A low- dose of caffeine suppresses EEG alpha power and improves working memory in healthy University males

The effects of a low dose of caffeine, administered in the morning, on brain wave activity and cognitive function were investigated in 25 healthy university Southeast Asian men (mean age ±standard deviation: 21 ± 2 years). Participants received a placebo (PLA) or a 50 mg caffeinated drink (CAF) under randomized, double-blind crossover conditions, with 1 week between conditions. Brain wave activity was assessed using electroencephalography (EEG) from a 5 min eyes-closed resting state. Cognitive function, i.e., visuomotor processing speed, working memory, and attention were assessed using the trail-making test A (Trails A) and B (Trails B), and digit span Forwards (DF), respectively. All tests were examined before drinking (BD), 30 min after drinking (AD), and 35 min after 5-min isokinetic exercise (AE). [Results] The CAF showed a significant decrease in the percentage changes from baseline (%∆) of alpha wave activity over the midline electrodes, i.e., frontal, central, and occipital areas after AD (p<0.05). Data from cognitive function tests were significantly improved after AD (p<0.05). A significant inverse correlation between the diminished alpha wave activity over the midline central and occipital cortical regions and the Trails B positive scores were observed (p<0.05). [Conclusion] The diminishment in resting alpha wave activity and improvement of cognitive function on working memory assessed by the Trails B following caffeine consumption would support the stimulant effects of low-dose caffeine as a morning wake-up drink in young adults.