Frequent intake of cakes attenuates the effect of energy drinks on activity of medial prefrontal cortex during calculation task

Abstract

Several caffeine-containing beverages, that is, energy drinks, are sold worldwide and many young adults frequently drink them, who believe that energy drinks give them increased energy and improve their performance in tasks. However, their effect on brain activity is controversial. In this study, we aim to clarify the effect of energy drinks on brain function, especially the activity of the medial prefrontal cortex (MPFC) and dorsolateral prefrontal cortex (DLPFC), by functional near-infrared spectroscopy (fNIRS) during calculation tasks. We found that the number of errors was not decreased and the concentration of cortisol in saliva was not improved by energy drink intake during calculation tasks. However, the calculation time was shortened by energy drink intake. We also found that activities of MPFC and DLPFC varied among the participants; they increased in one and decreased in others. We found that the participants with an increased MPFC activity following energy drink intake frequently drank milk and less frequently ate cakes. We concluded that the effect of energy drinks on MPFC activity during calculation tasks is limited and it varies depending on the frequency of food (milk and cakes) intake.