[Biological perturbations in affective disorders in man]

The biological evidence in affective disorders is perhaps strongest in the genetic field, where twin studies demonstrate very different concordance rates for monozygotic and dizygotic twins, 60-70 and 10-20 per cent, respectively. Physiological disturbances include low saliva production and reduced REM-latency. Biochemical findings have been many, but few have stood the test of time. In a majority of patients one or more amines or amine-metabolites are reduced in cerebrospinal fluid. The hypophyseal-hypothalamic axis is also involved in affective disorders. In depression, steroid levels are high, particularly due to continued high secretion rates at night, indicating a disturbance of diurnal rhythms. Further support for a hypothalamic dysfunction of the adrenal feedback, system comes from the finding of the lack of suppressibility of plasma steroid levels after dexamethasone in depressed patients. The reduction of growth hormone response to hypoglycemia and of thyrotrophin (TSH) response to thyrotrophin releasing hormone (TRH) lend further support to a more general theory of disturbed feedback mechanisms in affective disorders. The essential, unsolved problem is whether the physiological and biochemical disturbances are causes or consequences of the affective disorders.