Increased ethanol choice in social drinkers following ethanol preload

This study showed that normal social drinkers were more likely to consume ethanol after receiving a "priming" (preload) dose of ethanol. Twenty-eight non-problem drinkers (average consumption 9 drinks/week) participated in a six-session, double-blind choice procedure. On the first two sessions they sampled beverages containing ethanol (0.8g/kg) or placebo (mix alone), between which they would choose on subsequent choice sessions. On the third session ("dummy" choice session) subjects were first asked to indicate verbally which beverage they preferred. If they chose the ethanol-containing beverage the experimenter negotiated with each subject to determine the minimum amount of money (from $1 to $30) needed to switch his or her choice from ethanol to placebo. Once this amount was determined it remained fixed for the subsequent three preload/choice sessions. Thus, on choice sessions subjects chose between the beverage which contained ethanol, and placebo plus the amount of money established in Session 3. On the preload/choice test sessions (Sessions 4-6) subjects received preloads of ethanol (0, 0.25 or 0.5g/kg) 1h before being given the choice between the sampled ethanol beverage and the placebo beverage plus money. The frequency of ethanol choice was the primary dependent variable. Subjective drug effects, including ratings of desire for the sampled substances, were also measured. Twenty subjects initially chose ethanol on Session 3 and switched their choice with a monetary incentive. Of these 20 subjects, four chose ethanol after the placebo preload, seven chose ethanol after the low-dose ethanol preload, and 11 chose ethanol after the higher ethanol preload (significant linear trend, Mantel-Haenszel test, p < 0.03). Ratings of desire for the ethanol-containing beverage increased after the higher preload. These results suggest that ingestion of a moderate dose of ethanol increases the tendency to continue drinking, even among normal social drinkers.