Psychopharmacol Bull. 2002 Summer; 36(3): 108-23.

Ginkgo biloba: a smart drug? A systematic review of controlled trials of the cognitive effects of ginkgo biloba extracts in healthy people.

Canter PH, Ernst E.

Department of Complementary Medicine, University of Exeter, United Kingdom. P.Canter@ex.ac.uk

Extracts of Ginkgo biloba are widely used to alleviate or delay the progress of age-related cognitive impairment. Its use as a "smart" drug by healthy individuals has also been commercially promoted. The aim of this study was to systematically review and critically evaluate the trial data to test whether Ginkgo biloba enhances cognitive function in healthy subjects. Literatures searches of 6 computerised databases were made for placebo-controlled, double-blind trials of the effect of standardized Ginkgo biloba extracts on cognitive function in healthy subjects. Trials published in any language were included and data were extracted independently by the authors following a standardized protocol. Nine trials were identified, and these were mainly short term. The longest had a treatment period of 30 days. Trials were mostly of good intrinsic methodological quality, but certain aspects of methodology were inadequately reported by all trials. Taken together, these studies indicate no marked or consistent positive effects of Ginkgo biloba on any particular objective measure of cognitive function. A positive subjective effect was reported only in the longest trial. It is concluded that a positive effect of Ginkgo biloba on cognitive function is not proven by data from rigorous clinical trials. The use of Ginkgo biloba as a "smart" drug cannot be recommended on the basis of the evidence available to date, and there is a particular need for further long-term trials with healthy subjects.