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Ginkgo biloba – No Effect

Posted in Science Based Medicine by Skepdude on January 3, 2010


Another one bites the dust.

The National Center for Complementary and Alternative Medicine (NCCAM) is generally a waste of taxpayer money, but they have sponsored several well-designed large trials of popular herbal supplements. And one by one these studies have shown these popular products, such as echinacea for the common cold, to be ineffective.

To add to the list, published in JAMA this week are the results of the largest and longest trial to date of Gingko biloba for the improvement of cognitive function and to treat, prevent, or reduce the effects of Alzheimers disease or other dementia. The results of the study are completely negative.

The study was very rigorous – a consensus trial designed to address all the criticisms of prior smaller studies. It was a direct comparison of Gingko biloba at 120mg twice a day, double blind, randomized, multi-center trial involving 3019 subjects aged 72-96 for a median of 6.1 years. Subjects were followed with standardized tests of cognitive function.

The results are easy to report – every measure showed no difference between G biloba and placebo. There was no difference in cognitive function, risk of developing dementia, rate of progression of dementia or normal cognitive decline with aging. Usually such studies involve some random noise in the results, especially when several outcomes are measured. But with such a large study, random fluctuations should average out, and that is exactly what happened.


Important Studies page update

Posted in Skepdude by Skepdude on January 3, 2010

The Important Studies page has been updated to include the latest study on Ginko Biloba, the herb that purportedly helps with cognitive decline illnesses in older adults, which came back with absolutely negative results. It appears ginko is gunko!

No Benefit from Gingko

Posted in Neurologica by Skepdude on November 26, 2008

Gingko biloba is widely used as a supplement (even though it is really an herbal drug) to improve memory to help treat or prevent dementia. However, there are no quality trials showing that it is effective. This month in JAMA is published the results of a study that has been going on for the past 8 years looking at ginkgo in elderly patients. I have actually been waiting for these results for a while – a large and fairly definitive trial to end the debates about the significance of the preliminary data we have had so far.

The results did not surprise me – after following 3069 subjects for an average of 6.1 years, the study concluded:

In this study, G biloba at 120 mg twice a day was not effective in reducing either the overall incidence rate of dementia or AD incidence in elderly individuals with normal cognition or those with MCI. (MCI = minimal cognitive impairment)

Therefore the best data we have to date – the results of a very large, well controlled, and highly anticipated trial – gingko does not work. It is always interesting, once such trials have come to light, to then look back at the previous research to see how it compares. What we find is a pattern of suggestively positive studies. Basic science data, for example, showed that gingko extract may reduce amyloid precursor protein in mice – this is a protein that builds up in Alzheimer’s disease. Preliminary clinical trials were mixed but tended to be positive.