Brain and skeletal muscle monoamine oxidase activity in schizophrenia.

Abstract

Monoamine oxidase (MAO) activity has been studied in postmortem brain specimens from chronic schizophrenics and comparison groups by various laboratories. There is no evidence for decreased MAO activity in the brains of the schizophrenic patients, but many possible sources of error in postmortem studies make the conclusions of these studies less than definitive. However, since almost complete inhibition of brain MAO activity appears necessary before it has any functional significance, reduced brain MAO activity is unlikely to have any significance for the pathogenesis of psychosis. Brain and platelet MAO activities in man have been found not to be significantly correlated with each other. There is some evidence neuroleptic drugs may inhibit human brain MAO activity in vitro, but indirect evidence from spinal fluid and postmortem studies is not consistent with this. Decreased MAO activity has been found in the skeletal muscle of various types of psychotic patients compared to normal controls. This suggests decreased MAO activity in peripheral tissues may be a nonspecific marker for vulnerability to the development of psychopathology.