Clarifying the association between adverse childhood experiences and postdeployment posttraumatic stress disorder symptom severity: A meta-analysis and large-sample investigation.

We report on two studies designed to shed light on the association between adverse childhood experiences (ACEs) and posttraumatic stress disorder (PTSD) symptom severity in military personnel. In particular, we examined the evidence for both additive and multiplicative associations between ACEs and combat exposure in predicting PTSD symptom severity. Study 1 was a meta-analysis of 50 samples (N > 50,000), and we found evidence for a moderate linear association between ACEs and PTSD symptom severity, ρ = .24. We also found that ACEs explained substantial variance in PTSD symptom severity after controlling for combat exposure, ΔR = .048. In Study 2, which is preregistered, we relied on a large sample of combat-deployed U.S. soldiers (N > 6,000) to examine evidence of a multiplicative association between ACEs and combat exposure in predicting PTSD symptom severity. In line with theoretical arguments that individuals who have experienced childhood trauma are more vulnerable to subsequent trauma exposure, we found a weak but meaningful interaction effect, ΔR = .00, p < .001, between ACEs and deployment-related traumatic events in the prediction of PTSD symptom severity. Implications for clinical applications and future research are discussed.