Classification of depression by grade of membership: a confirmation study.

One hundred and thirty out-patients with depression were studied by grade of membership multivariate (GOM) analysis. Five depressive types were generated. Pure Type I represented a mild form of melancholia in older, stable males, who showed a modest drug response. Pure Type II included obsessive-anxious symptoms in older patients who responded well to an MAOI drug, but poorly to placebo. Pure Type III was a mildly symptomatic form of depression which responded well to placebo. Pure Type IV included features of agitation, mood worsening later in the day, anorexia and depersonalization; it was commonly precipitated by external stress and MAOI treatment was more effective than placebo. In Pure Type V depression, patients were mostly younger females with high levels of symptomatology, atypical vegetative symptoms, unstable life-styles, disadvantaged backgrounds and a poor response to MAOI and placebo. These results resemble in many ways our earlier GOM study of depression, as well as other multivariate studies of depression in the literature.