A compound in red wine that's been theorized to have anti-aging effects appears to be safe for people with Alzheimer's disease, and may point to a new way to treat the disease, early research suggests.
In the study, about 120 people with Alzheimer's disease took either a medication made from the compound, called resveratrol, or a placebo, daily for a year. The dose of resveratrol was high — about the equivalent of the amount found in 1,000 bottles of red wine, the researchers said.
Resveratrol appeared to have an effect on levels of a protein called amyloid-beta40, or Abeta40. Usually, as Alzheimer's disease gets worse, the levels of Abeta40 decline in a person's cerebrospinal fluid (CSF), which surrounds the brain and spinal cord. Researchers think this decline occurs because Abeta40 builds up in the brain insteadof the CSF, leading to symptoms of Alzheimer's disease.
People in the study who took a placebo had a decline in Abeta40 in their spinal fluid during the study period, but those who took resveratrol had little or no change in their levels of Abeta40, the researchers said.
This finding suggests that the resveratrol treatment may have led to less Abeta40 deposits in the brain, but the researchers will need to confirm this in future studies that look at levels of the amyloid protein in the brain. So currently, doctors don't know if resveratrol affects the progression of the disease.
"I'm not recommending that people go out and buy resveratrol and start taking it," said study researcher Dr. R. Scott Turner, director of the Memory Disorders Program at Georgetown University Medical Center in Washington, D.C. "We need further studies to see if it really does have a benefit," Turner said. [4 Foods That Are Good Sources of Resveratrol]
Still, Turner said the new findings suggest that resveratrol may act through a brain pathway different from the one typical Alzheimer's drugs do. Instead of targeting amyloid proteins directly, as many Alzheimer's treatments do, resveratrol targets them indirectly, Turner said.
"It's showing us a new mechanism, or a new pathway, towards Alzheimer's treatments," Turner said. "This is targeting amyloid in an indirect way," he said. Researchers think that resveratrol activates proteins called sirtuins, which are also activated by calorie restriction, and may have anti-aging effects.
The new study did not include enough people to definitively determine whether resveratrol had an effect on symptoms of Alzheimer's disease. But participants did take five cognitive tests, and most showed that there was no difference in thinking abilities between the group that took resveratrol and the group that took placebo.
However, one test showed that people who took resveratrol showed less decline in daily activities such as cooking, getting dressed and using a telephone, compared with the placebo group. A larger study is needed to confirm the finding and better examine the effects of resveratrol on Alzheimer's symptoms, Turner said.
Some scientists had argued that resveratrol would not be able to cross the blood-brain barrier, a structure that prevents some substances and drugs from getting into the brain. But the new study found that resveratrol did, indeed, cross the blood-brain barrier — the researchers found low concentrations of the compound in the CSF, Turner said.
One unexpected finding was that people who took resveratrol experienced more brain shrinkage over the course of the study, compared with people who took the placebo. The meaning of this finding is not clear, Turner said, and it's possible that the brain shrinkage was due to reduced brain swelling in the patients who took resveratrol.
The most common side effects of resveratrol were nausea and diarrhea. Patients who took resveratrol also lost about 2 lbs. (0.9 kilograms) over the course of the year, whereas patients in the placebo group gained about 1 lb. (0.45 kg). Weight loss is not something that is desirable in Alzheimer's disease patientsbecause patients tend to lose weight anyway with the disease, Turner said. So if resveratrol ends up being used in patients, they may need to take supplements to prevent weight loss, he said.
Dr. Marc Gordon, chief of neurology at Zucker Hillside Hospital in Queens, New York, said the new study shows that "resveratrol gets into the brain, and it seems to have some sort of measurable effect," but it's not clear what these effects mean. "I don’t think this is any evidence that resveratrol is necessarily beneficial" for Alzheimer's disease, Gordon said.
James Hendrix, director of global science initiatives at the Alzheimer's Association, said the findings were "encouraging," because the stabilization of Abeta40 means that patients who took resveratrol may not be declining as quickly. But the findings beg the question of what would happen in a larger study that was done over a longer period, Hendrix said.
There's a need to be cautious because other drugs that have looked promising for Alzheimer's in early trials did not end up showing a benefit, Hendrix said.
The new study is published online today (Sept. 11) in the journal Neurology.