Platelet monoamine oxidase activity in type 1 and type 2 alcoholism

Earlier studies have identified at least two distinct subtypes of alcoholism. Type 2 is characterised by high heritability, early onset, frequent social complications and mixed misuse. With regard to temperament, the type 2 alcoholics score high in impulsiveness and sensation-seeking behaviour. Type 1 alcoholics have a later onset, lower degree of heritability and rarely there is misuse of illegal drugs. In the present study, 37 type 1 and 62 type 2 male alcoholics were compared with 36 male controls with regard to platelet monoamine oxidase (MAO) activity, which is a stable biological marker, inversely correlated to personality traits such as impulsiveness and sensation seeking. The platelet MAO activity was found to be lower in type 2 alcoholics when compared both with healthy controls and with type 1 alcoholics. Also, the type 1 alcoholics had lower platelet MAO activity than the controls. The result confirms a previous study and validates the subclassification of alcoholism according to the type 1 and 2 concept. This should be of value for future studies concerning etiology, epidemiology, treatment and prevention of alcoholism.