Brain and skeletal muscle monoamine oxidase activity in schizophrenia
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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.
Insights
Studies on chronic schizophrenics show no definitive evidence of reduced brain monoamine oxidase (MAO) activity, suggesting it
Area of Science:
- Neuroscience
- Psychiatry
- Biochemistry
Background:
- Monoamine oxidase (MAO) activity in postmortem brain specimens of chronic schizophrenics has been investigated.
- Previous studies on MAO activity in schizophrenia brains yielded inconclusive results due to potential errors in postmortem analysis.
Purpose of the Study:
- To evaluate the role of monoamine oxidase (MAO) activity in the pathogenesis of psychosis.
- To investigate the correlation between brain and platelet MAO activities.
- To explore the potential inhibitory effects of neuroleptic drugs on human brain MAO activity.
Main Methods:
- Analysis of postmortem brain specimens from chronic schizophrenics and comparison groups.
- Comparison of MAO activity in brain and platelet samples.
- Review of indirect evidence from spinal fluid and postmortem studies regarding neuroleptic drug effects.
Main Results:
- No consistent evidence for decreased MAO activity in the brains of schizophrenic patients was found.
- Significant correlation between brain and platelet MAO activities in humans was absent.
- Decreased MAO activity was observed in the skeletal muscle of psychotic patients compared to controls.
Conclusions:
- Reduced brain MAO activity is unlikely to be significant in the pathogenesis of psychosis, as substantial inhibition is required for functional impact.
- Peripheral MAO activity in skeletal muscle may serve as a nonspecific marker for psychopathology vulnerability.
- Further research is needed to clarify the role of MAO in psychiatric disorders.