Poor outcome and low platelet MAO activity in chronic schizophrenia.

Platelet monoamine oxidase (MAO) activity was significantly lower among 21 chronic schizophrenic patients, 19 of whom were receiving stable doses of antipsychotic medication, than among 16 control subjects. Poor ego functioning and poor outcome were significantly correlated with low MAO activity; current dose of major tranquilizer was negatively but not significantly correlated. The degree of psychopathology, rather than presence or absence of specific symptom constellations, was the significant characteristic of patients with low enzyme levels. This finding is in accordance with those of earlier studies of schizophrenic patients as well as with recent findings in nonschizophrenic samples.