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Original Contribution
October 2006

ω-3 Fatty Acid Treatment in 174 Patients With Mild to Moderate Alzheimer Disease: OmegAD Study: A Randomized Double-blind Trial

Author Affiliations

Author Affiliations: Department of Neurobiology, Caring Sciences and Society, Section of Clinical Geriatrics (Drs Freund-Levi, Eriksdotter-Jönhagen, Faxén-Irving, Garlind, and Wahlund), Department of Medicine, Division of Hematology (Ms Vedin and Dr Palmblad), Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm; and Department of Public Health and Caring Sciences, Clinical Nutrition and Metabolism (Drs Cederholm and Vessby), and Division of Geriatrics, Uppsala University Hospital, Uppsala (Dr Basun), Sweden.

Arch Neurol. 2006;63(10):1402-1408. doi:10.1001/archneur.63.10.1402

Background  Epidemiologic and animal studies have suggested that dietary fish or fish oil rich in ω-3 fatty acids, for example, docosahexaenoic acid and eicosapentaenoic acid, may prevent Alzheimer disease (AD).

Objective  To determine effects of dietary ω-3 fatty acid supplementation on cognitive functions in patients with mild to moderate AD.

Design  Randomized, double-blind, placebo-controlled clinical trial.

Participants  Two hundred four patients with AD (age range [mean ± SD], 74 ± 9 years) whose conditions were stable while receiving acetylcholine esterase inhibitor treatment and who had a Mini-Mental State Examination (MMSE) score of 15 points or more were randomized to daily intake of 1.7 g of docosahexaenoic acid and 0.6 g of eicosapentaenoic acid (ω-3 fatty acid–treated group) or placebo for 6 months, after which all received ω-3 fatty acid supplementation for 6 months more.

Main Outcome Measures  The primary outcome was cognition measured with the MMSE and the cognitive portion of the Alzheimer Disease Assessment Scale. The secondary outcome was global function as assessed with the Clinical Dementia Rating Scale; safety and tolerability of ω-3 fatty acid supplementation; and blood pressure determinations.

Results  One hundred seventy-four patients fulfilled the trial. At baseline, mean values for the Clinical Dementia Rating Scale, MMSE, and cognitive portion of the Alzheimer Disease Assessment Scale in the 2 randomized groups were similar. At 6 months, the decline in cognitive functions as assessed by the latter 2 scales did not differ between the groups. However, in a subgroup (n = 32) with very mild cognitive dysfunction (MMSE >27 points), a significant (P<.05) reduction in MMSE decline rate was observed in the ω-3 fatty acid–treated group compared with the placebo group. A similar arrest in decline rate was observed between 6 and 12 months in this placebo subgroup when receiving ω-3 fatty acid supplementation. The ω-3 fatty acid treatment was safe and well tolerated.

Conclusions  Administration of ω-3 fatty acid in patients with mild to moderate AD did not delay the rate of cognitive decline according to the MMSE or the cognitive portion of the Alzheimer Disease Assessment Scale. However, positive effects were observed in a small group of patients with very mild AD (MMSE >27 points).

Trial Registration  clinicaltrials.gov Identifier: NCT00211159