Gingko Biloba Fails Memory Test

(November 19, 2008) - The herb Ginkgo biloba failed an almost 10-year test to see if it could prevent serious memory loss, such as dementia and Alzheimer's disease. (Read about "Dementia" "Alzheimer's Disease") Use of the herb Ginkgo biloba (Read about "Herbal Precautions"), claimed to have beneficial effects on memory and cognition, was not effective in reducing the rate of dementia or Alzheimer's disease among more than 1,500 elderly study participants after several years of use, according to a study in the Journal of the American Medical Association.

Dementia, especially Alzheimer's disease (AD), currently affects more than 5 million people in the United States and is a leading cause of age-related disability and long-term care placement, according to background information in the article. Ginkgo biloba is prescribed in some areas of the world for preservation of memory (Read about "Complementary & Alternative Medicine"); however, there are no medications approved for prevention of dementia in the U.S., and to date, no clinical trial of adequate design and size has evaluated the safety and effectiveness of Ginkgo biloba in the prevention of dementia.

Researchers enlisted over 3,000 people over the age of 75. Most of them had normal memory function at the start of the study, which lasted from 2000 until this year. Approximately 15 percent had what is called mild cognitive impairment (MCI). About half of the group received a twice-daily dose of 120-mg extract of Ginkgo biloba, the other half a placebo. Everyone was assessed every 6 months for dementia.

During the study 523 participants were diagnosed with dementia, 246 (16.1 percent) in the placebo group and 277 (17.9 percent) in the Ginkgo biloba group. Of the total dementia cases, 92 percent were classified as possible or probable AD, or AD with evidence of vascular disease of the brain. The rate of total dementia did not differ between participants assigned to Ginkgo biloba vs. placebo (3.3 dementia cases/100 persons, per year among persons getting the Ginkgo biloba vs. 2.9/100 persons, per year among persons getting the placebo). The rate of Alzheimer-type dementia also did not differ between the two treatment groups (3.0/100 persons, per year vs. 2.6/100 persons, per year). Ginkgo biloba also had no effect on the rate of progression to dementia in participants with MCI.

"Based on the results of this trial, Ginkgo biloba cannot be recommended for the purpose of preventing dementia," the authors write.