Diagnostic and symptom distinguishability of generalized anxiety disorder and obsessive-compulsive disorder

In light of recent observations (e.g., DSM-IV Task Force) of apparent similarities between features of generalized anxiety disorder (GAD) and obsessive-compulsive disorder (OCD), particularly chronic worry and obsessions, the present study examined the extent to which the two disorders were distinguishable at the diagnostic level and by self-report questionnaires. Subjects were 46 patients with GAD and 31 patients with OCD diagnosed via the Anxiety Disorders Interview Schedule-Revised (ADIS-R). Of 41 patients who received two independent ADIS-Rs, in no instance did one interviewer assign a principal diagnosis of GAD and the other, OCD. Furthermore, analyses of diagnostic comorbidity indicated that GAD and OCD infrequently co-occurred. Patients with GAD and patients with OCD were reliably distinguished by ADIS-R screening items and self-report measures of the essential features of each disorder (e.g., presence of uncontrollable worry, obsessions), but did not differ on associated features (e.g., anxiety, depression). Correlational analyses using a large sample (N=533) revealed that, despite having reliable shared variance, measures of worry and obsessions evidenced considerable differentiation as well.