In a double-blind, placebo-controlled balanced crossover trial, 30 healthy adults were subjected to mental and cognitive tasks followed by a “mental fatigue” scaling score. When subjects were given a single dose of 200 mg of Panax ginseng there were significant improvements in mathematic tasks and significantly reduced mental fatigue scores after mental activities.
Reay JL, Kennedy DO, Scholey AB. Single doses of Panax ginseng (G115) reduce blood glucose levels and improve cognitive performance during sustained mental activity. J Psychopharmacol. 2005 19(4): 357-65