Mapping network connectivity among symptoms of social anxiety and comorbid depression in people with social anxiety disorder

Background: Social anxiety disorder (SAD) and depressive symptoms often covary. Yet, uncertainty still abounds vis-a-vis the individual symptom-to-symptom associations between these two disorders. Inspired by the network approach to psychopathology that conceptualizes comorbidity as a natural consequence arising from bridge symptoms that can transmit activation from one disorder to the other, we applied network analytic methods to characterize the associations among core symptoms of SAD-i.e. fear and avoidance of social situations-and comorbid depressive symptoms among 174 individuals with DSM-IV-TR criteria for SAD. Methods: We first explored the general structure of these symptoms by estimating a regularized partial correlation network using the graphical LASSO algorithm. Then, we specifically focused on the symptoms' importance and influence. Of critical interest was the estimation of the unique influence of each symptom from one disorder to all symptoms of the other disorder using a new metric called bridge expected influence. Results: The graphical LASSO revealed several cross-associations between SAD and comorbid depression. For each disorder, symptoms exhibiting the strongest cross-association with the other disorder were identified. Limitations: Given our cross-sectional data, our findings can only suggest hypotheses about cause-effect relationships. Conclusions: This study adds to a small but growing empirical literature revealing that the co-occurrence between two disorders is best portrayed as sets of symptom-to-symptom connections. As some individual symptoms show differential association in the co-occurrence between SAD and depression, those symptoms may be valuable targets for future research and treatment.