Ginkgo biloba may be the inspiration for some beautiful German poetry, but its value as a preventative medicine against Alzheimer's disease appears to be lacking, according to a new study.
The extract of the ginkgo tree has enjoyed popular reputation as a natural way to shore up memory, and small studies in animals suggest that it can improve cognitive function. But recent large trials in humans, including a study published in The Lancet Neurology on Thursday, have found that the plant doesn't seem to have the power to halt the progress of dementia and Alzheimer's disease.
In their paper, French scientists reported the results of a trial of gingko biloba involving nearly 3000 people 70 years or older who had complained of memory problems to their physicians.
1406 of the trial participants took gingko biloba extract twice a day, and 1414 were dosed with placebo. After five years, 4% of the people taking ginkgo biloba showed signs of Alzheimer's disease, a s compared to 5% in the placebo group - a difference of only 12 people, and not a statistically significant result. The ginkgo group didn't appear to derive any benefit from the treatment.
"While our trial appears to have shown that regular use of ginkgo biloba does not protect elderly patients from progression to Alzheimer's disease, more studies are needed on long term exposure," lead author Bruno Vellas, a researcher at Hopital Casselardit, said in a statement Wednesday.
The results from the French trial are similar to the findings in a trial conducted in the US and published in the Journal of the American Medical Association in 2009.
USC neurologist Lon Schneider, who wrote an accompanying commentary in the journal, pointed out that the French researchers, in drawing from a pool of patients that complained of memory problems, were trying to increase the likelihood that they would see larger numbers of patients progress to dementia.
But in the study, the number of people that developed dementia was less than half the expected number, possibly due to the 'healthy participant effect' - people less at risk for Alzheimer's disease tend to be more likely to volunteer for trials, according to Schneider.
Schneider also cites studies that show adopting healthy behaviors is a more sure-fire way for people to lower their Alzheimer's risk. A 2008 paper in the Journal of Cellular and Molecular Medicine found that people who carry a gene variant called ApoE4, which increases risk for Alzheimer's disease, could reduce their risk down to near normal levels by becoming physically active and cutting down on smoking, drinking, and eating fatty foods.
"Some users will rationalise that, in the absence of effective treatments, ginkgo biloba could still possibly help and, appearing safe, will not harm them," Schneider wrote. "Other users of ginkgo biloba, however, might now consider letting it go."
SOURCE: Vellas et al. "Long-term use of standardized ginkgo biloba extract for the prevention of Alzheimer's disease (GuidAge): a randomized placebo-controlled trial."; Schneider, Lon. "Ginkgo and AD: key negatives and lessons from GuidAge." The Lancet Neurology published online 6 September 2012.