Comorbid Major Depressive Disorder in Cognitive-Behavior Group Treatment for Social Anxiety Disorder: An Examination of Processes of Symptom Change

Individuals with social anxiety disorder (SAD) typically have elevated depressive symptoms and approximately 50% also meet criteria for major depressive disorder (MDD; Beesdo et al., 2007). In the present study, we examined the relationship between social anxiety and depressive symptoms during cognitivebehavior group treatment (CBGT) for SAD. Specifically, we compared individuals with SAD and comorbid MDD and individuals with SAD without MDD to examine the role of MDD as a moderator of social anxiety–depression relationship. Participants were 90 individuals seeking treatment for SAD (36% were diagnosed with MDD), who completed self-report measures of social anxiety and depression every 2 weeks during CBGT. Lower level mediational modeling indicated that for individuals without MDD, a reciprocal relationship was observed in which changes in both social anxiety and depressive symptoms mediated changes in each other. However, changes in social anxiety explained all subsequent changes in depression, whereas changes in depression explained 11.26% of subsequent changes in social anxiety. For individuals with both SAD and MDD, neither social anxiety nor depression significantly mediated changes in each other. Our findings suggest that different processes of change occur for individuals with and without MDD and clinical implications of these findings are discussed.