Just over a year after a study showed that the herb doesn't prevent dementia and Alzheimers disease, a new study from the same team of researchers has found no evidence that ginkgo reduces the normal cognitive decline that comes with aging.
Should you take ginkgo to slow down the effects of age on the brain? "The answer appears to be 'no,'" says the lead author of the study, Steven T. DeKosky, MD, the vice president and dean of the School of Medicine at the University of Virginia.
In the new study, the largest of its kind to date, Dr. DeKosky and his colleagues followed more than 3,000 people between the ages of 72 and 96 for an average of six years. Half of the participants took two 120-milligram capsules of ginkgo a day during the study period, and the other half took a placebo.
The people who took ginkgo showed no differences in attention, memory, and other cognitive measures compared to those who took the placebo, according to the study, which was published today in the Journal of the American Medical Association.
Dr. DeKosky also led the 2008 study that looked at the effects of ginkgo on dementia and Alzheimer's disease. Both studies are part of the larger Ginkgo Evaluation of Memory (GEM) study, which is funded by the National Center for Complementary and Alternative Medicine and the National Institute on Aging.
Ginkgo biloba is among the most popular dietary supplements for brain health. In 2007, Americans spent $107 million on ginkgo, which has been used for more than 1,600 years to promote mental acuity, says Dr. DeKosky. (Ginkgo has also been used to treat a range of maladies including asthma and ringing in the ears.)
When ginkgo first became popular in the 1980s and 1990s, researchers and consumers alike were optimistic about the effects of ginkgo on cognition, but its reputation has suffered in recent years, says Joshua Steinerman, MD, assistant professor of neurology at Montefiore Medical Center in the Bronx, N.Y.
“Early studies seemed to show that there might be some cognitive improvement, but those were typically smaller studies and not as well designed," says Dr. Steinerman, who did not participate in the current study. "More recent studies, including the GEM study, are large and well controlled, and have showed no consistent positive effect on slowing the rate of cognitive decline.”
Even so, Dr. DeKosky says he and his colleagues were surprised to find that ginkgo failed to produce any benefit, given how long the herb has been used and how many people swear by it. “We figured that if [ginkgo] was still in use and still endorsed by peopleeven if its only your grandmotherit probably does have some basis to it,” he says.
The study's findings don't mean that people should stop taking ginkgo (as long as they do so in safe doses, under the supervision of a physician), says Dr. Steinerman. But, he adds, "I certainly wouldnt recommend that anyone start it."
Ginkgo may not be effective, but there are many other healthy habits you can try to help keep your brain healthy:
•Exercise your mind. Activities that stimulate the brainsuch as learning a new language, playing brain-teasing games, or doing crossword puzzlesappear to delay the onset of dementia, says Dr. Steinerman, although its still unclear if they can actually prevent or slow down cognitive decline. These activities can't hurt, however, and many new brain games for computers and video-game consoles (such as Brain Age and Brain Challenge) provide more options than ever before.
•Exercise your body. The evidence linking physical activity with slower cognitive decline is convincing, says Dr. Steinerman. Animal studies have shown that exercise targets a part of the brain directly related to memory and aging, and other research suggests that even moderate exercisea weekly bike ride, sayis associated with maintaining cognitive function.
•Manage stress. Staying as stress-free as possible is essential for maintaining your sanity in the short term, but it may also be important to your long-term brain function. “High levels of stress can kill nerve cells in the most important areas of the brain for memory,” says Dr. Steinerman. “Stress can actually accelerate cognitive decline and increase the risk for Alzheimers."
•Eat right. Diets that are good for the heart are also believed to have beneficial effects on the brain, says Dr. Steinerman. Research suggests that a diet rich in fish, fruits, vegetables, and healthy fats may promote brain health. A 2009 study in the Archives of Neurology, for instance, found that people who adhered most closely to the Mediterranean Diet had a 28% lower risk for mild cognitive decline than those who didn't stick to the diet.
•Make friends. Having a rich social life may help delay cognitive decline (although it may not reverse it). Studies have shown that “more social contacts and more social interactions [appear] to be present in people who [don't] develop dementia,” says Dr. DeKosky. “Your number of social contacts [translates] into some kind of brain change” that affects your risk of developing dementia, he says.
None of these habits is a silver bullet, however, and they are probably most effective in combination, says Dr. Steinerman.
Researchers will continue to study the effects of supplements such as ginkgo in hopes of one day creating a drug to prevent and cure cognitive decline, says Dr. DeKosky, but in the meantime patients should incorporate habits such as these into their daily lives.
“Were working on the next generation of drugs,” he says, “[but] I think the brain can be strengthened by doing things other than waiting for a pill to take.”