Fish, docosahexaenoic acid and Alzheimer's disease

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Cognitive decline in the elderly, particularly Alzheimer's disease (AD), is a major socio-economic and healthcare concern. We review here the literature on one specific aspect of diet affecting AD, that of the ω3 fatty acids, particularly the brain’s principle ω3 fatty acid – docosahexaenoic acid (DHA). DHA has deservedly received wide attention as a nutrient supporting both optimal brain development and for cardiovascular health. Our aim here is to critically assess the quality of the present literature as well as the potential of ω3 fatty acids to treat or delay the onset of AD. We start with a brief description of cognitive decline in the elderly, followed by an overview of well recognized biological functions of DHA. We then turn to epidemiological studies, which are largely supportive of protective effects of fish and DHA against risk of AD. However, biological studies, including blood and brain DHA analyses need careful interpretation and further investigation, without which the success of clinical trials with DHA may continue to struggle. We draw attention to some of the methodological issues that need resolution as well as an emerging mechanism that may explain how DHA could be linked to protecting brain function in the elderly.

Keywords: Alzheimer’s disease; Docosahexaenoic acid; Fish; Aging; Brain; ω3 fatty acids; Eicosapentaenoic acid; Cognition; Dementia; Cognitive decline; Arachidonic acid

Abbreviations: Aβ, amyloid beta; AD, Alzheimer’s disease; ApoE, apolipoprotein E; ARA, arachidonic acid (20:4ω6); DHA, docosahexaenoic acid (22:6ω3); EPA, eicosapentaenoic acid (20:5ω3); GLUT1, glucose transporter 1; MCI, mild cognitive impairment; MMSE, mini mental state examination; NPD1, neuroprotectin D1; PE, phosphatidylethanolamine; PPAR, peroxisomal proliferator-activated receptor; PUFA, polyunsaturated fatty acid(s); RAR, retinoic acid receptor; RCT, randomized clinical trial; RXR, retinoid X receptor; TAG, triacylglycerol(s) or triglyceride(s)


Cunnane SC, Plourde M, Pifferi F, Bégin M, Féart C, Barberger-Gateau P. Fish, docosahexaenoic acid and Alzheimer’s disease. Progress in Lipid Research 2009;48(5): 239-256.

A copy of the full paper may be obtained from the publisher, a university library, or the corresponding author:
Stephen Cunnane, Department of Medicine and Research Center on Aging, 1036 Belvédère St. South, CSSS-IUGS, Université de Sherbrooke, Sherbrooke, QC, Canada J1H 4C4
Stephen.cunnane@usherbrooke.ca