Physiological and psychological outcomes of alcohol and energy drink co-ingestion

Survey research involving retrospective self-report of alcohol drinking experiences has revealed greater odds of physiological and psychological side-effects related to overstimulation when ingesting alcohol mixed with energy drinks (AmED) relative to alcohol alone. However, few of these studies have assessed the quantity of alcohol and ED at which symptom onset is apparent. Furthermore, despite the potential biases inherent in retrospective reporting, there is a current paucity of research assessing the acute effects of alcohol and AmED consumption on self-reported psychological and physiological outcomes in a controlled setting. As such, the aim of the present study was to examine the acute independent and combined effects of a moderate alcohol and energy drink (ED) dose on self-reported psychological and physiological outcomes. Using a single-blind, placebo-controlled, crossover design, 28 adults completed four sessions where they were administered: (i) 0.50 g/kg alcohol, (ii) 3.57 mL/kg ED, (iii) 0.50 g/kg alcohol and 3.57 mL/kg ED, and (iv) placebo. The Profile of Mood States (POMS) and a Somatic Symptom Scale were completed at baseline and 30 and 125 minutes after beverage administration. Interactive AmED effects on psychological outcomes were evident only for POMS Depression-Dejection ratings, with greater disturbance reported in the alcohol relative to AmED condition. Interactive AmED effects on physiological outcomes generally only trended towards significance, with decreased muscular tension observed only when the two constituents were consumed independently. ED consumption decreased tremors ratings when ingested without placebo alcohol. However, ED ingested independently or combined with alcohol tended to increase heart palpitation ratings. Overall, the results suggest limited evidence of interactive alcohol and ED effects, with the majority of treatment effects attributed to independent administration of alcohol or EDs. However, further research utilising higher doses is required to increase ecological validity, inform policy development, and heighten consumer awareness.