[Biochemistry of depression]

1. In patients with endogenous depression a functional deficiency of noradrenalin and serotonin is presupposed. This hypothesis is based on examinations of the metabolites of these transmitter substances in the cerebrospinal fluid and in the urine. 2. Attempts to compensate the deficiency by means of precursors of the transmitter show a great variety of therapeutic effects. Possible metabolic regulations are discussed. 3. Changes of hormone metabolism are involved in the disease, these are discussed. 4. At present valid statements on the causes of a biochemical defect in depressive illness are not possible.