Gros DF, Price M, Magruder KM, Frueh BC.
Psychiatry Res. 2012 Mar 2. [Epub ahead of print]

Abstract
Over the past decade there has been consistent criticism of the diagnostic criteria of posttraumatic stress disorder (PTSD) because of its high comorbidity with other mental disorders. Part of the problem surrounding PTSD may be related to the heterogeneity of its symptoms. In fact, recent research has identified a subset of PTSD symptoms, including symptoms of numbing and dysphoria, that may explain much of the overlap between PTSD and major depressive disorder (MDD). The present study sought to extend prior work by investigating the various subsets of PTSD symptoms in individuals from all four diagnostic combinations of PTSD and MDD (no MDD-PTSD, MDD-only, PTSD-only, and comorbid MDD-PTSD). Consenting participants completed diagnostic interviews and were categorized into the four groups. Based on responses to a self-report measure of PTSD symptoms, participants with no MDD-PTSD reported the least severe symptoms while the participants with comorbid MDD-PTSD reported the most severe symptoms. Interesting, participants in the MDD-only and PTSD-only groups consistently reported similar scores across all PTSD symptom scales. These findings further highlight the problematic diagnostic criteria and comorbidity in PTSD and emphasize the need to incorporate transdiagnostic treatment practices that focus on the overlapping symptoms, rather than specific diagnostic categories.