The Effects of Alcohol, Caffeine and Expectancies on Personal Agency, Impulsivity and Risk Taking

Concurrent use of caffeine and alcohol is a rapidly growing phenomenon among young adults. Survey research indicates that caffeinated alcohol use is associated with a variety of health-risk behaviors although the mechanisms by which the combination may confer increased risk over alcohol alone are not well understood. Burgeoning research from the laboratory demonstrates that although caffeine only mildly antagonizes the effects of alcohol, individuals nonetheless feel less impaired, and therefore may be more likely to drive and to continue to drink alcohol. These findings may be explained by both the pharmacological effects of caffeine and by individuals’ expectations for caffeine to counteract the untoward effects of alcohol. The current study examined whether select affective, cognitive and behavioral outcomes, hypothesized to contribute to risk behavior, were modified by caffeinated alcohol or the expectation of receiving caffeinated alcohol. A 2 (caffeine instruction: told yes, told no) by 2 (caffeine consumption: consumed, did not consume) mixed design was employed and 146 male and female social drinkers between the ages of 21 and 30 were randomly assigned to receive either: 1) alcohol, 2) alcohol and caffeine, 3) alcohol and placebo caffeine, 4) alcohol + told no caffeine, get caffeine. Results suggest that the consumption of caffeinated alcohol may elevate risk for continued drinking, reduce sensitivity to intoxication and decrease reaction time without affecting accuracy. Conversely, consumption as well as the expectation of consuming caffeinated alcohol may reduce inattention, protect against some aspects of alcohol-related performance decrements and better preserve judgments of performance and agency. Together these findings indicate that caffeine, when combined with alcohol, has both beneficial and detrimental effects on mechanisms thought to contribute to risky behavior.