Blood monoamine oxidases and CT scans in subgroups of chronic schizophrenics

An assay method for monoamine oxidase (MAO) employing whole blood samples is described. With this method, whole blood samples collected from three subgroups of chronic schizophrenic patients were assayed directly for MAOb activity without the need for prior isolation of platelets. Our results support previous findings from assays with platelets that chronic paranoid schizophrenics have decreased blood MAOb activity compared to chronic non-paranoid schizophrenics or normal controls. The level of MAOb activity in the blood of the non-paranoid schizophrenics was also linearly correlated with ventricular size (i.e. ventricular brain ratio, VBR) as determined by CT scan analysis. This correlation was not true for the paranoid group. The MAOb data in conjunction with the VBR data were sufficient to divide without overlap our schizophrenic patient population into two clinically defined subgroups.