Differentiating the Contribution of Pharmacological from Alcohol Expectancy Effects to Changes in Subjective Response and Priming Over Successive Drinks

Background Alcohol consumption can prime motivation to continue drinking and may contribute to excessive drinking. Most alcohol administration research assesses the effect of a single alcohol dose on outcome measures; however, this differs from typical drinking occasions in which several drinks are consumed over time. This research tracks priming measures (alcohol urge, latency to first sip, and consumption time) and subjective effects (intoxication, stimulation, and sedation) across consumption of 5 drinks, over a period of 2.5hours. Alcohol, placebo, and no-alcohol (i.e., soft drink) conditions are compared with isolate the effects of alcohol expectancies and differentiate these from alcohol's pharmacological effects. Methods Alcohol urge and subjective state were measured before and after an initial drink was consumed (preload: alcohol, placebo, or no-alcohol). Four additional drinking phases followed whereby participants had access to 2 drinks (alcohol/no-alcohol, or placebo/no-alcohol). Experimental priming (urge, latency to first sip, consumption time) and subjective effect (intoxication, stimulation, and sedation) outcomes were recorded after each drink. Results The pattern of alcohol urge following placebo drinks differed compared with alcohol and no-alcohol consumption, Fs(1, 90)>4.10, ps<0.003. There was a linear decrease in urge in the no-alcohol condition, while in the alcohol condition urge increased after the first few drinks before decreasing. Urge ratings showed the opposite pattern in the placebo condition (a decrease followed by an increase). Alcohol produced the highest ratings of lightheadedness, F(5, 440)=2.8, p<0.02, but both alcohol and placebo produced increased sedated feelings, Fs19.05, ps0.001. After placebo, urge was positively related to liking and enjoying the alcoholic drinks and feeling more stimulated (rs0.31, ps0.01). Conclusions In social drinkers, different factors may affect priming during different stages of a drinking episode. For example, the pharmacological effects of alcohol appear involved in priming during the initial stages of drinking. When alcohol expectancies are activated, blocking access to alcohol can increase urge, supporting Tiffany's cognitive processing model of craving.