Poster Presenter

Effects of Caffeine on Changes in Cerebral Blood Volume and Oxygenation and in Cognitive-Task Performance: From a View Point of Individual Difference Based on Sensitivity to Caffeine
Tadashi NIIOKA, Daiki YOSHIDA
Japan

The present study was carried out to investigate effects of caffeine on blood volume and oxygenation in the prefrontal association cortex and cognitive-task performance, focusing on individual differences. Relative changes in the blood volume and oxygenation were measured noninvasively using continuous-wave near-infrared spectroscopy. A modified Stroop color-word task we developed was used as a cognitive test. Five caffeine-sensitive subjects (out of a total of 10 volunteers) showed deterioration in performance compared with placebo after an intake of 200 mg caffeine with an accompanying decrease in concentration of oxygenated hemoglobin in the prefrontal region. Thus it is indicated that caffeine consumption by a caffeine-sensitive individual decreases not only the cerebral oxygenated hemoglobin concentration during the modified Stroop task but also the performance in the cognitive task. These results combined with the results of another experiment, a high inspired oxygen concentration experiment, suggest that the deterioration of the performance after caffeine administration in the caffeine-sensitive individuals would be due to insufficient oxygen supply by caffeine in the prefrontal region.