This study investigated the effects of acute doses of Ginkgo biloba extract (GBE) on memory and psychomotor performance in a randomized, double-blind and placebo controlled 5-way cross-over design. Thirty-one volunteers aged 30-59 years received GBE 150 mg (50 mg t. d.s), GBE 300 mg (100 mg t.d.s.), GBE 120 mg mane and GBE 240 mg mane and placebo for 2 days. Following baseline measures, the medication was administered at 0900 h for the single doses and at 0900, 1500 and 2100 h for the multiple doses. The psychometric test battery was administered pre-dose (0830 h) and then at frequent intervals until 11 h post dose. The results confirm that the effects of GBE extract on aspects of cognition in asymptomatic volunteers are more pronounced for memory, particularly working memory. They also show that these effects may be dose dependent though not in a linear dose related manner, and that GBE 120 mg produces the most evident effects of the doses examined. Additionally, the results suggest that the cognitive enhancing effects of GBE are more likely to be apparent in individuals aged 50-59 years.
Copyright 1999 John Wiley & Sons, Ltd.