Seattle/LocalHealthGuide

Gingko biloba, a popular herbal preparation used to prevent or treat memory problems, failed to prevent the onset of dementia or Alzheimer’s diseases in a large study of older men and women.

The study appears in today’s issue of JAMA, the Journal of the American Medical Association

Gingko biloba is one of the most popular herbal products with worldwide annuals sales of over $249 million.

More than 3,000 men and women age 75 or older participated in the study, called the Ginkgo Evaluation of Memory (GEM) trial.

Most of the participants had normal cognitive function, but a subset, 482, had mild cognitive deficits.

The participants were randomly assigned to take either 125-mg of Ginkgo extract twice a day or a placebo.The participants were followed for a median of just over six years.

Neither the researchers or the participants knew who was taking the herb or the placebo.

At the end of the study, the researchers found that participants in each group developed dementia at roughly the same rate: 3.3 per 100 per year among those taking Gingko and 2.9 per 100 per year among those taking the placebo, a difference that was not statistically significant.

Overall, 523 of the study participants developed dementia, 246 (16.1%) in the Gingko group and 277 (17.9%) in the placebo group, again, a difference that was not statistically significant.

The herbal product also had no effect on the rate of progression to dementia in those participants who had mild cognitive impairment at the outset of the study.

In an editorial accompanying the JAMA study, Dr. Lon S. Schneider of the University of Southern California, Los Angeles writes, “The GEM study adds to the substantial body of evidence that Gingko biloba extract as it is generally used does not prevent dementia in individuals with or without cognitive impairment and is not effective for Alzheimer’s disease.” 

The lead author of the study was Dr. Steven T. DeKosky, who was at the University of Pennsylvania at the time of the study and is now at the University of Virginia.

Local Seattle researchers Richard Kronmal, professor of biostatistics, and Annette L. Fitzpatrick, a research associate professor at the University of Washington School of Public Health and Community Medicine were also part of the research team.

To learn more:

• Read the paper and editorial in the journal JAMA (fee or subscription may be required).
• Read the National Center for Complementary and Alternative Medicine page on Gingko.
• Visit the National Library of Medicine’s information page on Gingko.
• Visit the Ginkgo Evaluation of Memory study website, which has information about the study and Gingko biloba.