[The future of the concept of depression].

The history of the concept of depression is briefly reviewed. First described under the name of melancholia as a delusional state, then, since Esquirol, as a primary mood disorder, it was subdivided by Kraepelin in diseases characterised by an hypothetical etiology and is considered, since 1980, as a syndrome with many sub-varieties. The nature of the three possible models is discussed. The first two, until now used, which considered depression either as a disease or as a syndrome, are categorical. The first has been provisorily abandoned, due to the insufficiency of scientific proofs about the etio-pathogeny; the second, despite its growing complexity, is obviously not satisfactory. The third model, dimensional, which attracts a growing attention in other field of psychiatric nosology, offers for the time being a possible alternative.