Effects of caffeine and alcohol on mood and performance changes following consumption of lager

Rationale: The present study examined whether caffeine would modify the behavioural effects of alcohol. Objectives: The aim of the study was to determine whether caffeine modifies the effects of alcohol on mood and psychomotor performance and to identify possible dose–response and temporal relationships. Methods: A double-blind study examined the effects of three successive lager drinks (330 ml each) in the early afternoon on mood and psychomotor performance assessed at 30-min intervals over a 2-h period. Participants carried out a baseline session and were then randomly assigned to one of six conditions formed by combining three different doses of caffeine (0, 62.5 and 125 mg per drink) with either no alcohol or 4.3 % alcohol. One hundred and forty-six young adults (65 male, 81 female; age range 18–30 years) participated in the study. Mood (alertness, hedonic tone and anxiety) was assessed before and after performing simple reaction time and choice reaction time tasks. Results: Alcohol was associated with higher hedonic tone (p < 0.005), reduced anxiety (p < 0.05) and reduced alertness (p < 0.005). Caffeine had no modifying effect on hedonic tone or anxiety. However, the highest dose of caffeine did remove the effect of alcohol on alertness (p < 0.05). Effects of alcohol and caffeine were found on the performance tasks (all p values < 0.05) but these were independent effects. Conclusions: The results from the present study confirm that caffeine does not remove the negative effects of alcohol on performance although high doses counteract the drop in subjective alertness produced by alcohol