Focus on Alternative and Complementary Therapies
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Focus Alternat Complement Ther©2005 Pharmaceutical Press
Focus Altern Complement Ther 2002; 7: 108
We have previously presented separate dose-ranging studies of the acute effects of ginseng, ginkgo and their combination in healthy volunteers. In each trial, a different profile of cognitive benefits was observed. The purpose of the present study was to compare directly the effects of the three treatments.
The study used a placebo-controlled, double-blind, balanced crossover, Latin squares design in which 20 participants received 360 mg of ginkgo, 400 mg of ginseng, 960 mg of a ginseng–ginkgo combination or a placebo, on different days separated by a 7-day washout period. Cognitive performance was assessed using the Cognitive Drug Research (CDR) computerised test battery immediately prior to treatment and at 1 h, 2.5 h, 4 h and 6 h thereafter.
The primary outcome measures were five aspects of cognitive performance, which have previously been derived by factor analysis of CDR subtests. Ginkgo significantly improved the quality of episodic secondary memory at 1 and 6 hour post-dosing. Ginseng improved the accuracy of attention at 2.5 h, the quality of secondary memory at 4 h and 6 h, and the speed of retrieval of information at 4 h. The combination improved the quality of episodic memory at 1 h and 2.5 h and working memory at 1 and 6 h; it slowed the speed of attention at 4 h, which was the only evidence of impairment for any treatment in this study.
The improvement to secondary memory with ginkgo was consistent with previous findings, but the improvement to the speed of attention found before was not seen here. The findings for both ginseng and the combination are directly comparable with those previously presented.
