Catalepsy induced by alpha-methyl-p-tyrosine and d-amphetamine: the rôle of catecholamine metabolism

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 10(8) platelets per hour [S.E.M.]) differed significantly from that of normal controls (12.13+/-0.2, P less than 0.001). Chronic paranoid schizophrenics (4.81+/-0.46) differed significantly from chronic nonparanoid schizophrenics (8.6+/-0.75, P less than 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 less than 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.