The Underlying Role of Negative Affect in the Association between PTSD, Major Depressive Disorder, and Generalized Anxiety Disorder

Clinicians and researchers have found differential diagnosis to be difficult, particularly for conceptually similar disorders. One category of particular interest has been distress or internalizing disorders, theorized to be related via an underlying construct of generalized distress or negative affect. The present study attempted to address the comorbidity of three distress disorders - posttraumatic stress disorder (PTSD), major depressive disorder (MDD), and generalized anxiety disorder (GAD) - using latent analyses by controlling for the variance attributable to negative affect. The sample consisted of 265 trauma-exposed individuals who completed self-report measures of PTSD, MDD, GAD, and negative affect. Confirmatory factor analysis was used to test initial model fit. Next, the model was re-computed, controlling for negative affect by regressing negative affectivity at the item-level. Results indicated that a significant amount of variance within and between these diagnostic categories is attributable to negative affect at both the item- and factor-level. The hypothesis that MDD's non-somatic/affective factor and the GAD factor would have the highest attenuations in factor loadings after controlling for negative affect was supported. Therefore, negative affect significantly influences the co-occurrence of PTSD, MDD, and GAD clinically, emphasizing the need for transdiagnostic interventions for trauma victims.