Epigenome-Wide Study of Posttraumatic Stress Disorder Symptom Severity in a Treatment-Seeking Adolescent Sample

Emerging research has demonstrated that psychosocial trauma exposure may elicit epigenetic changes, with downstream effects on the transcriptional regulation of genes. Epigenome-wide association studies (EWAS) offer an agnostic approach to examine DNA methylation (DNAm) associations and are a valuable tool to aid in the identification of biological pathways involved in posttraumatic stress disorder (PTSD). This study represents the first EWAS of PTSD in an adolescent sample, an important group given the significance of this developmental period regarding both DNAm changes and PTSD risk. The sample (n = 39, M age = 15.41 years, SD = 1.27, 84.6% female) comprised adolescents who experienced interpersonal trauma and were enrolled in a treatment study. Participants were assessed using the UCLA PTSD Reaction Index for DSM-IV-Adolescent Version and provided a blood sample at baseline. Genomic DNA was isolated from whole blood and assayed using the Illumina Infinium MethylationEPIC BeadChip. The primary analysis estimated the associations among individual CpG sites and PTSD symptom scores. Of the 793,575 screened probes tested, two were significant at a false discovery rate (FDR) < 10%. Hypomethylation of both sites was associated with increased PTSD symptom scores. Analysis of differentially methylated regions (DMR) identified a DMR associated with PTSD symptom scores at an FDR < 10%. Results from follow-up models are also discussed. Findings from this preliminary investigation suggest the importance of further research conducted in adolescent samples. The analytic pipeline and results are documented for use in future meta-analytic work as more such samples become available.