Another botanical that may be helpful for cognitive support, in combination with ginkgo, is ginseng (Panax ginseng). The biologic effects of the various constituents of ginseng are complex: While one of its phytochemicals shows affinity for the nicotinic acid receptor,21 a receptor for which reduced stimulation is associated with cognitive decline, another of its phytochemicals blocks this receptor.22 However, in both animal and clinical research, a combination of ginseng with ginkgo seems to hold promise. In rats, for example, a gink-go=ginseng combination was shown to enhance the learning ability of both older and younger rats.23 A recent double-blind, placebo-controlled trial of more than 250 human subjects over a 14-week period has been reported. In this study, subjects' cognition=memory were assessed every 4 weeks using a number of standard scales and questionnaires. Overall, there was significant improvement (mean 7.5%) in subjects who received the botanical combination (120 mg per day of ginkgo and 200 mg per day of ginseng), including gains in working and long-term memory.24 A double-blind, placebo-controlled, balanced-crossover study with 27 healthy young adults examined the effects of ginseng with cognitive-demanding tests. The results showed that Panax ginseng supplementation enhanced performance of a mental arithmetic task and ameliorated the increase in subjective feelings of mental fatigue experienced by the participants during the later stages of the sustained, mentally demanding tasks.25 In a similar placebo-controlled, double-blind, balanced, crossover design study, 20 healthy young adults received 200, 400, or 600 mg of Panax ginseng, with a seven-day wash-out period between treatments. The results showed a significant improvement in "Quality of Memory'' and the associated "Secondary Memory'' factor at 1, 2.5, 4, and 6 hours after the day's treatment following 400 mg of ginseng.26
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