Effects of American ginseng (Panax quinquefolius)on neurocognitive function: an acute, randomised,double-blind, placebo-controlled, crossover study. Andrew Scholey… & Con Stough（Psychopharmacology (2010) 212:345–356）
Results There was a significant improvement of working memory (WM) performance associated with P. quinquefolius. Corsi block performance was improved by all doses at all testing times. There were differential effects of all doses on other WM tasks which were maintained across the testing day. Choice reaction time accuracy and ‘calmness’ were significantly improved by 100 mg. There were no changes in blood glucose levels.
Conclusions This preliminary study has identified robust working memory enhancement following administration of American ginseng. These effects are distinct from those of Asian ginseng and suggest that psychopharmacological properties depend critically on ginsenoside profiles. These results have ramifications for the psychopharmacology of herbal extracts and merit further study using different dosing regimen and in populations where cognition is fragile.