The primary active ingredient in North American ginseng is a group of chemicals called ginsenosides. These ginsenosides have many pharmacological actions, including various actions on the central nervous system.
Two clinical trials, with 101 participants, showed that the ginseng extract enhances memory in both normal, young (20 to 24 years of age) and older adults (46 to 64 years of age). The second trial demonstrated that the product enhanced visual working memory and other neurological measures in 64 patients with schizophrenia. Laboratory studies have also demonstrated improved learning and memory, nerve cell protection, and promotion of nerve cell growth.
Other laboratory and animal studies suggest that North American ginseng may exert a wide range of activity on the central nervous system, including the treatment of Attention Deficit Hyperactivity Disorder (ADHD) , an anticonvulsant effect, a pain relieving effect and protection of nerve cells from damage caused by a lack of oxygen (suggesting it might help prevent or limit impairment from strokes). These are very early results and require more research before these effects can be safely tested and confirmed in humans.
Sloley BD, Pang PK, Huang BH et al. North American ginseng extract reduces scopolamine-induced amnesia in a spatial learning task. J Psychiatry Neurosci 1999;24(5):442-52.
Rudakawich M, Ba F, Benishin CG. Neurotrophic and neuroprotective actions of ginsenosides Rb(1) and Rg(1) Planta Med 2001;67(6):533-7
Lyon MR, Cline JC, Totosy de Zepetnak J, Shan JJ, Pang P, Benishin C. Effect of the herbal extract combination Panax Quinquefolium and ginkgo biloba on attention-deficit hyperactivity disorder: a pilot study. J Psychiatry Neurosci 2001;26(3);221-8