Dr. Joseph Quinn of Oregon Health and Science University and the Portland Veterans Administration Center in Portland reports patients with mild to moderate Alzheimer's disease receiving supplementation with the omega-3 fatty acid DHA did not experience a reduction in the rate of cognitive and functional decline versus patients who received placebo.
A subgroup of study participants underwent magnetic resonance imaging that showed no effect of DHA treatment on brain volume. Brain shrinkage is associated with Alzheimer's disease.
Quinn and colleagues conducted a randomized, controlled trial at 51 U.S. clinical research sites that gave 402 individuals with mild to moderate Alzheimer's disease either 18 months of DHA at a dose of 2 grams/day or a placebo.
"These results indicate that DHA supplementation is not useful for the population of individuals with mild to moderate Alzheimer disease," the study authors say in a statement. "It remains possible that an intervention with DHA might be more effective if initiated earlier in the course of the disease in patients who do not have overt dementia."
The findings are published in the Journal of the American Medical Association.