TUESDAY, Dec. 29 (HealthDay News) -- Many older adults consume ginkgo biloba, hoping to keep their minds sharp, but a new study finds that the herbal product doesn't stave off cognitive decline.
"Measuring the effect of ginkgo in a big trial in older people, we didn't see any effect of the drug on slowing down or delaying normal age-related changes of cognition," said lead researcher Dr. Steven T. DeKosky, vice president and dean of the University of Virginia School of Medicine in Charlottesville.
"If you are older and thinking 'I'll try ginkgo to preserve brain health,' we have no evidence that it is useful," he said. "I won't take it anymore."
The report, published in the Dec. 23-30 issue of the Journal of the American Medical Association, supports the findings of earlier, smaller studies.
To test ginkgo's effect on cognitive decline, DeKosky's group looked at results from the ginkgo Evaluation of Memory study, which included 3,069 community-dwelling adults 72 to 96 years of age. The participants, who were generally healthy when the study began, either took 120 milligrams of ginkgo or placebo twice a day and were routinely tested for cognitive abilities.
Over more than six years of follow-up, the researchers found no evidence that ginkgo delayed or prevented normal declines in memory, language, attention, visuospatial abilities or executive functions, such as anticipating outcomes and adapting to changing situations and thinking abstractly.
These results remained the same regardless of sex, age, race or education, the researchers noted.
However, ginkgo was safe and no serious side effects were noted, DeKosky added. "The good news is it appeared that it was fairly safe; the bad news was it didn't seem to do anything at least as far as trying to slow down the cognitive changes of aging."
Earlier results from the same study found that ginkgo did not prevent or slow the development of Alzheimer's or other dementias, DeKosky said.
The American Botanical council took issue with the findings, however.
"There are many significant limitations of this study," Mark Blumenthal, council founder and executive director said in a statement.
"First, the data being published this week are drawn from a previous clinical trial which was not designed to determine the decline in cognition. Second, about 40 percent of the subjects dropped out over the six-year duration of the trial; the statistics reported in the study include the dropouts for which no final data are available," Blumenthal said. "Further, the subjects in the study were not monitored for certain cognitive parameters until several years after the trial began, creating difficulty in determining accurately whether they experienced a decline in cognition or not. Also, the age of the subjects is quite advanced, at an average of 79 years at the beginning of the trial. This age group is not typical of the age of both healthy people and those with mild cognitive impairment who use ginkgo for improving mental performance."
Another group, the Council for Responsible Nutrition (CRN), which represents the dietary supplement industry, also had reservations about the study.