Phytother Res 1999 (Aug 13); (5): 408–15
HPRU Medical Research Centre,
University of Surrey,
Guildford GU2 5XP, UK
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.