Laboratory behavioral assessment: the effect of acute alcohol and energy drink co-ingestion on impulsivity

Consumption of alcohol may impair decision-making by increasing behavioural impulsivity, leading to increased engagement in risk behaviours. Structural analyses have generally yielded three processes thought to contribute to behavioural impulsivity: impulsive inattention, impulsive disinhibition, and impulsive decision-making. While comparison of individuals who consume alcohol mixed with energy drinks (AmED) versus alcohol alone generally indicate greater trait impulsivity for the former, there has been limited research assessing the acute effect of AmED versus alcohol on behavioural impulsivity, despite concerns that AmED consumption results in increased engagement in risky and impulsive behaviour. Consequently, the aim of the present study was to determine the effect of an acute alcohol and energy drink (ED) dose on objective measures of impulsive inattention (Immediate/Delayed Memory Task; IMT/DMT), impulsive disinhibition (Cued Go/No-Go), and impulsive decision-making (Experiential Discounting Task; EDT). Using a placebo-controlled, single-blind, crossover design, participants (N = 28) attended four sessions in which they were administered in counterbalanced order: 0.5 g/kg alcohol, 3.57 ml/kg ED, AmED, and a placebo beverage. No significant interactive AmED effects were evident for the IMT/DMT; impulsive inattention tended to increase following active alcohol consumption (with active or placebo ED) and decrease following active ED consumption (with active or placebo alcohol). There were no significant treatment effects for the measure of impulsive disinhibition, the Cued Go/No-Go Task. Greater delay discounting was evident on the EDT following active relative to placebo alcohol consumption; there was no significant interactive effect of alcohol and ED on this measure of impulsive decision-making. Overall, these results suggest limited interactive effects of alcohol and ED on the selected measures of behavioural impulsivity. However, it should be noted that general alcohol-induced impairment was not evident on some measures, and as such the dose may not have been sufficient to induce changes in performance for the treatment conditions. Further research assessing the dose-dependent effects of AmED could clarify whether an interactive effect becomes apparent with greater intake.