JAMA Logo Omega-3 fatty acid docosahexaenoic acid (DHA), supplements apparently reduce the risk of Alzheimer’s disease (AD). According to a groundbreaking study, mild to moderate AD patients consuming DHA fish oil supplements do not report a decline in the rate of cognitive and functional decline. It was determined that DHA may not be useful for patients with mild to moderate AD.

A randomized, controlled trial was commenced for analyzing if DHA supplementation decreases the rate of cognitive and functional decline AD patients. 402 individuals with mild to moderate Alzheimer’s disease were enrolled from 51 U.S. clinical research sites between November 2007 and May 2009. Authors randomly assigned the study subjects to either receive DHA at a dose of 2 grams/day or a similar placebo. While 60 percent were provided with DHA, 40 percent had to consume a placebo. The results of the study were noted after a period of 18 months.

Authors quote, “Several studies have found that consumption of fish, the primary dietary source of omega-3 fatty acids, is associated with a reduced risk of cognitive decline or dementia. Some studies have found that consumption of DHA, but not other omega-3 fatty acids, is associated with a reduced risk of Alzheimer disease. However, those studies were observational and did not control who received DHA. Animal studies that used DHA showed reductions in Alzheimer-like brain pathology.”

Having employed the Alzheimer’s Disease Assessment Scale (ADAS-cog) and the Clinical Dementia Rating (CDR) sum of boxes, scientists were seemingly able to evaluate alterations in cognitive and functional abilities of the subjects. Also a volumetric magnetic resonance imaging (MRI) was used for analyzing the rate of brain atrophy in a subsample of patients. 295 participants completed the trial among which 171 were on DHA and 124 receiving placebo. The results concluded that DHA does not help reduce the rate of change on ADAS-cog score. After 18 months 7.98 points were supposedly given to the DHA group and 8.27 points for the placebo group.

As per the rate of points change on CDR sum of boxes, 2.93 were for the placebo group and 2.87 for the DHA group. From those included in the MRI substudy 53 belonging to the DHA group and 49 from the placebo group had MRIs at the beginning of the study and at 18 months. Joseph F. Quinn, M.D., of Oregon Health and Science University and the Portland VA Medical Center, Portland, Ore., and colleagues were unable to register any beneficial effect of DHA treatment on total brain volume change during 18 months. It was concluded that DHA use before disease onset probably changes the risk of AD. But later inclusion of the supplement does not restrict dementia.

The study was published in the November 3 issue of JAMA, a theme issue on aging.