STIMULATION OF ARITHMETIC SKILLS AND HEMODYNAMIC EFFECTS BY COFFEE-DRINKING : DOUBLE-BLIND ANALYSIS WITH DIFFERENT CONCENTRATIONS OF CAFFEINE

Abstract

Effects of caffeine on arithmetic performance were investigated with 217 university students. A double-blind study for arithmetic skill test and hemodynamic effects was carried out after drinking caffeine-free or caffeine-containing (100, 180 and 250 mg) coffee. Eleven rounds of the arithmetic tests were performed ; first four rounds before, and subsequently seven rounds after coffee break. Each round consisted of three 1-min arithmetic tests. The arithmetic skill for each round was averaged. Simultaneously, heart rate and blood pressure once a round were also measured. The mean value of arithmetic skill at the 4th round (n=217) was 87.3±1.8/min. The heart rate and mean blood pressure were 72.7±1.7 beats/min and 101.7±4.1 mmHg. As compared with caffeine-free group, caffeine at 100 mg significantly enhanced arithmetic skill for 60 to 90 min after coffee-drinking. The mean blood pressure was increased for 30 to 60 min after coffee-drinking (with caffeine 180 mg). But the ratio of arithmetic errors and heart rate were unaffected. At 250 mg, caffeine rather depressed arithmetic skill and blood pressure. These results indicate that caffeine (100 to 180 mg)-containing coffee drinking can enhance arithmetic skill and modulate hemodynamic actions, presumably resulting from stimulation of the central nervous system and cardiovascular system.