Effect of neuroleptic drugs on platelet monoamine oxidase in psychiatric patients.

The authors determined the platelet MAO activity of 57 psychotic patients after a placebo period and after 3-65 days of neuroleptic treatment. Platelet MAO activity significantly decreased in both men and women after neuroleptic treatment. The platelet MAO activity of neuroleptic-treated schizophrenic women was significantly less than that of drug-free schizophrenic women, who did not differ from normal women. There were trends in the same direction for the schizophrenic men. Previous studies that reported lower platelet MAO activity in neuroleptic-treated schizophrenic patients than in normal controls may have been influenced by this neuroleptic effect.