Effects of Acute Alcohol on Sex-Specific Delay Discounting and Subsequent Sexual Decision Making Among MSM

For decades, men who have sex with men (MSM) have carried the heaviest burden associated with the HIV epidemic in the United States. Although MSM represent a minority (i.e., approximately 4%) of the male population in the United States, in 2010 MSM accounted for 78% of new HIV infections among males. Furthermore, the estimated number of new HIV infections attributed to male-to-male sexual contact is currently rising. In order to improve interventions to decrease transmission of HIV among MSM, it is important to have a better understanding of predictors of risky sexual behavior. Alcohol use is among the most reliable predictors of risky sexual behavior. Unfortunately, studies of alcohol use and risky sex among MSM have mainly relied on survey-based methods that cannot advance our understanding of the causal mechanisms linking acute alcohol use to HIV risk behavior.

This study will utilize an "alcohol/placebo/nonalcohol" design to examine the mechanisms underlying the association between the acute effects of alcohol (i.e., pharmacological and expectancy) and risky sexual decision making in MSM. Focal mechanisms include sex-specific delay discounting (SSDD), and the core constructs of the Cognitive Mediation Model. The alcohol/placebo/nonalcohol design involves three conditions. In the alcohol condition (target BrAC = 0.080g%), the participant will be told he is receiving alcohol and will receive beverages of 1:4 parts vodka and tonic water with dashes of lime juice and mint, all mixed in his presence. In the placebo condition (target BrAC = 0.000g%), the participant will be told he is receiving alcohol but will receive beverages of 1:4 parts flat tonic water (served from a vodka bottle) and tonic water, with a minimal amount of vodka "floated" on the surface (using a lime juice bottle) to provide the smell and taste of vodka, with lime juice and mint, all mixed in his presence and served in glasses with vodka-soaked rims. In the true control (or nonalcohol) condition, the participant will be told he is receiving no alcohol and will be given water (poured in his presence) in a volume comparable to the other conditions. This 3-group design will enable us to test the pharmacological effects of alcohol while accounting for potential expectancy effects. Participants (Target N = 150-180) will be randomly assigned to one condition; all will undergo the same protocol, which will be completed within one experimental session. The study protocol consists of baseline assessment, followed by beverage administration, followed by post-drinking assessment of SSDD and sexual decision making, followed by debriefing.