Herb World News Online

Herb Research Foundation


 Top News  |  World  |  Science  |  Research Reviews  |  Politics  |  Industry  |  Features
Press Releases
CONTACT: Robert S. McCaleb
(303) 449-2265

Negative Ginkgo Study Does Not Negate Strong Body of Positive Evidence

October 5, 2000: Reuters Health Newswire released a story today publicizing a well-controlled Dutch study showing that ginkgo had no effect on age-related memory loss. This negative study has not yet received significant media attention, which is appropriate in light of the abundance of evidence showing a memory-enhancing effect for ginkgo. To put the new study in perspective, HRF wishes to stress that no matter how dramatic - or unimpressive - the results of a single clinical trial are, they must always be considered in light of existing good-quality research.

To summarize the double-blind, randomized, placebo-controlled study, 214 elderly subjects with dementia or Alzheimer's disease took ginkgo or placebo for 12 or 24 weeks. The researchers used neuropsychological tests, clinical assessments, and behavioral self-assessments as outcome measures, but observed no ginkgo effect.

The negative results of the Dutch trial must be weighed against the conclusions of previously published studies - which, taken together, show that ginkgo had a significantly beneficial effect on mental function for tens of thousands of elderly people with age-related memory decline, Alzheimer's disease, or multi-infarct dementia. While this study was accepted for publication in a peer-reviewed journal, so were most of the trials that support gingko's efficacy in treating these conditions.

The scientific literature for even the best-respected remedies contains contradictory findings. As any scientist knows, mixed results can provide patterns that help us refine our theories. For example, most ginkgo studies show no observable effect without at least four weeks of treatment - yet a handful of recent studies in humans and rats have shown that a single large dose of ginkgo can improve reaction time for several hours afterward.

Although a new contradictory result is always interesting, it by no means negates the body of clinical research that has come before it. View an abstract of the Dutch study at www.amgeriatrics.com, volume 48, issue 10.


van Dongen M, van Rossum E, Kessels AGH, et al. The efficacy of ginkgo for elderly people with dementia and age-associated memory impairment: new results of a randomized clinical trial. Journal of the American Geriatrics Society 2000; 48: 1183-94.

 Top News  |  World  |  Science  |  Research Reviews  |  Politics  |  Industry  |  Features

Back to the Herb World News Online Front Page

Visit the Herb World News Archives

© 2003 by Herb Research Foundation, Boulder, CO, USA.