Platelet monoamine oxidase in chronic schizophrenic patients.

The authors investigated platelet monoamine (MAO) activity in 40 chronic schizophrenic patients, 55 normal control subjects, and 16 hospitalized control subjects. The mean platelet MAO activity for the chronic schizophrenic patients was significantly lower than the mean in either control group. There were no significant differences between the mean platelet MAO activities in 21 chronic paranoid schizophrenic patients compared with 18 chronic undifferentiated schizophrenic patients.