Experts estimate there are at least 30 million people who are living with dementia worldwide. By the year 2050, they say there will be as many as 100 million facing the disease. So far research into a cure has been unsuccessful. VOA's Melinda Smith has details of the latest study on an ancient herbal supplement, which has shown some promise in previous studies.
Betty Haughin is one of 3,000 elderly participants in a study to see whether the herbal extract ginkgo biloba might help improve memory.
She is already familiar with the devastation that dementia can cause. Her husband Ken died in 2004, after a long struggle with Alzheimer's disease, the most common form of dementia.
"The spirit just goes out of him and the joy of living - you're sick. And you don't remember things, and that makes you angry, because you want to be with it," Haughin said. "It's just a descent into sadness."
Betty Haughin and the other elderly participants, aged 75 and over, were given 120 milligrams of ginkgo biloba or a placebo twice a day.
Some had mild cognitive impairment. Others tested with normal brain functioning.
Dr. Steven DeKosky was the lead researcher on the study which proved to be disappointing.
"The test results showed us that under these circumstances, ginkgo doesn't appear to have any effect of slowing down thinking changes in late life," he said.
The Journal of the American Medical Association also warned that ginkgo biloba may be harmful.
A slightly larger number of the elderly patients experienced strokes, and those with cardiovascular disease were at greater risk of dementia.
Dr. DeKosky says he and the other scientists will continue to search for treatment that will slow the progress of dementia.
"Delaying the onset of the disease for 10 years would effectively eliminate it from the population," he said.
Dr. DeKosky has acknowledged that one flaw in the study was no independent verification that patients actually took their pills.
But there is another study of the herbal extract underway in France. Results of that study, he says, could be further proof that ginkgo biloba will not help.
Some video courtesy of Journal of the American Medical Association