The Chinese tree Ginkgo biloba or "maiden hair tree" is extensively cultivated for the exploitation of the medicinal properties of its leaves. From these, a well-defined extract designated "EGb 761" has been developed, which was commercialized initially as Tanakan, Tebonin and Rokin; a similar product, Kaveri (LI 3170), also exists. The major therapeutic applications for these products are "cerebral insufficiency", other cerebral disorders, neurosensory problems and peripheral circulatory disturbances.
Four primary concepts of action have been proposed to explain the pharmacotherapeutic benefits of EGb761; these are: vasoregulatory, cognition-enhancing, stress-alleviating, and gene-regulatory. These actions are believed to be realized through the principal active ingredients, flavonoids and the terpenoids ginkgolides and bilobalide acting simultaneously in concert, combination and synergy, so-called polyvalent action. It has been proposed that EGb761 may improve the memory of healthy volunteers, and in an assessment meta-analysis of forty clinical studies, it was reported that Ginkgo was able to improve the twelve different symptoms comprising 'cerebral insufficiency', all of which are manifest in the elderly.
These were supported in a second major study, using LI1370. However, in both instances, the evidence was largely based upon the results of self-assessment questionnaires. Latterly, in a large double blind study of men and women with the diagnosis of uncomplicated dementia who were administered Ginkgo for a year, a further positive outcome was claimed.
In this study, patients were tested using ADAS-cog, GERRI and CGIC. It is suggested that whilst these different outcomes are compatible with (but do not affirm) a clinical benefit resulting from the use of Ginkgo, the application of a more objective system of assessment would be able to provide firm proof.
It is proposed, therefore, that an objective, computer-based testing system for assessment of clinical improvement in volunteers and patients administered Ginkgo (such as CANTAB) would provide the convincing evidence currently being sought by patients, carers, physicians, legislators and the pharmaceutical industry.
Source: J Pharm Pharmacol 1999 May;51(5):535-41. Cambridge Research Institute, School of Applied Sciences.
PMID: 10411212, UI: 99337019