Is there any evidence in the medical literature to support the use of gingko biloba for dementia?
Monday, April 12th, 2010Dr. Eric Farbman answers the question, “Is there any evidence in the medical literature to support the use of gingko biloba for dementia?”
Ginkgo biloba is a large shade tree. It was thought to be extinct, but it was rediscovered in China in the 1700s. Today it is used with varying degrees of evidence for many different medical conditions. It is probably the most commonly used herbal product for the prevention of memory loss. Sales of this herb exceed $249 million annually.
Alzheimer’s disease is a devastating disease and the most common dementing illness. It affects more than five million people in the U.S. and this number is expected to rise as the population ages. It is a leading cause of disability in the elderly and one of the primary causes of long-term care placement.
Many people take gingko biloba in an effort to reduce their risk of developing Alzheimer disease. Many health food stores and Web sites market it to that effect. There are no FDA guidelines for the marketing of supplements. Is there any evidence in the medical literature to support the use of gingko biloba for dementia?
Some early studies with gingko biloba seemed to suggest that there might be a mild benefit. These studies may have shown benefit on one of many memory tests. These were also very short-term studies. Because of these early studies, more extensive studies were then performed.
In 2002 a study was published to determine whether there was any memory enhancement in non-demented individuals who took gingko biloba. This study looked at nearly 230 people and there was no benefit seen in any of the many different domains of memory tested. The study authors noted that “gingko biloba provides no measurable benefit in memory or related cognitive function to adults with healthy cognitive function.”
A small study was published in 2008 to determine the feasibility of doing a large gingko biloba trial. It did suggest it was feasible and it also suggested that there might be benefit of taking this herb to slow Alzheimer disease, but it only looked at one area within cognition and feasibility studies by their nature are very small.
Recently the gingko evaluation of memory study was published. This was a very large, well-designed trial that included 3,069 people that was conducted over many years to look at the effect of gingko biloba on slowing the rate of decline of Alzheimer disease. The results, unfortunately, were negative. That is, there was no benefit on gingko biloba either on reducing cognitive decline in normal older adults or in those with mild Alzheimer disease.
These results support other smaller trials that were done around the same time. As a result of this and other trials, gingko biloba cannot be recommended for patients with dementia or for individuals trying to prevent the emergence of dementia. It is natural for patients to be desperate for a cure, but this herb is not the answer.
Eric Farbman, M.D. is a neurologist practicing in Las Vegas, Nevada. He is clinical associate professor of neurology at the University of Nevada School of Medicine.
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