Platelet MAO activity as a biological marker in subgroups of alcoholism.

In the Stockholm Adoption Study, two types of alcoholism, "Type I" and "Type II", have been identified on the basis of genetic predisposition. In the present study, this classification has been applied to a clinical sample. The two types of alcoholism were clinically clearly identifiable. Type I alcoholism was characterized by late onset and few social complications. Type II alcoholism was characterized by early onset, use and abuse not only of alcohol, but also of glue, cannabis, amphetamine and opioids, together with several social complications. The subjects with Type II alcoholism had also more alcoholism and depression among their first-degree relatives than the subjects with Type I alcoholism. Furthermore, the two types of alcoholism were separable by means of the biological marker - platelet MAO activity. While platelet MAO activity was normal in Type I alcoholics, as compared with healthy controls, it was clearly low in the Type II alcoholics. This subclassification of alcoholism seems to be of value in future studies concerning the etiology, epidemiology and treatment of alcoholism.