Plasma and Brain Fatty Acid Profiles in Mild Cognitive Impairment and Alzheimer's Disease

Article type: Research Article

Authors: Cunnane, Stephen C.^{a; *} | Schneider, Julie A.^{b; c; d} | Tangney, Christine^e | Tremblay-Mercier, Jennifer^a | Fortier, Mélanie^a | Bennett, David A.^{b; c} | Morris, Martha Clare^f

Affiliations: [a] Research Center on Aging and Department of Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada | [b] Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, IL, USA | [c] Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA | [d] Department of Pathology, Rush University Medical Center, Chicago, IL, USA | [e] Department of Clinical Nutrition, Rush University Medical Center, Chicago, IL, USA | [f] Internal Medicine Section on Nutrition and Nutritional Epidemiology, Rush University Medical Center, Chicago, IL, USA

Correspondence: [*] Correspondence to: Stephen C. Cunnane, Research Center on Aging, 1036 Belvedere St. South, Sherbrooke, J1H 4C4, QC, Canada. Tel.: +1 819 780 2220 (Ext 45670); Fax: +1 819 829 7141; E-mail: [email protected].

Abstract: Alzheimer's disease (AD) is generally associated with lower omega-3 fatty acid intake from fish but despite numerous studies, it is still unclear whether there are differences in omega-3 fatty acids in plasma or brain. In matched plasma and brain samples provided by the Memory and Aging Project, fatty acid profiles were quantified in several plasma lipid classes and in three brain cortical regions. Fatty acid data were expressed as % composition and as concentrations (mg/dL for plasma or mg/g for brain). Differences in plasma fatty acid profiles between AD, mild cognitive impairment (MCI), and those with no cognitive impairment (NCI) were most apparent in the plasma free fatty acids (lower oleic acid isomers and omega-6 fatty acids in AD) and phospholipids (lower omega-3 fatty acids in AD). In brain, % DHA was lower only in phosphatidylserine of mid-frontal cortex and superior temporal cortex in AD compared to NCI (−14% and −12%, respectively; both p < 0.05). The only significant correlation between plasma and brain fatty acids was between % DHA in plasma total lipids and % DHA in phosphatidylethanolamine of the angular gyrus, but only in the NCI group (+0.77, p < 0.05). We conclude that AD is associated with altered plasma status of both DHA and other fatty acids unrelated to DHA, and that the lipid class-dependent nature of these differences reflects a combination of differences in intake and metabolism.

Keywords: Alzheimer's disease, brain lipids, docosahexaenoic acid, free fatty acids, mild cognitive impairment, memory and aging project, oleic acid, omega-3 fatty acids, polyunsaturates, phospholipids

DOI: 10.3233/JAD-2012-110629

Journal: Journal of Alzheimer's Disease, vol. 29, no. 3, pp. 691-697, 2012