ARE PARANOID SCHIZOPHRENICS BIOLOGICALLY DIFFERENT FROM OTHER SCHIZOPHRENICS

Two studies were undertaken to verify the presence of lowered platelet monoamine oxidase activity in chronic schizophrenia. In the first study, a retrospective chart analysis, the mean platelet activity of patients with chronic schizophrenia (7.73±0.64 nmol of benzylaldehyde product per 108 platelets per hour [S.E.M.]) differed significantly from that of normal controls (12.13±0.2, P<0.001). Chronic paranoid schizophrenics (4.81 ±0.46) differed significantly from chronic nonparanoid schizophrenics (8.6±0.75, P<0.03). A separate prospective study confirmed significantly lower values for monoamine oxidase activity in chronic schizophrenic patients diagnosed as paranoid (5.97±1.17) or as having secondary paranoid features (6.28±0.71) as compared to chronic nonparanoid schizophrenics (9.81 ±0.87, P<0.001). Chronic paranoid schizophrenia may be a separate disorder from the other chronic forms of schizophrenia, and this difference may be related, at least in part, to biochemical characteristics. (N Engl J Med 298:61–66, 1978) MONOAMINE oxidase (MAO) has been the focus of several studies seeking to link biochemical and psychologic phenomena. It is a crucial enzyme involved in the degradation of biogenic amines that are important to the regulation of behavior, and is very accessible for measurement in the blood platelets of man. Platelet MAO activity has been found to be reduced in patients with a number of psychiatric disorders: patients with bipolar affective disorders, alcoholism and chronic schizophrenia.1 2 3 4 5 6 A great deal of variability in platelet MAO activity exists from person to person, and appears, at least in part, to be of genetic origin. © 1978, Massachusetts Medical Society. All rights reserved.