[The concept of depression. Evolution of thoughts from Kraepelin until today (author's transl)].

Our concept of depression have been profondly modified during these last decennies. The work of Kraepelin keeps an interest more than historical. By proposing a medical model for thymic troubles, he has opened the avenue for genetic and biochemical research which will confirm or not the nosology based on clinical investigations. Other models have been proposed for affective troubles : psychodynamic, ethological and experimental models. It is not yet possible to make a synthesis integrating psychological and biological parameters.