Distinguishing emotional numbing symptoms of posttraumatic stress disorder from major depressive disorder

Emotional numbing symptoms are a core aspect of posttraumatic stress disorder (PTSD). Since the initial characterization of PTSD in DSM-III, emotional numbing symptoms have been revised and grouped under different symptom clusters (avoidance in DSM-IV, negative alterations in cognitions, and mood in DSM-5). Previous studies have found emotional numbing symptoms to be associated with greater PTSD severity, functional impairment, and worse treatment outcomes. Although considered an important feature, some argue that emotional numbing symptoms may simply reflect the manifestation of major depressive disorder (MDD) symptoms rather than be an inherent part of the PTSD phenotype. Here, we evaluated this question using two different data sets (N1 = 142; CAPS-5, N2 = 163; CAPS-4) of trauma-exposed individuals. First, we evaluated the unique variance of emotional numbing explained by diagnosis as binary variables (i.e., having PTSD, MDD, or both) and the severity of symptoms. Second, we examined the relative importance of each PTSD symptom in relation to emotional numbing symptoms. Results revealed that PTSD had a distinct contribution to the variance explaining emotional numbing symptoms above and beyond MDD. These findings suggest that emotional numbing should not be conceptualized as a simple manifestation of MDD symptoms. Rather, this symptom cluster may be a unique feature of PTSD that should be addressed within the context of trauma.