Why do trauma survivors become depressed? Testing the behavioral model of depression in a nationally representative sample.

Despite accumulated evidence linking trauma exposure to major depressive disorder (MDD), there is limited understanding as to why some trauma survivors subsequently develop MDD. The behavioral model of depression points to a negative reinforcement cycle of trauma-related avoidance and depressed mood, but no study has evaluated this framework in trauma survivors. This study tested the hypothesis that traumatic stress symptom-related interference with daily activities and with relationships and self-medicating traumatic stress symptoms with alcohol and with drugs would predict MDD onset in a nationally representative sample after controlling for established risk factors. Data were drawn from Waves 1 and 2 of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) using two samples: adults reporting lifetime trauma exposure but no history of MDD at Wave 1 (n = 8301) and a subset of those participants who met criteria for lifetime PTSD prior to Wave 1 (n = 1055). Younger age, female gender, a greater number of different trauma types, traumatic stress-related interference with daily activities, and self-medicating traumatic stress symptoms with alcohol significantly predicted MDD onset in both groups. Findings underscore the role of traumatic stress-related interference and self-medication in the development of MDD.