Low platelet monoamine oxidase activity in human alcoholics.

Platelet monoamine oxidase (MAO) activity was found to be significantly reduced in human alcoholics as compared to matched controls. A probable transitory increase in activity was observed during the abstinence phase. The low platelet MAO activity was not due to iron deficiency or to the presence of acetaldehyde. Since we have previously found a lowered MAO activity in the brains of suicide victims, especially in those with a previous history of alcohol abuse, we suggest that low platelet MAO activity reflects a primarily "weak" monoaminergic system in the CNS which causes an increased vulnerability to alcohol abuse and suicidal behaviour.