The National Institutes of Health says some studies suggest omega-3 fatty acids found in the oil of certain fish may also benefit the brain by lowering the risk of Alzheimer's disease.

Researchers are looking for 400 participants age 50 and older who have mild to moderate Alzheimer's disease.

The 18-month clinical trial will evaluate whether the omega-3 fatty acid DHA (docosahexaenoic acid) slows the progression of both cognitive and functional decline in people with mild to moderate Alzheimer's, the NIH said in a release.

The trial will be conducted at 51 sites nationwide by the Alzheimer's Disease Cooperative Study. It will be coordinated by the University of California-San Diego and directed by Joseph Quinn, M.D., associate professor of neurology at Oregon Health and Science University.