[Psychotic depression. 1. Classification, etio-pathophysiology, epidemiology, sympatomatology, diagnosis].

The term "depression" is used to describe a normal mood, a medical symptom, and a collection of psychiatric symptoms. As a normal mood, depression is a common human reaction to a significant loss; as a medical term, it is also used to describe the sadness seen in patients who have other severe medical and psychiatric disorders. Most often, however, "depression" refers to a group of psychiatric syndromes or illnesses with well defined symptoms only one of which is sadness. Depression syndromes are probably universal. There are accounts of depressive illness throughout history from almost every human society. The universality of depressive illness is also reflected in the frequency of depression as a theme of the world's great literature. Studies of the biochemical correlates of psychotic depression have focused on two major hypotheses. The first proposes that affective disorders result from functional changes in the central noradrenergic systems. The second postulates that the primary abnormality is in central serotonergic pathways. These two hypotheses are supported by the pharmacological effects of antidepressant drugs.