[Contribution of biology to nosology of depressive states. Neurochemical, endocrine and genetic factors (author's transl)].

Genetic factors have been evidenced in the etiology of manic-depressive syndromes through twins, morbidity risk studies, linkage studies with genetic markers such as color blindness and the Xga blood group, as well as through adoption studies. Most genetic studies indicate that there is a genetic and biological heterogeneity in manic-depressive illness. Among these manic-depressive syndromes, one group is consistent with a dominant X-linked transmission of the disease. From the neurochemical point of view, most investigators emphasize the importance of cerebral neurotransmitter substances such as catecholamines and indolamines in the pathogenesis of bipolar depressive states. According with this hypothesis, depression is associated with a functional deficit in brain monoamines while mania may be due to an hyperproduction of monoamines. These neuropharmacological studies are of importance because they also have neuroendocrine implications. Some pituitary hormones are secreted under the control of brain monoamines, and they are also implicated in the pathogenesis of depressive states.