The switch mechanism in periodic catatonia and manic-depressive disorder.

Both in periodic catatonia and in manic-depressive disorders sudden switches occur in behavior, in the autonomic nervous system and in the catecholamine metabolism during the transition from interval or depression into catatonia or mania. Both the manic and the catatonic attacks seem to be superimposed on the basic depressive or schizophrenic illnesses. The attacks can be counteracted or suppressed by psychotropic drugs such as alpha-methyldopa, disulfiram, reserpine, haloperidol or chloropromazine which interfere with the catecholamine metabolism or their receptor sites. The involvement of the catecholamines may however be secondary to primary defects in the thyroid, the hypothalamus or the limbic system. The strict periodicity in periodic catatonia points to an accumulation of some active metabolite which may be produced centrally during the interval. At a certain level it may trigger the switch-mechanism and then be reduced during the catatonic phase. In periodic catatonia both the basic schizophrenic disease as well as the periodic manifestations are compensated by thyroxine-thyroid treatment.