Researchers invited 26 adult social drinkers (13 males, 13 females) to attend six double-blind sessions that involved drinking alcohol and energy drinks, alone and in combination. On each test day, participants received one of six possible doses: 1) vodka + decaffeinated soft drink, 2) vodka + medium energy drink, 3) vodka + large energy drink, 4) decaffeinated soft drink, 5) medium energy drink, and 6) large energy drink. After each session, the participants rated their desire for alcohol and their breath alcohol concentration was measured.
Results showed that alcohol alone increased the subjective “desire for more alcohol” compared to placebo doses. AmEDs increased the desire for more alcohol beyond that observed with alcohol alone. In summary, this study provides laboratory evidence that AmEDs lead to a greater desire to drink alcohol than the same amount of alcohol consumed alone, and are consistent with animal studies showing that caffeine increases the rewarding and reinforcing properties of alcohol.