Defining melancholia: the primacy of psychomotor disturbance

OBJECTIVE: To argue that melancholia is a categorically distinct depressive condition, able to be differentiated from other depressive conditions by a neuropathological marker [observable psychomotor disturbance (PMD)] and having a differential response to various antidepressant treatments. METHOD: The above statements are addressed by review of a wide body of research, which identified observable PMD as the cardinal marker of melancholia and developed the CORE measure as a strategy for assessing PMD and its severity. Properties of the CORE measure, including reliability, validity and treatment prediction, are overviewed. RESULTS: A case is made for defining melancholia and a strategy for establishing its probability. CONCLUSION: Melancholia is positioned as a categorical entity capable of being circumscribed by its cardinal feature of PMD.