27 - DEVELOPMENTAL TIMING OF EXPOSURE TO ADVERSITY PREDICTS DNA METHYLATION IN LATE CHILDHOOD MORE THAN RECENCY OR ACCUMULATION OF EXPOSURE

Abstract

Background Exposure to “early life” adversity (e.g., in the first two decades of life) is known to predict DNA methylation (DNAm). However, few studies have investigated whether adversity has time-dependent effects based on the age at exposure. Methods Data for our prospective study came from the Accessible Resource for Integrated Epigenomics Studies (ARIES), a subsample of 1,018 mother-child pairs from the Avon Longitudinal Study of Parents and Children (ALSPAC). Results After covariate and cell-type adjustment and Bonferroni correction for multiple testing, we identified 40 CpG sites that were differentially methylated following exposure to adversity. Nearly all of these loci (n=38) were related to adversity exposure in infancy. Financial stress, maternal psychopathology, and neighborhood disadvantage predicted the greatest number of epigenome-wide DNAm changes. Discussion These results suggest that the developmental timing of adversity explains more variability in DNAm than the accumulation or recency of exposure. Infancy appears to be a sensitive period when exposure to adversity predicts differential DNAm patterns.