Background: Very-long-chain n–3 polyunsaturated fatty acids (n–3 PUFAs) are suggested to be related to cognitive performance in older adults. However, limited data exist on the association between n–3 PUFAs and performance in specific cognitive domains.
Objective: We evaluated the association between plasma n–3 PUFA proportions and cognitive performance in 5 cognitive domains and determined whether plasma n–3 PUFA proportions predict cognitive change over 3 y.
Design: We used data from the FACIT trial, in which participants received folic acid or placebo capsules for 3 y. Fatty acid proportions in plasma cholesteryl esters at baseline were measured in 807 men and women aged 50–70 y. Cognitive performance for memory, sensorimotor speed, complex speed, information-processing speed, and word fluency was assessed at baseline and after 3 y. The cross-sectional analyses were based on all 807 participants; the longitudinal analyses were based only on 404 participants in the placebo group.
Results: Higher plasma n–3 PUFA proportions predicted less decline in sensorimotor speed (multiple linear regression coefficient, z score = 0.31; 95% CI: 0.06, 0.57) and complex speed (0.40; 95% CI: 0.10, 0.70) over 3 y. Plasma n–3 PUFA proportions did not predict 3-y changes in memory, information-processing speed, or word fluency. The cross-sectional analyses showed no association between plasma n–3 PUFA proportions and performance in any of the 5 cognitive domains.
Conclusions: In this population, plasma n–3 PUFA proportions were associated with less decline in the speed-related cognitive domains over 3 y. These results need to be confirmed in randomized controlled trials.