Rethinking the mood and anxiety disorders: a quantitative hierarchical model for DSM-V.

The fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 1994) groups disorders into diagnostic classes on the basis of the subjective criterion of "shared phenomenological features." There are now sufficient data to eliminate this rational system and replace it with an empirically based structure that reflects the actual similarities among disorders. The existing structural evidence establishes that the mood and anxiety disorders should be collapsed together into an overarching class of emotional disorders, which can be decomposed into 3 subclasses: the bipolar disorders (bipolar I, bipolar II, cyclothymia), the distress disorders (major depression, dysthymic disorder, generalized anxiety disorder, posttraumatic stress disorder), and the fear disorders (panic disorder, agoraphobia, social phobia, specific phobia). The optimal placement of other syndromes (e.g., obsessive-compulsive disorder) needs to be clarified in future research.