DHA 'fish oil' supplements do not seem to slow cognitive, functional decline in Alzheimer's disease

November 02, 2010

Patients with mild to moderate Alzheimer's disease (AD) who received supplementation with the omega-3 fatty acid docosahexaenoic acid (DHA), believed to possibly reduce the risk of AD, did not experience a reduction in the rate of cognitive and functional decline, compared to patients who received placebo, according to a study in the November 3 issue of JAMA, a theme issue on aging.

Joseph F. Quinn, M.D., of Oregon Health and Science University and the Portland VA Medical Center, Portland, Ore., presented the findings of the study at a JAMA media briefing at the National Press Club.

"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," the authors write. However, those studies were observational and did not control who received DHA. Animal studies that used DHA showed reductions in Alzheimer-like brain pathology.

Dr. Quinn and colleagues conducted a randomized, controlled trial to examine whether DHA supplementation would slow the rate of cognitive and functional decline in individuals with Alzheimer's disease. The study, which was conducted between November 2007 and May 2009 at 51 U.S. clinical research sites, included 402 individuals with mild to moderate Alzheimer's disease. Participants were randomly assigned to DHA at a dose of 2 grams/day or to identical placebo (60 percent were assigned to DHA and 40 percent were assigned to placebo). Duration of treatment was 18 months. Changes in cognitive and functional abilities were assessed with the Alzheimer's Disease Assessment Scale

(ADAS-cog) and the Clinical Dementia Rating (CDR) sum of boxes. Rate of brain atrophy was also determined by volumetric magnetic resonance imaging (MRI) in a subsample of participants.

A total of 295 participants completed the trial while taking study medication (DHA: 171; placebo: 124). The researchers found that supplementation with DHA had no beneficial effect on rate of change on ADAS-cog score, with the rate of average change in the score over 18 months being 8.27 points for the placebo group and 7.98 points for the DHA group. The rate of points change on CDR sum of boxes over 18 months was 2.93 for the placebo group compared with 2.87 for the DHA group.

Among the individuals participating in the MRI substudy (102 had MRIs at the beginning of the study and at 18 months [DHA group: 53; placebo group: 49]), an analysis showed no effect of DHA treatment on total brain volume change during 18 months.

"In summary, these results indicate that DHA supplementation is not useful for the population of individuals with mild to moderate Alzheimer disease," the authors write.

The researchers add that "because part of the rationale for the trial was epidemiological evidence that DHA use before disease onset modifies the risk of Alzheimer disease, 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."

(JAMA. 2010;304[17]:1903-1911. Available pre-embargo to the media at www.jamamedia.org)

Editor's Note: Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

Please Note: For this study, there will be multimedia content available, including the JAMA Report video, embedded and downloadable video, audio files, text, documents, and related links. This content will be available at 10 a.m. ET Tuesday, November 2 at www.digitalnewsrelease.com/?q=jama_3763.

Editorial: Treatment of Alzheimer Disease and Prognosis of Dementia

In an accompanying editorial, Kristine Yaffe, M.D., of the University of California, San Francisco and Veterans Affairs Medical Center, San Francisco, comments on the findings of this study.

"This trial adds to a growing literature that treatment with DHA does not improve symptoms of AD. Although several observational studies reported that diets rich in fish or supplements with omega-3 fatty acids were associated with reduced risk of developing AD, most randomized clinical trials for treatment of AD or mild cognitive impairment or in healthy elderly individuals have not found a beneficial effect."
-end-
(JAMA. 2010;304[17]:1952-1953. Available pre-embargo to the media at www.jamamedia.org)

Editor's Note: Please see the article for additional information, including financial disclosures, funding and support, etc.

To contact Joseph F. Quinn, M.D., call Ken Olsen at 503-494-8231 or email olsenke@ohsu.edu. To contact editorial author Kristine Yaffe, M.D., call Steve Tokar at 415-221-4810, ext. 5202 or email steve.tokar@ncire.org.

For more information, contact JAMA/Archives Media Relations at 312/464-JAMA (5262) or e-mail mediarelations@jama-archives.org.

The JAMA Network Journals

Related Alzheimer Disease Articles from Brightsurf:

Potential link for Alzheimer's disease and common brain disease that mimics its symptoms
A new study by investigators from Brigham and Women's Hospital uncovered a group of closely related genes that may capture molecular links between Alzheimer's disease and Limbic-predominant Age-related TDP-43 Encephalopathy, or LATE, a recently recognized common brain disorder that can mimic Alzheimer's symptoms.

Uncovering Alzheimer's disease
Characterized by a buildup of amyloid plaques in the brain, Alzheimer's is an irreversible disease that leads to memory loss and a decrease in cognitive function.

Viewpoint: Could disease pathogens be the dark matter behind Alzheimer's disease?
In a lively discussion appearing in the Viewpoint section of the journal Nature Reviews Neurology, Ben Readhead, a researcher in the ASU-Banner Neurodegenerative Disease Research Center at the Biodesign Institute joins several distinguished colleagues to discuss the idea that bacteria, viruses or other infectious pathogens may play a role in Alzheimer's disease.

Coordination chemistry and Alzheimer's disease
It has become evident recently that the interactions between copper and amyloid-╬▓ neurotoxically impact the brain of patients with Alzheimer's disease.

How Alzheimer's disease spreads through the brain
Tau can quickly spread between neurons but is not immediately harmful, according to research in mouse neurons published in JNeurosci.

A protective factor against Alzheimer's disease?
Researchers at the German Center for Neurodegenerative Diseases (DZNE) and the Institute for Stroke and Dementia Research (ISD) at the University Hospital of the Ludwig-Maximilians-Universit├Ąt (LMU) in Munich have found that a protein called TREM2 could positively influence the course of Alzheimer's disease.

An alternate theory for what causes Alzheimer's disease
Alzheimer's disease, the most common cause of dementia among the elderly, is characterized by plaques and tangles in the brain, with most efforts at finding a cure focused on these abnormal structures.

Alzheimer's: How does the brain change over the course of the disease?
What changes in the brain are caused by Alzheimer's disease?

Possible pathway to new therapy for Alzheimer's disease
Researchers have uncovered an enzyme and a biochemical pathway they believe may lead to the identification of drugs that could inhibit the production of beta-amyloid protein, the toxic initiator of Alzheimer's disease (AD).

Promising novel treatment against Alzheimer disease
New research conducted at the Lady Davis Institute (LDI) at the Jewish General Hospital reveals that a novel drug reverses memory deficits and stops Alzheimer disease pathology (AD) in an animal model.

Read More: Alzheimer Disease News and Alzheimer Disease Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.