TUESDAY, Aug. 20, 2002 (HealthDayNews) -- So, you think that ginkgo can improve your memory? Forget about it.
So says Paul R. Solomon, a professor of psychology at Williams College in Massachusetts who ran a controlled study at a memory clinic and came up with negative results.
"This study shows that when ginkgo is taken following the manufacturer's recommendation by elderly people, it has no effect on learning, memory or related cognitive function," Solomon says.
Pharmacon, the company that makes the product used in the study, disagrees. Ginkgo is a popular, over-the-counter substance sold as a "dietary supplement" to comply with the U.S. Food and Drug Administration's prohibition that it be marketed as a drug.
"Our reaction is that this study certainly questions the efficacy of ginkgo, but we don't think it negates the vast body of clinical evidence that has been amassed over the last 30 years," says Dean M. DiMarco, vice president and general manager of Pharmacon, a division of the German pharmaceutical company Boehringer Ingelheim.
Most of the studies testing ginkgo have gotten positive results, DiMarco maintains, and "there is a statistical chance that one or two of them will show lack of efficacy."
While a majority of the reported studies show "some positive effects," Solomon acknowledges, many of them did not follow the carefully controlled rules needed to satisfy the scientific requirements for proof positive.
Solomon's study was done following those rules. In technical terms it was a randomized, double-blind, placebo-controlled trial, meaning that neither the participants nor the people doing the study knew who was getting the active substance and who was getting a placebo.
The study included 98 men and 132 women age 60 or over, all in good health, who attended the memory clinic run by Solomon in Bennington, Vt. He says the study was done because "we have many patients who come to us complaining of memory problems, and 25 or 30 percent of them are taking ginkgo or related substances." They were attracted by "advertising claims that this helps their memory," he says.
Ginkgo is an extract from the leaves of a tree that is one of the oldest living species. It has been used medically since 2800 B.C. Old Chinese records say it has the power to "benefit the brain" and relieve symptoms of asthma and coughs, among other things.
In the new study, half of the participants got the placebo, while the other half took the recommended dose of Ginkoba, the Pharmacon product -- 40 milligrams three times a day -- for six weeks. All of them took a number of tests of different aspects of mental function, while their performance was also rated by companions.
"The results of this six-week study indicate that ginkgo did not facilitate performance on standard neuropsychological tests of learning, memory, attention and concentration or naming and verbal fluency in elderly adults without cognitive impairment," says a report in tomorrow's Journal of the American Medical Association. "The ginkgo group also did not differ from the control group in terms of self-reported memory function or global rating by spouses, friends and relatives."
The supplement did help in one way, Solomon says. Some people taking it felt their mental function improved. However, the same was true of the people taking the placebo, he says. It could be argued that longer use of the product would give positive results, but ads say it will start to help after just four weeks, Solomon notes.
An impartial assessment is offered by the Alzheimer's Disease Education and Referral Center of the National Institute on Aging. It cites one study that appears to have given positive results, but notes that a high dropout rate and other factors make the results questionable. At the moment, the center says, there is not enough research to indicate that ginkgo is safe and effective as a memory booster.
What To Do
You can get a roster of studies showing positive results from Boehringer Ingelheim and a government evaluation from the National Institute on Aging.
