Study: Ginkgo fails to prevent Alzheimer’s

Long touted as an elixir of eternal mental acuity, the herbal extract ginkgo biloba does not prevent or delay the progression of dementia or Alzheimer’s disease, according to a clinical trial reported Tuesday involving thousands of volunteers ages 75 to 96.

The subjects swallowed round, reddish tablets twice a day for an average of more than six years, but at the end of the study, those who received ginkgo biloba were slightly more likely to be diagnosed with dementia and Alzheimer’s than those who received dummy pills.

The results, published in the Journal of the American Medical Association, are sure to disappoint millions of people who take ginkgo in the hopes of boosting their brainpower and staving off the ravages of dementia and Alzheimer’s, which affect more than 5.2 million Americans. Alzheimer’s passed diabetes two years ago as the sixth-leading cause of death in the U.S., according to the Atlanta-based Centers for Disease Control and Prevention.

“No one is more disappointed that we didn’t have any traction in slowing down the disease than the group that did the study,” said Dr. Steven DeKosky, the neurologist who led the clinical trial.

Mark Blumenthal, executive director of the American Botanical Council, a nonprofit group backed by herbal supplement makers, said the study used the right dose of the right ginkgo extract and gave it a reasonable amount of time to show an effect. The fact that it didn’t help puts ginkgo in good company, he said.

“Let’s keep in mind that to date, no conventional pharmaceutical drug has shown any benefit for either preventing the onset of Alzheimer’s or dementia, or even slowing it down,” he said.

Ginkgo is prescribed by physicians to preserve memory in some European countries, including Germany. In the U.S., supplement makers tout ginkgo biloba’s ability to “improve mental sharpness, concentration, memory and cognitive ability,” according to one purveyor.

Companies say it also promotes blood circulation to the arms, legs and brain, thereby boosting overall physical activity levels. Americans spent $107 million on ginkgo biloba products last year, according to Nutrition Business Journal.

THE STATISTICS

> Of the 3,069 people who enrolled in the study, 1,545 took ginkgo extract; the other 1,524 took placebos.

> By the end of the study, 277 of the people who took ginkgo, or 18 percent, were diagnosed with dementia, compared with 246, or 16 percent, in the placebo group. The ginkgo group also included 257 cases of Alzheimer’s, vs. 220 in the placebo group.

> There was no difference in the rate of strokes, heart attacks and angioplasties.

> The only solid distinction between the two groups was the rate of vascular dementia —- when blood flow to the brain is restricted, often by a stroke. That rate was 0.2 percent among the ginkgo group and only 0.08 percent among the placebo group.