Melancholia: An Attempt at Definition Based on a Review of Empirical Data.

We sought to identify clinical features that best discriminate melancholia from nonmelancholic depressive conditions. An extensive review of studies using latent factor models that identified a melancholic depression dimension/factor was undertaken. Clinical variables extracted from these studies were analyzed in terms of their contribution to a diagnosis of melancholia and their consistency across studies. Psychomotor retardation and mood nonreactivity were the most relevant clinical features for the identification of melancholic depressions. Other clinical features commonly described as weighted to melancholia, such as anhedonia, psychomotor agitation, late insomnia, or appetite/weight loss, seemed less useful in distinguishing these subtypes of depression. Study results are considered in relation to the potential limitations of current operational definitions of melancholia, and how symptom sets could be modified.