Caffeinated alcoholic beverages target young adults with the promise that the caffeine will counteract the sedating effects of alcohol and thus let the consumer remain alert and active longer, while continuing to drink. It is likely that in the minds of some young people, this promise also translates into the idea that mixing caffeine with alcohol allows one to drive more safely than would be possible after having consumed an equivalent amount of non-caffeinated alcoholic beverage. These are dangerous assumptions because (1) alertness may not indicate the absence of impairment under intoxication and (2) next-day impairment from the residual effects of heavy drinking may be exacerbated by mixing caffeine and alcohol. We will compare the acute and residual effects of caffeinated and non-caffeinated beer in terms of a highly relevant outcome - the ability to drive safely.
The long-term objectives of this program of research are to investigate factors that predict or contribute to performance decrements after alcohol ingestion, with a focus on behaviors most relevant to public health, such as driving. The primary specific aims of the proposed work are:
AIM 1: To compare the acute effects of caffeinated alcohol, non-caffeinated alcohol, caffeinated placebo, and non-caffeinated placebo on driving-related impairment, as measured by performance on a driving simulator and the Psychomotor Vigilance Test (PVT), a test of sustained attention/reaction time. We hypothesize that caffeinated beverage will result in less impaired simulated driving ability and better PVT performance acutely, compared to non-caffeinated beverage, but that performance on these measures following both caffeinated and non-caffeinated beverage be impaired relative to placebo beverages.
AIM 2: To compare the residual effects of caffeinated alcohol, non-caffeinated alcohol, caffeinated placebo, and non-caffeinated placebo on next-day driving-related impairment, as measured by a driving simulator and the PVT. We hypothesize that caffeinated beverage will result in greater impairment in next-day simulated driving and attention/reaction time, relative to non-caffeinated beverage, and that performance following both caffeinated and non-caffeinated alcoholic beverages will be impaired relative to corresponding placebo beverages.
AIM 3: To compare the acute effects of caffeinated alcohol, non-caffeinated alcohol, caffeinated placebo, and non-caffeinated placebo on self-rated ability to drive, as measured by a self assessment of ability-to-drive questionnaire, and estimate of blood alcohol concentration (BAC). We hypothesize that caffeinated alcoholic beverages will result in greater confidence in ability to drive and lower estimates of BAC, compared to non-caffeinated alcoholic beverages, but that for both alcoholic beverages, confidence in driving ability will be lower and estimates of BAC will be greater, relative to placebos.
AIM 4: To compare the residual effects of caffeinated alcohol, non-caffeinated alcohol, caffeinated placebo, and non-caffeinated placebo on self-rated ability to drive. We hypothesize that caffeinated alcoholic beverage will result in lower confidence in ability to drive and higher estimates of BAC, compared to non-caffeinated alcoholic beverage, but that for both alcoholic beverages, confidence in driving ability will be lower and estimates of BAC will be greater, relative to placebo.
