Differential, dose dependent changes in cognitive performance following acute administration of a Ginkgo biloba/Panax ginseng combination to healthy young volunteers.

We have previously shown differential cognitive improvements following single doses of Ginkgo biloba and of Ginseng. There is also evidence that chronic administration of a combination of standardised extracts of Ginkgo biloba and Panax ginseng may improve aspects of cognitive performance both in pathological populations and the healthy middle aged. No investigation has thus far looked either at the cognitive effects of single doses of such a combination, nor the effects of the combination on healthy young volunteers. The present study investigated whether acute administration of a combination of standardised extracts of Ginkgo biloba (GK501, Pharmaton SA) and Ginseng (G115, Pharmaton SA) had any consistent effect on mood and aspects of cognitive performance ("quality of memory", "secondary memory", "working memory", "speed of memory", "quality of attention" and "speed of attention") that can be derived by factor analysis of the cognitive drug research computerised assessment battery. The study followed a placebo-controlled, double blind, balanced, crossover design. Twenty healthy young adult volunteers received 320, 640, and 960 mg of the combination, and a matching placebo, in an order dictated by random allocation to a Latin square, and with a seven-day wash-out period between treatments. Following a baseline cognitive assessment, further test sessions took place 1, 2.5,4 and 6 h after the day's treatment. The most striking result was a dose-dependent improvement in performance on the "quality of memory" factor for the highest dose. Further analysis revealed that this effect was differentially targeted at the secondary memory rather than the working memory component. There was also a dose dependent decrement in performance of the "speed of attention" factor for both the 320 and 640 mg doses. These results are discussed in the context of previous findings within this series of studies.