April 29, 2013
Much has been made of the promises of the herbal remedy ginkgo biloba for keeping the memory sharp in old age. But a rigorous new study of the herb had disappointing results: ginkgo failed to prevent the onset of Alzheimer’s disease in elderly adults with memory complaints.
The study was a randomized, double-blinded study, the gold standard of medical testing. Neither doctors nor the nearly 3,000 study volunteers, aged 70 and older and living in France, knew who was getting a standardized extract of the ginkgo biloba plant, and who was getting a dummy pill.
All had complained about “senior moments” and minor memory problems at the start of the study, though none had full-blown Alzheimer’s disease. Ginkgo was administered in a dose of 120 milligrams of EGb761, a standardized extract of the plant, twice a day. Participants were given regular medical checkups and memory tests during the two-year study period.
By the end of the study, 61 of the 1,406 seniors getting ginkgo, or about 4 percent, had been diagnosed with probable Alzheimer’s disease, compared to 73 of the 1,414, or about 5 percent, who were getting a placebo. The differences between the two groups were not considered statistically significant, and therefore do not indicate that ginkgo provided any memory-preserving benefits or stopped the progression to Alzheimer’s disease.
The findings, published in the journal Lancet Neurology, are consistent with some earlier research showing that ginkgo may do little to prevent the onset of Alzheimer’s. A rigorous study from 2008 involving thousands of seniors across the United States, for example, found that supplements containing the herb did nothing to ward off the onset of the memory-robbing ailment. Some earlier reports, though, suggested the herb may have some benefits and ease agitation and other psychiatric aspects of the disease.
Ginkgo is a potent antioxidant that, in laboratory studies, helps to protect cells grown in a dish against damage from reactive oxygen molecules. It is thought that antioxidant protection of the cells in the brain may help protect against Alzheimer’s and other forms of dementia. Some research has suggested that ginkgo may have protective activity against beta-amyloid, a toxic protein that builds up in the brains of those with Alzheimer’s.
Physicians in Europe often prescribe ginkgo biloba to help ward off memory loss. And while current Alzheimer’s drugs may ease symptoms temporarily, there are no proven ways to prevent the disease or halt its progression.
Experts also caution that anyone taking ginkgo or products containing the herb should let their doctors know. It may interact with prescription or over-the-counter medications, including aspirin and warfarin, raising the risk of dangerous bleeding. In the current study, there were no differences in side effects among those taking ginkgo versus a placebo.
Source: Bruno Vellas, Nicola Coley, Pierre-Jean Ousset, et al: Long-term use of standardised ginkgo biloba extract for the prevention of Alzheimer’s disease (GuidAge): a randomised placebo-controlled trial. Lancet Neurology, Sept. 6, 2012