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Dec. 29, 2009 - The hot-selling herbal supplement ginkgo biloba doesn't slow age-related mental decline, a six-year clinical study shows.
The study has already shown that ginkgo does not prevent dementia or Alzheimer's disease in the elderly.
Now study leader Steven T. DeKosky, MD, and colleagues have sifted through the data to look for some sign that ginkgo might slow mental decline in healthy, aging individuals -- or, perhaps, in those already showing the first signs of cognitive impairment.
No such sign was found.
"Compared with placebo, the use of Ginkgo biloba, 120 mg twice daily, did not result in less cognitive decline in older adults with normal cognition or with mild cognitive impairment," the researchers conclude.
The problem wasn't potency. The study used the standardized ginkgo extract from Schwabe Pharmaceuticals that is regulated and sold as a medication in Germany.
And the problem wasn't rigorous testing. Twice a year, the 72- to 96-year-old study participants received a battery of tests that measured various aspects of mental function, including memory, attention, visuospatial abilities, language, and executive function.
Regardless of which mental function was measured, the tests show gingko doesn't help slow cognitive decline.
The findings echo those of a 2009 Cochrane Review of ginkgo studies that identified no cognitive benefit from the supplement.
The Council for Responsible Nutrition, a group representing the supplement industry, suggests that the DeKosky study "should not be viewed as the final work" on ginkgo.
In a written statement, Douglas MacKay, ND, CRN vice president for scientific and regulatory affairs, notes that cognitive decline has many causes and that neither ginkgo nor any other single treatment is a magic bullet.
"As a former practicing licensed naturopathic doctor, I have had the benefit of working with patients and have seen first-hand how Ginkgo biloba can be effective in improving cognitive function," MacKay says. "I would continue to recommend Ginkgo biloba to older adults as a safe, effective option for supporting cognitive health and would encourage consumers to talk to their own healthcare professional about what is right for them."
DeKosky and colleagues report their findings in the Dec. 23/30 issue of The Journal of the American Medical Association.