Validity and clinical utility of the current operational characterization of major depression

The operational definition of major depression has remained more or less the same in the past 40 years. An appraisal of currently available research data leads to the conclusion that further evidence is needed about (1) where to fix the boundary between cases and non-cases in order to improve the clinical utility of the diagnosis, (2) the validity and clinical utility of the construct of melancholia as a qualitatively distinct subtype of depression, and (3) the validity and clinical utility of a 'contextual' exclusion criterion. Furthermore, we need a more precise description of individual depressive symptoms, an exploration of the predictive value of these symptoms and of clusters of them, especially concerning clinical outcome and treatment response, and a clearer operationalization of the impairment criterion. © 2012 Institute of Psychiatry.