Omega-3 fatty acid supplements slow cognitive decline in early Alzheimer’s disease

In research published in the October, 2006 issue of the American Medical Association journal Archives of Neurology Yvonne Freund-Levi, MD, of the Karolinska Institutet in Stockholm, Sweden, and colleagues found that omega-3 fatty acid supplementation could slow cognitive decline in patients with very mild Alzheimer's disease.

The team divided 204 patients with Alzheimer’s disease to receive 600 milligrams eicosapentaenoic acid (EPA) and 1.7 grams of docosahexaenoic acid (DHA), or a placebo for six months, followed by a six month period during which both groups received the omega-3 fatty acids. Physical examinations that included blood testing, blood pressure assessment and cognitive function testing were conducted at the beginning of the study, and at six and twelve months.

One hundred seventy-four participants completed the study. While there was no difference in the rate of cognitive decline at the six month mark in the majority of participants, a subgroup of 32 patients with very mild cognitive impairment experienced no change in cognitive function test scores while receiving omega-3 fatty acids, while those who received the placebo experienced a significant decline. This decline was halted when the placebo group received the omega-3-containing supplements during the second half of the study. The group that received omega-3 fatty acids during the first six months experienced no further change during the second six months of the study.

The results support other findings that suggest that a high intake of fish, which is a source of omega-3 fatty acids, is helpful for the prevention but not the treatment of Alzheimer’s disease. As the anti-inflammatory effect of omega-3 fatty acids is a well known property of fish oil, it may play a role in Alzheimer’s disease prevention. Research indicates that there may be a critical period at least two years before the development of dementia in which inflammation is elevated, and is potentially treatable.

“The mechanisms by which omega-3 fatty acids could interfere in Alzheimer's disease pathophysiologic features are not clear, but since anti-inflammatory effects are an important part of the profile of fish oils, they are conceivable also for Alzheimer's disease,” the authors write. “It is possible that when the disease is clinically apparent, the neuropathologic involvement is too advanced to be substantially attenuated by anti-inflammatory treatment."

“Studies in larger cohorts with mild cognitive impairment, including those at risk for Alzheimer's disease, are needed to further explore the possibility that omega-3 fatty acids might be beneficial in halting initial progression of the disease," they conclude.