Plasma phosphatidylcholine docosahexaenoic acid content and risk of dementia and Alzheimer disease: the Framingham Heart Study.
Level 3 - non-randomized controlled study
Prospective observational cohort follow-up study
PubMed 17101822 · doi:10.1001/archneur.63.11.1545
What was done
A prospective cohort study of 899 men and women free of dementia at baseline (median age 76.0 years) from the Framingham Heart Study followed for a mean of 9.1 years. Baseline plasma phosphatidylcholine (PC) fatty acid levels were measured. Cox proportional regression was used to calculate relative risks of all-cause dementia and Alzheimer disease comparing participants in the highest quartile of PC DHA to the lower three quartiles, adjusting for age, sex, apolipoprotein E epsilon4 allele, plasma homocysteine concentration, and education level. Dietary intake was assessed in a subset of 488 participants.
What was found
During follow-up, 99 incident dementia cases occurred, including 71 Alzheimer disease cases. After multivariable adjustment, subjects in the upper quartile of baseline plasma PC DHA had a relative risk of 0.53 for all-cause dementia (95% CI, 0.29–0.97; P = .04) and 0.61 for Alzheimer disease (95% CI, 0.31–1.18; P = .14) compared with the lower three quartiles. In the subset of 488 participants, the top quartile corresponded to a mean DHA intake of 0.18 g/d and a mean fish intake of 3.0 servings per week (P < .001). No other significant associations were observed.
Why it matters
This study provides prospective observational evidence linking higher circulating DHA concentrations, associated with higher dietary fish intake, to a lower risk of developing all-cause dementia in older adults.
Limits
The observational design cannot establish causality. Fatty acid levels were measured only at baseline without capturing longitudinal dietary changes. Total incident dementia events were modest (99 cases), the reduction in Alzheimer disease risk was not statistically significant, and dietary data were available only for a subset of 488 participants.
Cited by
- partial An omega-3 index in the 8% range is associated with a 66% lower risk of dementia.