Depressive comorbidity of panic, social phobic, and obsessive-compulsive disorders re-examined: is there a bipolar II connection?

Utilizing the DSM-III-R schema, we have investigated lifetime comorbidity between panic disorder with or without agoraphobia (PD), social phobia (SP) and obsessive-compulsive disorder (OCD) on the one hand, and mood disorder on the other. Compared with PD, the results for SP and OCD showed significantly higher numbers of comorbid anxiety and mood disorders. In addition, SP and OCD were significantly more likely to cooccur with each other than with PD. The complexity of these comorbid patterns is underscored by the finding of significantly higher numbers of anxiety disorders in those with lifetime comorbidity with bipolar (especially bipolar II) disorder. We conclude that the comorbidity between anxiety and mood disorders - conventionally conceived as the relationship between anxiety and unipolar depressive states -- might very well extend into the domain of bipolar spectrum disorders in a subset of these disorders. Among the latter, the spontaneous or antidepressant-induced switches into brief disinhibited (hypomanic) behavior can be conceptualized to lie on a dimensional continuum with the temperamental inhibition (or constraint) underlying the anxiety disorders under discussion. These findings and theoretical considerations have important therapeutic implications.