Alcohol placebos: You can only fool some of the people all of the time

Abstract

Some data from three studies of the acute psychological effects of alcohol are presented. After blind administration subjects could often tell that they had consumed alcohol, presumably because of its physiological effects. About 50% of subjects who received placebo alcohol felt slightly drunk and guessed that they had received alcohol. But, subjects who had actually received alcohol rated themselves as more drunk and were much more likely to guess that they had received alcohol. Subjects could also approximately estimate how much alcohol they had drunk. These findings suggest that the effects of unblinding should be considered when alcohol is administered in placebo designs. True blind placebo administration may only be possible when achieved BAL is < 40 mg/100 ml.