According to US researchers, omega-3 fatty acid supplements do not help slow memory loss in people with mild to moderate Alzheimer’s disease.
The results of an 18-month government-funded study suggest that taking docosahexenoic acid, or DHA – an omega-3 fatty acid – does not inhibit Alzheimer’s in people who already have the mind-numbing disease.
“These study results do not support the routine use of DHA in Alzheimer’s patients,” said Dr. Joseph Quinn of Oregon Health and Sciences University (OHSU) in Portland, who led the study.
A separate, company-funded, six-month study examining people whose memory was just beginning to slip found that DHA supplements helped restore some of the lost mental acuity.
“The benefit roughly corresponds to the learning and memory skills of a person three years younger,” says Martek researcher Karin Yurko-Mauro.
Both studies, which will be presented at an international meeting of the Alzheimer’s Association in Vienna, show the difficulty of treating Alzheimer’s disease.
The disease, which affects 26 million people worldwide, leads to memory loss, confusion, inability to take care of oneself, and ultimately death.
Taken together, the results, along with other studies, suggest that treatment for Alzheimer’s must begin early in the disease, before sticky amyloid plaques start to form toxic clumps in the brain.
“It may be that … by the time you have Alzheimer’s, it may be too late,” says Dr. Ronald Petersen, director of Alzheimer’s research at the Mayo Clinic in Rochester, Minnesota.
Studies in mice and humans had shown that diets high in DHA, an omega-3 fatty acid found in fatty cold water fish, can dramatically slow Alzheimer’s disease, and hopes have been for DHA as a potential new treatment large.
DHA occurs naturally in the body in small amounts and is the most abundant omega-3 fatty acid in the brain.
In the OHSU study, Quinn and colleagues compared DHA supplements with a placebo in 402 people with mild to moderate Alzheimer’s disease. Although DHA levels increased in the blood, the team found no change in two generally accepted Alzheimer’s tests.
However, the study suggested some benefit in people with Alzheimer’s who do not have the ApoE4 gene, which is known to increase Alzheimer’s risk. Quinn calls the finding “fascinating” because other studies have shown different response rates based on this gene, and says future studies should investigate this.
In the six-month Martek study, researchers looked at the effects of a daily dose of 900 milligrams of DHA on 485 healthy people, mean age 70, who had a mild memory problem. The subjects in this study were tested using a computer memory test.
After six months, those taking DHA made far fewer mistakes than those in the placebo group. The effect was “almost double,” says Yurko-Mauro.
Petersen, a former vice chairman of the United States Alzheimer’s Association, said the study was promising but needs confirmation before healthy people start taking DHA supplements.
“The association does not recommend the use of DHA for normal elderly people based on this study,” he says.
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