Atypical depression: useful concept, but it's time to revise the DSM-IV criteria.

Stewart et al (2009) have outlined the evidence in support of the validity of the DSM-IV definition of the 'With Atypical Features' episode specifier. Although recognizing the historical significance and clinical utility of the concept of atypical depression, this article takes issue with the DSM-IV criteria. It is concluded that mood reactivity, the A or obligative criterion, is neither significantly associated with the other symptomatic criteria nor useful to diagnose atypical depression, and thus should be eliminated. Problems with operationalization, specification, and reliability of ratings of the diagnostic criteria further limit validity. Despite these limitations in classification, many of the features associated with atypical depression are linked to an early onset of affective illness, including trait-like interpersonal sensitivity, comorbid social anxiety and agoraphobia, a history of childhood physical or sexual trauma, and indicators of the 'soft' side of the bipolar spectrum. Neurophysiologic studies also suggest that chronic, early-onset atypical depressions differ from both melancholia and normality. Re-analyses of the Columbia group's seminal studies suggest that preferential response to phenelzine vs imipramine--arguably the strongest validator of atypical depression--similarly appears to be limited to patients with chronic, early-onset syndromes. The criteria for atypical depression need to be revised in DSM-V, including sharpening the operational definitions for the specific symptoms. The importance of age of onset and comorbid anxiety warrant further study. Research examining the validity of a subform of atypical depression characterized by trait-like interpersonal sensitivity and a chronic, early-onset course may further enhance the clinical utility of the DSM-V classification.