Plasma GABA-like activity in response to ethanol challenge in men at high risk for alcoholism

Sons of alcoholic fathers (high risk, HR) and matched control men from families without alcoholism (low risk, LR) were administered, in a randomized double-blind fashion, either a placebo beverage or an isovolemic beverage containing ethanol (0.8 g/kg). Serial blood sampling for determination of plasma gamma-aminobutyric acid (GABA)-like activity, mood, and intoxication ratings were performed. The HR subjects were found to have significantly less plasma GABA-like activity than LR during the placebo condition. The alcoholic beverage condition washed out the differences in plasma GABA between groups. Significant interactions between risk group status and beverage conditions were found with respect to plasma GABA-like activity. Alcohol produced an increase in mean GABA-like activities among HR subjects, whereas a slight decline was noted among LR subjects. Plasma GABA-like activity also had a significant inverse correlation with self-reports of perceived tension in the placebo condition, and tension, confusion, and intoxication in response to the alcoholic drink. Since previous investigators have reported reduced plasma GABA levels in alcoholic individuals, reduced plasma GABA-like activity may be a biological marker for vulnerability to alcoholism or for heightened tension as a behavioral factor that predisposes to alcoholism.