CRN Critiques JAMA’s Negative DHA Alzheimer’s Study for Not Focusing on Prevention

November 2, 2010

The Council for Responsible Nutrition (CRN; Washington, DC) today voiced its concern over a new Journal of the American Medical Association study, stating that the study did not consider the preventive role of omega-3 docosahexaenoic acid (DHA) in cognitive decline, but rather used DHA to try to treat those already suffering from Alzheimer’s disease.

The JAMA study featured 402 subjects (295 of whom completed the study) with mild to moderate Alzheimer’s disease. The randomized, double-blind trial administered either 2 g of algae-derived DHA per day, or placebo. (60% of subjects received DHA; 40% received placebo.) Cognitive changes were measured using the Alzheimer’s Disease Assessment Scale (ADAS-cog) and the Clinical Demetia Rating (CDR) system. Magnetic resonance imaging was also performed on some participants. The 18-month study took place between November 2007 and May 2009 at 51 clinical research sites in the United States.

The researchers found that DHA showed no beneficial change compared with placebo. Using ADAS-cog, DHA subjects showed an average change of 7.98 points, while the placebo group changed 8.27 points. Using CDR, the treatment group was determined to have had a 2.87 rate-of-points change, while the placebo group’s score was 2.93. The MRI group (53 DHA subjects and 49 placebo subjects) showed no DHA effect on total brain volume change.

“In summary, these results indicate that DHA supplementation is not useful for the population of individuals with mild to moderate Alzheimer’s disease,” wrote the authors.

The authors, however, stated they do not rule out epidemiological evidence that suggests DHA may be more effective when administered prior to the onset of Alzheimer’s in a preventive fashion.

In its statement, CRN mirrored this thought, critiquing the study’s use of DHA as a disease treatment.

“The concern with this study is that it focused on supplementing DHA in individuals who were currently coping with Alzheimer’s disease. It didn’t answer the question of whether DHA—taken over long periods of time and several years prior to disease onset—could have helped prevent these participants from developing the disease,” said Duffy MacKay, ND, vice president of CRN’s scientific and regulatory affairs.

The association also pointed to previous studies suggesting that DHA, combined with eicosapentaenoic acid (EPA), when administered over longer periods of time, may reduce the risk of dementia and Alzheimer’s disease. CRN also says that studies have pointed to DHA as an essential building block for brain tissue.

Read more about the study, published in the November 3 issue of JAMA: here and here.