The effect of caffeine on blood pressure and cognitive function in a Stroop Task and single reaction test in healthy and moderately active University students.

Background: Previous research has been conducted to evaluate the effect of caffeine on cognitive function, reaction time, and blood pressure (BP) in different population groups. To date, no study has evaluated the effect of caffeine in healthy individuals who are moderately active in non-specific sport. Objective: To investigate the acute effect of caffeine in the form of 3mg/kg, on cognitive function, reaction time (RT), and BP in moderate active healthy individuals. Design: In a placebo-controlled, single blinded design, twenty normotensive (7 males and 13 females) University students took part in the study. Following a 12-hr caffeine abstinence, participants were asked to consume caffeinated coffee in the form of 3mg/body weight espresso shots or decaffeinated coffee, on two occasions divided by a week wash out period. Cognitive function using the card version of the Stroop Task, RT using a simple online RT test, BP, and HR were all assed preoperatively and postoperatively. Results: Caffeine in the decaffeinated coffee was significantly lower compared to the caffeinated coffee (41.8±7.8 vs 33mg±5.6 P=0.031). Mean SBP and DBP increased significantly from 102±12.2mmHg to 106±13.1mmHg and from 72±6.9mmHg to 75±8.2mmHg respectively post caffeine consumption. No effect was seen in BP, when subjects ingested decaffeinated coffee. HR was significantly decreased with caffeinated coffee from 78±9.9 bpm to 73±10.1 bpm. Upon decaffeinated consumption, HR was decreased, but no significantly. Significant effects on performance with respect to time was seen after caffeinated consumption in all tests apart from test 1, while no improvements were seen in errors made. No improvement was observed in RT in either conditions. Conclusion: Higher doses of caffeine has the potential to increase BP within the normal ranges, and improve RT needed to respond on the Stroop tasks, but not on a single RT test in comparison to lower caffeine levels. Keywords: caffeine, cognitive function, reaction time, blood pressure.msc_dietunpub2167_ethesesunpu