Docosahexaenoic Acid Supplementation and Cognitive Decline in Alzheimer Disease
A Randomized Trial
- Joseph F. Quinn, MD;
- Rema Raman, PhD;
- Ronald G. Thomas, PhD;
- Karin Yurko-Mauro, PhD;
- Edward B. Nelson, MD;
- Christopher Van Dyck, MD;
- James E. Galvin, MD;
- Jennifer Emond, MS;
- Clifford R. Jack, Jr, MD;
- Michael Weiner, MD;
- Lynne Shinto, ND;
- Paul S. Aisen, MD
- Author Affiliations: Department of Neurology, Oregon Health and Science University, Portland (Drs Quinn and Shinto); Department of Neurosciences, University of California, San Diego (Drs Raman, Thomas, and Aisen, and Ms Emond); Martek Biosciences, Columbia, Maryland (Drs Yurko-Mauro and Nelson); Department of Psychiatry, Yale University, New Haven, Connecticut (Dr Van Dyck); Department of Neurology, School of Medicine, New York University, New York (Dr Galvin); Mayo Clinic, Rochester, Minnesota (Dr Jack); and Department of Radiology, University of California, San Francisco (Dr Weiner).
Abstract
Context Docosahexaenoic acid (DHA) is the most abundant long-chain polyunsaturated fatty acid in the brain. Epidemiological studies suggest that consumption of DHA is associated with a reduced incidence of Alzheimer disease. Animal studies demonstrate that oral intake of DHA reduces Alzheimer-like brain pathology.
Objective To determine if supplementation with DHA slows cognitive and functional decline in individuals with Alzheimer disease.
Design, Setting, and Patients A randomized, double-blind, placebo-controlled trial of DHA supplementation in individuals with mild to moderate Alzheimer disease (Mini-Mental State Examination scores, 14-26) was conducted between November 2007 and May 2009 at 51 US clinical research sites of the Alzheimer’s Disease Cooperative Study.
Intervention Participants were randomly assigned to algal DHA at a dose of 2 g/d or to identical placebo (60% were assigned to DHA and 40% were assigned to placebo). Duration of treatment was 18 months.
Main Outcome Measures Change in the cognitive subscale of the Alzheimer’s Disease Assessment Scale (ADAS-cog) and change in the Clinical Dementia Rating (CDR) sum of boxes. Rate of brain atrophy was also determined by volumetric magnetic resonance imaging in a subsample of participants (n = 102).
Results A total of 402 individuals were randomized and a total of 295 participants completed the trial while taking study medication (DHA: 171; placebo: 124). Supplementation with DHA had no beneficial effect on rate of change on ADAS-cog score, which increased by a mean of 7.98 points (95% confidence interval [CI], 6.51-9.45 points) for the DHA group during 18 months vs 8.27 points (95% CI, 6.72-9.82 points) for the placebo group (linear mixed-effects model: P = .41). The CDR sum of boxes score increased by 2.87 points (95% CI, 2.44-3.30 points) for the DHA group during 18 months compared with 2.93 points (95% CI, 2.44-3.42 points) for the placebo group (linear mixed-effects model: P = .68). In the subpopulation of participants (DHA: 53; placebo: 49), the rate of brain atrophy was not affected by treatment with DHA. Individuals in the DHA group had a mean decline in total brain volume of 24.7 cm3 (95% CI, 21.4-28.0 cm3) during 18 months and a 1.32% (95% CI, 1.14%-1.50%) volume decline per year compared with 24.0 cm3 (95% CI, 20-28 cm3) for the placebo group during 18 months and a 1.29% (95% CI, 1.07%-1.51%) volume decline per year (P = .79).
Conclusion Supplementation with DHA compared with placebo did not slow the rate of cognitive and functional decline in patients with mild to moderate Alzheimer disease.
Trial Registration clinicaltrials.gov Identifier: NCT00440050
