Comorbidity of anxiety disorders in a multicenter anxiety study.

From 11 sites in New England and Missouri, 711 patients with > or = one of five index anxiety disorders were recruited onto a longitudinal study in which they were interviewed every 6 months regarding symptoms, course, and treatments received. Of the five disorders studied, panic disorder without agoraphobia was the disorder most often found as a sole diagnosis and generalized anxiety disorder (GAD) was least often found alone, both as lifetime diagnoses or when restricted to cases active at intake. Panic disorder with agoraphobia and agoraphobia without history of panic disorder (AWOPD) had three specific diagnoses with which they were frequently comorbid: social phobia, simple phobia, and GAD. AWOPD, social phobia, and GAD were frequently found in the presence of each other. It is possible that the experience of anxiety due to any syndromal cause may decrease the threshold for an individual to experience other anxiety symptoms or disorders. Clinicians should be aware of these patterns of comorbidity in order to formulate accurate differential diagnoses and prescribe treatments in a rational manner.