Platelet monoamine oxidase activity in schizophrenia: a review of the data.

The authors review studies of platelet and white cell monoamine oxidase (MAO) activity in schizophrenic patients. The data on acute schizophrenic patients remain inconclusive. Review of 26 reports of chronic schizophrenic patients leaves little doubt, however, that there is a subgroup in which the enzyme activity is decreased. Despite the strong association of decreased MAO activity and chronic schizophrenia, the etiological relationship of low platelet MAO activity to schizophrenia has not been demonstrated. More complete diagnostic descriptions will shed light on precisely which patients have lowered MAO activity. Further metabolic investigations with such patients are needed to determine the physiological significance of this phenomenon.