Co-morbidity and depression among the anxiety disorders. Issues in diagnosis and classification.

One hundred twenty-six patients presenting at an anxiety disorders research clinic were administered a structured interview. Diagnoses were made on the basis of DSM-III criteria but without regard to current exclusionary systems within DSM-III. Rather, clinicians decided whether anxiety and depressive symptoms that met DSM-III criteria for additional diagnoses were associated features of the presenting problem or represented an independent coexisting complication. Diagnoses and accompanying psychometric data delineated groups of patients with somewhat different clinical and psychometric characteristics. But additional anxiety and depressive diagnoses were required in a number of cases. Anxiety states almost always required additional diagnoses whereas for the phobic disorders additional diagnoses occurred less frequently. Simple and social phobia were the most frequent additional diagnoses, but depression was more strongly associated with some anxiety disorders, specifically obsessive-compulsive disorder. In view of the treatment implications of comorbidity, establishing the functional relationships among anxiety symptoms without regard to exclusionary systems would seem important in both clinical and research settings.