Short term impact of single dose of caffeine on reaction times, cognitive processing and cardiovascular parameters in a healthy adult population

Background: Caffeine is an ergogenic aid and has a stimulating effect on human body. About 85% of adults around the world consume caffeine regularly in the form of tea, coffee, cocoa products, cola beverages and energy drinks. Energy drinks are very common in athletes and young adults as they improve cognition, reaction times, and muscle contraction and enhance performance and memory. However, most of the studies conducted using energy drinks have focussed on athletes but this study is going to investigate the effect of caffeine in the form of energy drink on a healthy adult population to investigate its effect. Aims & objectives: This study will investigate the short-term effect caffeine has on cognition and reaction times with a single dose of caffeine in a healthy adult population. The study will also investigate the effect it has on cardiovascular parameters. Methods: The study was performed in the mornings after 10-12 hours of overnight abstinence from caffeine on a healthy adult population from QMU. Baseline tests were measured (height, weight, blood pressure, heart rate, Stroop test, reaction times). Participants were given 250ml of sugar-free Red Bull (group 1) or 250ml of caffeine-free diet coke (group 2). After rest for 45 minutes, their tests were repeated (BP, HR, reaction time and Stroop test). The procedure was repeated after a week with the alternative drink (to prevent an order effect) on both groups. Results: Sugar-free Red Bull energy drink significantly reduced time to complete Stroop test from 40.15±8.55 to 33.88±7.32 (p=0.01) and reaction times 0.36±0.07 to 0.31±0.04 (p=0.02) when compared to caffeine-free diet coke. There were some changes in cardiovascular parameters as heart rate reduced significantly from 68.8±8.92 to 61.5± 6.43 (p=0.005) but there were no statistically significant change in blood pressure as SBP only increased to 115.1±14.45 from 111.6±10.25 (p=0.1) and DBP to 76±14.45 from 73.7±12.68 (p=0.2). Conclusion: These findings suggest that caffeine can enhance cognitive performance and reaction times even at lower and single dose (80mg). Evidence considered in this research study suggests that moderate caffeine intake is not associated with increased risk of CVD in general population, and decreased heart rate after caffeine consumption has a plausible pharmacological explanation