Submitted to: Archives of Neurology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2006
Publication Date: 11/1/2006
Citation: Schaefer, E., Bongard, V., Beiser, A.S., Tucker, K., Kyle, D.J., Wilson, P.W., Wolf, P.A. 2006. Plasma phosphatidylcholine docosahexaenoic acid content and risk of dementia and Alzheimer disease: the Framingham Heart Study. Archives of Neurology. 63(11):1545-1550.
Interpretive Summary: Docosahexaenoic acid (DHA) is a fatty acid that is abundant in fish. It may play a major role in brain cell functioning. Our hypothesis in carrying out this analysis, was that DHA may protect against the development of dementia and Alzheimer's disease. During a mean period of 9 years, we followed a cohort of 899 participants in the Framingham Heart study (mean age 75.4 and 76.3 years for men and women respectively). At the beginning of the follow-up, each subject was free of dementia. A blood sample was taken to measure blood level of DHA, and a dietary questionnaire was filled in by the participants to estimate their average fish consumption. Ninety nine cases of dementia (71 of Alzheimer's disease) occurred during the follow-up. After taking into account the effect of potential confounding factors, subjects with the highest blood level of DHA (upper quartile) experienced a 47% reduction in the occurrence of dementia as compared with subjects with lower blood levels of DHA. Consuming more than two servings of fish per week was associated with a 59% reduction in the occurrence of Alzheimer's disease. High blood DHA and high fish consumption may protect against the risk of dementia and Alzheimer's disease.
Technical Abstract: Our aim in carrying out this analysis, was to assess the predictive value of plasma phosphatidylcholine (PC) DHA content, DHA intake, and fish intake for the risk of developing dementia in the Framingham Heart Study. A cohort of 899 subjects free of dementia was followed to assess the onset of incident dementia (mean follow-up: 9 years). At baseline, plasma PC DHA was measured and dietary DHA and fish intakes were assessed. The mean age of men and women at baseline was 75.4 years (standard deviation: 4.9) and 76.3 (5.3). Ninety nine new cases of dementia (71 of Alzheimer's disease) occurred during the follow-up. Subjects in the highest plasma PC DHA quartile had the highest DHA and fish consumptions (p<0.0001). After adjustment for age, sex, and apolipoprotein e4 allele, the relative risk of dementia was 0.53 (p=0.031) in the upper plasma PC DHA quartile as compared with the lower three quartiles. Consuming more than two servings of fish per week (which corresponded to more than 0.15 g/day of DHA) was associated with adjusted relative risks of dementia and Alzheimer's disease of 0.51 (p=0.078) and 0.41 (p=0.049) respectively. Increased plasma phosphatidylcholine DHA was associated with a significant 47% reduction in the risk of dementia, while a fish consumption higher than two servings per week was associated with a significant 59% reduction in the risk of Alzheimer's disease.