In the News: DHA in Alzheimer's Disease and Age-Related Cognitive Decline

Excerpted from the original article by Dr. Michael Rafii in the Alzheimer’s Disease Cooperative Study (ADCS) newsletter, September 2009.

During the Alzheimer’s Association’s July 2009 International Conference on Alzheimer’s Disease (AD) in Vienna, researchers presented results from large studies of DHA (docosahexaenoic acid), an omega-3 fatty acid found in fatty fish such as salmon and mackerel. DHA is naturally found in the body in small amounts and is the most abundant omega-3 fatty acid in the brain. Previous animal studies and epidemiology studies in humans suggested that DHA might be beneficial in people with AD.

The main study was conducted by the Alzheimer’s Disease Cooperative Study, a fifty-six site clinical-trial consortium supported by the National Institute on Aging. The UW ADRC participated in this study. Persons with mild to moderate Alzheimer’s disease were enrolled in an eighteen-month study comparing DHA and placebo. According to the researchers, treatment with DHA clearly increased blood levels of DHA, and it also increased the levels of DHA in study participants' cerebrospinal fluid which suggested an increase in the brain levels of DHA. However, overall, DHA treatment did not slow the rate of change on tests of mental function; although it appeared that study participants without the APOE-ε4 gene who received DHA had a slower rate of decline on some tests of mental function.

The lead researcher for this study, Joseph Quinn, MD, at Oregon Health and Science University, said, "These trial results do not support the routine use of DHA for patients with Alzheimer's."

"This study—and other recent Alzheimer's therapy trials—raise the possibility that treatments for Alzheimer's must be given very early in the disease for them to be truly effective," said William Thies, PhD, the Chief Medical and Scientific Officer at the Alzheimer's Association. "For that to happen, we need to get much better at early detection and diagnosis of Alzheimer's, in order to test therapies at earlier stages of the disease and enable earlier intervention."

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