A Second Look at Comorbidity in Victims of Trauma: the Posttraumatic Stress Disorder-major Depression Connection

Background: We examine whether traumatic events increase the risk for major depression independent of their effects on posttraumatic stress disorder (PTSD).

Methods: Data come from the Epidemiologic Study of Young Adults in southeast Michigan (N = 1007). Retrospective and prospective data were used to estimate the risk of major depression in persons with PTSD and persons exposed to trauma with no PTSD, compared with persons who did not experience a trauma. National Comorbidity Survey data were used to evaluate the influence of trauma type.

Results: In the retrospective lifetime data, hazard ratios were, for first-onset major depression in exposed persons with PTSD, 2.8 and, in exposed persons with no PTSD, 1.3 (not significant), as compared with persons who were not exposed. Corresponding estimates from the prospective data were 11.7 and 1.4 (not significant). The difference in the risk for depression associated with PTSD versus exposure without PTSD is unlikely to be due to differences in trauma type.

Conclusions: The findings of a markedly increased risk for major depression in persons with PTSD, but not in exposed persons without PTSD, do not support the hypothesis that PTSD and major depression in trauma victims are influenced by separate vulnerabilities.