Ginkgo Biloba

Ginkgo Biloba and Alzheimer’s

In 1998 Barry S. Oken of Oregon Health Sciences University and his colleagues considered more than 50 studies involving subjects with mental impairment and selected four that met a conservative set of criteria, including sufficient characterization of the Alzheimer's diagnosis, use of a standardized ginkgo extract, and a placebo-controlled, double-blind design (in which neither the subjects nor the investigators know until the end whether a given patient is receiving the extract or the placebo). Each of these studies showed that the Alzheimer's patients who received ginkgo performed better on various cognitive tests than did patients who received a placebo. Improvements were evident in standardized tests measuring attention, short-term memory and reaction time; the average extent of improvement resulting from ginkgo treatment was 10 to 20 percent.

Oken and his colleagues reported that ginkgo's effect was comparable to that of the drug donepezil, which is currently the treatment of choice for Alzheimer's.

Despite these apparently encouraging findings, though, another recent, large and well-controlled trial of EGb 761 (sponsored by its manufacturer, Dr. Willmar Schwabe Pharmaceuticals in Karlsruhe, Germany) involving patients with a mild or moderate stage of dementia reported no “systematic and clinically meaningful effect of ginkgo” on any of the cognitive tests employed.

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