Monoamine oxidase-A and -B activities in the brain stem of schizophrenics and non-schizophrenic psychotics.

In the pons of autopsy cases who had suffered from chronic schizophrenic or nonschizophrenic psychoses, an increased activity of monoamine oxidase -B but not -A was found, as compared with age-matched controls. Consequently, the ratio of the activities of MAO-B : MAO-A was elevated in the cases of psychosis. There was no significant difference in enzyme activities between schizophrenic and nonschizophrenic psychoses. Lobotomy appeared not to influence the monoamine oxidase activity. Increased ratios of the activities of MAO-B : MAO-A in various brain parts of chronic schizophrenics in comparison with age-matched controls was found in the previously published data of Eckert et al (1980) and Schwartz et al. (1974) but not Crow et al. (1979). The mechanism underlying the change in enzyme activities is unclear. There seems to exist an association between an increased monoamine oxidase-B activity and degenerative processes in the brain resulting in loss of neuronal activity. The change observed may be linked either to pathological processes associated with chronic psychosis or to long-term treatment with neuroleptic drugs.