Ginkgo Biloba Does Not Help Cognitive Decline

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Ginkgo biloba is one of the most widely used herbal supplements, and older adults specifically use it to prevent cognitive decline. However, results of a new study in the Journal of the American Medical Association (JAMA) state that ginkgo biloba does not slow the rate of cognitive decline in older adults when compared with placebo.

Extracts of the leaves of the ginkgo biloba tree have been used by Chinese medicine practitioners for millennia for various disorders. In more recent times, individuals throughout Europe and North America have used a standardized extract of ginkgo biloba for the treatment of memory and concentration problems, confusion, depression, anxiety, and headache. Although this herbal supplement has gained wide acceptance as a way to help prevent cognitive decline, scientific evidence to support this claim has been questionable. Ginkgo biloba reportedly increases blood supply to the brain by dilating blood vessels and reducing blood viscosity. The herb is also a potent antioxidant.

These latest results come nearly one year after publication by the Cochrane Database of Systemic Reviews report in which investigators reviewed 36 trials that involved ginkgo biloba. Most of the trials were small and lasted less than three months, although nine lasted six months. Overall, the investigators reported that their review showed that while ginkgo biloba seems to be safe, evidence that it provides significant benefit for people with dementia or cognitive impairment is inconsistent and unreliable.

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In the latest JAMA study, the researchers analyzed outcomes from the Ginkgo Evaluation of Memory (GEM) study to determine if the herb had the ability to slow the rate of cognitive decline in older adults who had entered GEM with either normal cognition or mild cognitive impairment. Prior to this study, the GEM trial had not found ginkgo biloba to be effective in reducing the incidence of Alzheimer’s disease or dementia.

A total of 3,069 individuals ages 72 to 96 years who lived in the community were enrolled in the randomized, double-blind, placebo-controlled study. The study was conducted at six academic medical centers across the country between 2000 and 2008. The median follow-up was 6.1 years.

Half of the participants received 120 mg extract of ginkgo biloba twice daily, while the other half received a placebo. The investigators found no evidence that the herb had an impact on cognitive change and no evidence that it affected memory, language, attention, visuospatial abilities, or executive functions.

The Alzheimer’s Association includes information about ginkgo biloba and research results on its website but makes no recommendations either way about its use, although it does state at the beginning of its section on alternative treatments that “there are legitimate concerns about using these drugs as an alternative or in addition to physician-prescribed therapy.” The latest findings of the JAMA study indicate there is no evidence that ginkgo biloba slows the rate of cognitive decline in older adults, and they support the results of previous research.

SOURCES:
Alzheimer’s Association
Birks J, Grimley Evans J. Cochrane Database of Systemic Reviews 2009 Ja 21(1): CD003120
Snitz BE et al. Journal of the American Medical Association 2009; 302(24): 2663-70

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