The effects of long-term administration of guarana on the cognition of normal, elderly volunteers.

Paulinia cupana (guarana) is a Brazilian plant given great prestige in popular medicine, for example as being a potent stimulator of brain functions. The authors assessed the effects of the long-term administration of guarana on the cognition of normal, elderly volunteers. Forty-five volunteers were studied, with a random distribution in three experimental groups: placebo (n = 15), caffeine (n = 15), and guarana (n = 15), in a double-blind study. There were no significant cognitive alterations in these volunteers.