Studies of animal models have been useful in distinguishing potential markers. Alcoholic subjects had greater increases of slow alpha activity and greater decreases of fast alpha activity after alcohol intake than controls. The high risk subjects also showed greater decreases in mean alpha frequency after alcohol intake. The EEG findings suggested that subjects at high risk for alcoholism are physiologically more sensitive to alcohol than control subjects. Corsico et al.
Monoamine oxidase is an enzyme involved in the metabolism of biogenic amines.
Platelet MAO activity was normal in Type I alcoholics and in healthy controls, but was lower in Type II alcoholics, suggesting a possible biological marker for alcoholism. However, in a study by Tabakoff et al. Instead they found that monoamine oxidase activity was correlated with the time since the last drink in alcoholics, but not in controls. Linkage studies consider the cosegregation of a particular disorder with marker genes in families. Linkage analysis has been made easier with the use of restriction fragment length polymorphisms, or RFLPs.