The antagonistic placebo response to alcohol cues.

The classical conditioning model of drug tolerance makes a strong prediction of an antagonistic placebo response, or a placebo response that is opposite in direction to the effect of alcohol. In an initial experiment, 85 normal social drinkers consumed near beer (0% alcohol) while autonomic measures were recorded continuously. Subjects who reported mild intoxication (n = 11) showed a significant decrease in heart rate from predrinking baseline compared to subjects who did not report intoxication (n = 57). In a replication study with a suitable control group, subjects who received near beer and reported mild intoxication (n = 8) showed a significant heart rate and electrodermal response opposite in direction to the autonomic effects of alcohol compared to a control group that received a soft drink (n = 10). The antagonist placebo response challenges current conceptualizations of placebo responding, and has implications for classical conditioning theories of alcoholism.