Ethanol-induced changes in body sway in men at high alcoholism risk.

This study measures the amount of body sway or static ataxia in 34 drinking but nonalcoholic men 21 to 25 years of age who have an alcoholic first-degree relative (the family-history-positive, or FHP, group). Results are compared with 34 control subjects matched pairwise on demographic characteristics and drinking histories, but who have no known alcoholic close relatives (the family-history-negative, or FHN, group). Each man was tested on three occasions where he drank either placebo, or 0.75 mL/kg or 1.1 mL/kg of ethanol; the subjects were repeatedly tested during the subsequent four hours. At the baseline of each of the three test sessions, the level of body sway for the two family-history groups was virtually identical. However, following the 0.75-mL/kg dose, the increase in body sway was significantly less for the FHP than for FHN group, with similar but less dramatic group differences noted following the ingestion of 1.1 mL/kg of ethanol. These results are consistent with the significantly less intense subjective feelings of intoxication after drinking for the FHP men, and also parallel findings of less intense ethanol-related changes in biologic and cognitive test scores. A decreased intensity of reaction to ethanol should be explored further as a possible genetic trait marker of a predisposition toward alcoholism.