AbstractObjectivesGuarana (Paullinia cupana) from the Sapindaceae family, native to the Amazon basin, is a natural stimulant herb that can be found in popular energy drinks, pharmaceutical shops or local herb shops. With the use of natural health products increasing, guarana has gained a fair amount of popularity in the past years. In this systematic review, we examined the effects of guarana supplementation on cognitive performance. A secondary objective was to compare guarana with caffeine on cognitive performance.MethodsSearches were made in PubMed using the terms ‘Guarana’ or ‘Paullinia cupana’. Filters focused on Controlled Clinical trials. Inclusion criteria were met by studies using interventions with guarana, while focusing on guarana’s effects on cognition. Participants needed to be young, healthy adults. Studies not published in English or Greek were excluded. The last date of our search was March 7, 2019.ResultsA total of 29 studies were identified and screened. After screening, 17 studies were excluded. The remaining 12 studies were found eligible for data extraction. After reading the full text of the 12 studies, 3 studies were excluded. In the end, 9 studies were found eligible for our systematic review (n = 369 participants). In these studies, guarana showed to improve reaction time and accuracy of performance at cognitive tasks. No significant differences were found when comparing guarana with caffeine.ConclusionGuarana seems to improve reaction time and accuracy of performance at tasks, but no significant effects were found when compared with caffeine. High quality randomized controlled clinical trials with a low risk of bias are needed to further study the herb.
Effects of Noninvasive Cervical Vagal Nerve Stimulation on Cognitive Performance But Not Brain Activation in Healthy Adults
