NATIONAL CENTER FOR COMPLEMENTARY AND ALTERNATIVE MEDICINE
Ginkgo Studied for Prevention of Dementia
Ginkgo biloba
© Karen Bergeron
The herb ginkgo (Ginkgo biloba) comes from one of the oldest types of trees in the world and has been part of traditional Chinese medicine for thousands of years. Today, many people who use ginkgo do so with the intent to improve their memory or prevent dementia.
Results are in from the largest clinical trial ever conducted on ginkgo, the Ginkgo Evaluation of Memory (GEM) study. The researchers found that ginkgo had no significant effect in reducing the development of dementia or Alzheimer's disease in older people. On the safety side, there were no significant adverse effects or increased risk of bleeding in people taking ginkgo.
The multicenter study was led by Steven T. DeKosky, M.D., vice president of the School of Medicine at the University of Virginia in Charlottesville, formerly of the University of Pittsburgh. It was funded by five NIH components: NCCAM; the National Institute on Aging; the National Heart, Lung, and Blood Institute; the National Institute of Neurological Disorders and Stroke; and the Office of Dietary Supplements.
The GEM study focused on whether ginkgo decreased the incidence of all types of dementia and if it had any effect on overall cognitive decline. Functional disability, occurrence of cardiovascular disease, and mortality were also measured.
The 8-year, placebo-controlled trial enrolled over 3,000 participants age 75 or older who were diagnosed with either normal cognition or mild cognitive impairment (volunteers with prevalent dementia were excluded). The active-treatment group received 120 milligrams of ginkgo extract twice daily; the placebo group, an identical-appearing extract. The study's endpoint was the diagnosis of dementia, as determined from standard criteria. Patients with this diagnosis underwent magnetic resonance imaging to identify the type of dementia.
Among future benefits from GEM will be knowledge about how many participants are needed to obtain clinically significant outcome measures and possible insights on subgroups who may be at greater risk for developing dementia. The study also showed that large clinical trials on dementia prevention can be conducted successfully in older adults.
"If older patients are considering using ginkgo for preventing dementia," said Dr. DeKosky, "I urge them to speak with their health care providers about the results of this study and work together to create the best treatment plan. Our results confirm the importance of randomized trials in the development of new therapies for dementia and Alzheimer's disease and in determining therapeutic benefit not only for conventional therapies but also complementary therapies like ginkgo."
For more information, visit nccam.nih.gov/news/2008/111808.htm. You can also read our interview with Dr. DeKosky.
Reference
- DeKosky ST, Williamson JD, Fitzpatrick AL, et al. Ginkgo biloba for prevention of dementia. Journal of the American Medical Association. 2008;300(19):2253–2262.
