Acute alcohol administration and placebo effectiveness in older moderate drinkers: Influences on cognitive performance

Objective Placebo effectiveness and subsequent influence on cognitive performance were investigated in older moderate drinkers (ages 50-69; N = 30; 15 men) following acute alcohol administration. Method: Double-blind, placebo-controlled alcohol administration techniques were designed to produce peak breath alcohol concentration levels consistent with an episode of social drinking (∼40 mg/100 ml). Cognitive performance, measured via a covert attentional processing task, was assessed. Participants were also asked to rate their perceived levels of intoxication and impairment. Results: The placebo beverage was effective in older moderate drinkers, with 63% of participants who received placebo reporting that they received alcohol. Placebo beverage effectiveness influenced cognitive performance. Participants who received placebo, but reported they received alcohol, demonstrated slower reaction times on the covert attentional processing task, similar to those receiving alcohol. Placebo effects did not influence accuracy on the covert attentional processing task or self-reported measures of intoxication and impairment. As expected, participants who received alcohol had less accuracy on the covert attentional processing task and more self-reported impairment and intoxication than those who received placebo, regardless of placebo effectiveness. Conclusions: These results suggest that belief of having received a moderate dose of alcohol has an effect on reaction time similar to that of its pharmacological effect in older moderate drinkers. Although placebo effects are not novel, these findings suggest that cognitive processes are differentially affected. The study of moderate doses and more complex real-world tasks is an important next step.