"We have to wait for larger studies," Dodge said.
More research is also needed, she said, on why the 7 participants who had strokes or mini-strokes were all on the extract and what that association might be.
Another expert agreed, calling the findings inconclusive.
"The study was really too small to provide conclusive results on the benefits and risks of ginkgo supplement," said Dr. Paul Aisen, director of the Alzheimer's Disease Cooperative Study at the University of California, San Diego.
"Without a larger study, I would certainly not recommend the use of ginkgo biloba extract in those 85 and over," he said. Overall, he added, the bulk of studies published in the medical literature do not provide enough proof to recommend the herb for preserving memory and cognitive function.
Likewise, the Alzheimer's Association says on its Web site that while the herb may help some people with Alzheimer's disease, further research is needed to find the exact way in which it works. Experts are awaiting the results of a much larger, multi-center trial based at the University of Pittsburgh. That trial compared the effects of the herb with a placebo in 3,000 people to see if ginkgo biloba helped prevent or delay the onset of Alzheimer's disease. The trial ran through 2007, and the results will not be available until some time later.
Dodge's study is published in the Feb. 27 online issue of Neurology.
To learn more about alternative treatments for Alzheimer's, visit the Alzheimer's Association.
SOURCES: Hiroko Dodge, Ph.D., assistant professor, public health, Oregon State University, Corvallis; Paul Aisen, M.D., director, Alzheimer's Disease Cooperative St
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