Background: It has been argued that consuming alcohol mixed with energy drinks (AmED) causes a subjective underestimation of intoxication and an increased level of risk-taking behavior. To date, however, there is mixed support for AmED-induced reductions in perceived intoxication, and no objective assessment of risk-taking following AmED consumption. Consequently, the present study aimed to determine the effect of alcohol and energy drink (ED) consumption on subjective measures of intoxication and objective measures of risk-taking.

Methods: Using a placebo-controlled, single-blind, cross-over design, participants (n = 28) attended 4 sessions in which they were administered, in counterbalanced order: 0.5 g/kg alcohol, 3.57 ml/kg ED, AmED, and a placebo beverage. Participants completed the Biphasic Alcohol Effects Scale and a Subjective Effects Scale at baseline and 30 and 125 minutes postbeverage administration; risk-taking was measured using the Balloon Analogue Risk Task (BART).

Results: Participants reported greater subjective intoxication, impairment, and sedation after active relative to placebo alcohol consumption, with no interactive AmED effects. However, a significant moderate magnitude increase in stimulation ratings was observed in the AmED relative to alcohol, ED, and placebo conditions. There was no independent effect of alcohol, or interactive effect with ED, on the BART. A significant, yet small magnitude, increase in risk-taking was evident in active relative to placebo ED conditions.

Conclusions: The interactive effect of AmED appears restricted to perceived stimulation, with alcohol- induced increases in subjective intoxication occurring regardless of presence or absence of ED. Engagement in risk-taking behavior was only increased by ED consumption; however, this effect was only of small magnitude; at these doses, alcohol consumption, with or without EDs, did not affect risk-taking. Further research assessing the dose-dependent effects of AmED on objectively measured risk-taking behavior could clarify whether the ED effect increases with higher doses and whether an interactive effect is observed with higher alcohol doses.