversity type. ConclusionsWith our novel gene set-based approach, we have uncovered suggestive evidence that epigenetic regulation of developmental plasticity may be affected by early life adversity. The complementarity of our gene-level view of the epigenome to the more common and granular epigenome-wide association study may yield novel mechanistic insights not only for adversity but also for other exposures and outcomes.