Caffeine and alcohol co-consumption linked to negative outcomes among adolescents

Heavy joint consumption of highly caffeinated energy drinks and alcohol has become more common among adolescents/young adults, and has been associated with an increase of hazardous behaviors. However, virtually no research has explored caffeine and alcohol co-consumption or its long-term consequences in adolescent animals. This animal study seeks to understand the neurobehavioral consequences of this form of binge drinking, extending a previously established mouse model of voluntary binge caffeine and alcohol co-consumption to explore adolescent consumption and responses into adulthood.

Researchers provided adolescent and adult male C57BL/6J mice with daily limited access to caffeine (0.03% w/v), alcohol (ethanol; 20% v/v), a combined alcohol/caffeine solution, or water for 14 days using a binge-like drinking paradigm called Drinking-in-the-Dark (DID). This concentration of caffeine (0.03% w/v) is similar to that found in common energy drinks such as Red Bull. Home cage locomotor activity was measured during DID in a subset of mice. Following DID, all mice rested for 18 days so that adolescents reached adulthood, whereupon all mice underwent seven days of continuous access two-bottle choice drinking for 10% (v/v) alcohol or water.

Results show that co-consumption with caffeine significantly increased alcohol intake and resulting blood alcohol concentrations (BACs) in both adolescent and adult mice. In addition, adolescent mice exhibited a uniquely robust locomotor stimulant response to caffeinated alcohol consumption. Together with human findings, these results suggest that caffeine co-consumption with alcohol may increase binge alcohol consumption in adolescents/young adults. Furthermore, this age group may be particularly sensitive to the additive stimulant effects of caffeinated alcohol consumption, an effect that may be related to the high incidence of associated negative outcomes in this population. These observations are particularly concerning given the heightened plasticity of the adolescent brain.