Identifying differential interactions of traumatic experiences with genetic risk for posttraumatic stress disorder

Background: Posttraumatic stress disorder (PTSD) occurs following traumatic experiences, but not everyone who experiences trauma develops PTSD. Genetic factors play an important role in shaping how individuals respond to trauma, a form of gene-environment interaction. An open question in PTSD genetics research is the extent to which gene-environment interactions vary across specific traumas. Objective: We aimed to compare gene-environment interaction effects across a broad range of self-reported traumatic experiences across the lifespan. Method: We analysed existing data from two large UK cohorts: the UK Biobank and GLAD-EDGI-COPING (N=144,702). PTSD symptoms were assessed using the six-item abbreviated PTSD Checklist. We examined eleven self-reported trauma exposures, including five childhood traumas and six adulthood traumas. We conducted gene-environment interaction analyses for each trauma at three levels of genetic specificity: polygenic risk scores, specific genes, and specific genetic variants. Results: Childhood traumas had stronger associations with PTSD symptoms and greater gene-environment interactions than adulthood traumas on average. Childhood emotional and physical neglect also had gene-environment greater interactions than childhood abuse. Interaction patterns varied across genes and variants, with several leading PTSD-associated genes (e.g. ANAPC, FAM120A, SGCD ) having particularly great interactions with certain traumas. Several genes ( DTX4, PSMD12, TYW3, ZNF660 ) demonstrated consistently stronger interactions with all childhood or all adulthood traumas. Differences in gene-environment interactions across traumas were not explained by variation in exposure rates, associations with PTSD, or gene-environment correlations. Conclusions: Genetic influences on PTSD risk vary by trauma type and are most pronounced for childhood traumas. To account for the moderating role of trauma type, genetic research on PTSD should incorporate detailed trauma exposure information.