DSM-IV depression with atypical features: is it valid?

Atypical features were incorporated into the American Psychiatric Association's Diagnostic and Statistical Manual, Fourth Edition (DSM-IV, 1994) as an illness specifier for major depression and dysthymia. The validity of depression with atypical features was supported by differences relative to depression with melancholic features in syndromal symptoms, course of illness, biology, family history, and treatment response. This paper reviews post-DSM-IV literature relevant to the validity of depression with atypical features. Most studies support the pre-DSM-IV findings. Again, course of illness, biological, family, and treatment differences are shown between melancholia and depression with atypical features. Several biologic studies report nondepressed controls have mean values between depressed subjects having atypical features and other depressed patients. This suggests atypical depression is a distinct depressive group rather than a milder form of melancholia. In addition, some studies show distinctions between depressed subjects with atypical features and those having neither atypical nor melancholic features. As depression with atypical features separates not only from melancholia but also from other depressed groups and controls over a range of meaningful distinctions, we conclude it is a valid clinical syndrome, useful both heuristically and in driving treatment decisions.