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Original Contribution
November 2006

Plasma Phosphatidylcholine Docosahexaenoic Acid Content and Risk of Dementia and Alzheimer Disease: The Framingham Heart Study

Author Affiliations

Author Affiliations: Lipid Metabolism Laboratory (Drs Schaefer, Bongard, and Lamon-Fava) and Dietary Assessment and Epidemiology Program (Dr Tucker), Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Department of Biostatistics, Boston University School of Public Health (Dr Beiser), and Department of Endocrinology, Nutrition, and Diabetes (Dr Robins) and Department of Neurology (Drs Au and Wolf), Boston University School of Medicine, Boston, Mass; Martek Biosciences Corporation, Columbia, Md (Dr Kyle); and Framingham Heart Study, National Heart, Lung, and Blood Institute, Framingham, Mass (Drs Wilson and Wolf).

Arch Neurol. 2006;63(11):1545-1550. doi:10.1001/archneur.63.11.1545

Background  Docosahexaenoic acid (DHA) is an abundant fatty acid in the brain. In the diet, DHA is found mostly in fatty fish. The content of DHA has been shown to be decreased in the brain and plasma of patients with dementia.

Objective  To determine whether plasma phosphatidylcholine (PC) DHA content is associated with the risk of developing dementia.

Design, Setting, and Participants  A prospective follow-up study in 899 men and women who were free of dementia at baseline, had a median age of 76.0 years, and were followed up for a mean of 9.1 years for the development of all-cause dementia and Alzheimer disease.

Main Outcome Measures  Plasma PC fatty acid levels were measured at baseline. Cox proportional regression analysis was used to assess relative risks of all-cause dementia and Alzheimer disease according to baseline plasma levels.

Results  Ninety-nine new cases of dementia (including 71 of Alzheimer disease) occurred during the follow-up. After adjustment for age, sex, apolipoprotein E ε4 allele, plasma homocysteine concentration, and education level, subjects in the upper quartile of baseline plasma PC DHA levels, compared with subjects in the lower 3 quartiles, had a relative risk of 0.53 of developing all-cause dementia (95% confidence interval, 0.29-0.97; P=.04) and 0.61 of developing Alzheimer disease (95% confidence interval, 0.31-1.18; P=.14). Subjects in the upper quartile of plasma PC DHA levels had a mean DHA intake of 0.18 g/d and a mean fish intake of 3.0 servings per week (P<.001) in a subset of 488 participants. We found no other significant associations.

Conclusion  The top quartile of plasma PC DHA level was associated with a significant 47% reduction in the risk of developing all-cause dementia in the Framingham Heart Study.