Concomitant caffeine increases voluntary alcohol consumption in male, but not female, adolescent C57BL/6J mice.

Background: The notion that stimulating qualities of energy drinks reduce overall depressant effects of alcohol has resulted in an increase in the popularity of combining energy drinks with alcohol among young adults and teenagers. Alcohol misuse often emerges during or shortly after vulnerable adolescent years. Even though energy drinks are frequently advertised to and enjoyed by adolescents, there are limited investigations on the neurobehavioral effects of combining caffeine with alcohol during adolescence. This study sought to examine the impact of exposing C57BL/6J adolescent mice to concurrent alcohol and caffeine.

Methods: In the current study, adolescent (n = 98, 50 males and 48 females) C57BL/6J mice were given access to two bottles using an intermittent access (IA) two-bottle choice drinking paradigm for a total of 4 weeks. The experimental bottle contained either caffeine (0.015% w/v), alcohol (10% v/v), or a combination of alcohol + caffeine at the aforementioned concentrations. Adolescent male and female mice were given free access to the substance(s) for 24 h, after which the experimental bottle was taken away for another 24 h.

Results: Male adolescent mice consumed significantly more alcohol when combined with caffeine compared to male adolescent mice that had access to alcohol alone. Further, this trend was shown only in male adolescent mice and not in female adolescent mice, as females did not show any differences in alcohol consumption regardless of whether there was caffeine in the mixture. Ten days following the final removal of alcohol and/or caffeine bottles, mice were given a secondary bottle containing alcohol (10%) for 24 h. Male mice previously exposed to alcohol + caffeine consumed a significantly higher quantity of alcohol during the 24-h challenge period.

Conclusions: These data suggest that adolescent males may be more vulnerable to consuming higher amounts of alcohol when combined with caffeinated beverages.