Serum omega-3 fatty acids and cognitive domains in community-dwelling older adults from the NuAge Study: Exploring the associations with other fatty acids and sex

Background: Omega-3 (n-3) polyunsaturated fatty acids (PUFAs) are suggested to play a role in the prevention of cognitive decline. The evidence may be inconsistent due to methodological issues including interrelations with other long-chain (14 or more carbons) fatty acids (LCFAs) and use of sex as a confounding factor rather than an effect modifier.

Objective: This study evaluated the association between serum n-3 PUFAs and performance across four cognitive domains, overall and by sex, while controlling for other LCFAs.

Methods: 386 healthy older adults (77.4 ± 3.8 years; 53% females) from the Québec Longitudinal Study on Nutrition and Successful Aging underwent a cognitive evaluation and blood sampling. Verbal and non-verbal episodic memory, executive functioning, and processing speed were evaluated. Serum LCFA concentrations were measured by gas chromatography. LCFAs were grouped according to standard fatty acid classes and according to a factor analysis using principal component analysis (FA-PCA). Multivariate linear regression models were performed, including unadjusted and adjusted models for other LCFAs.

Results: Higher n-3 PUFA concentrations were associated with better non-verbal memory and processing speed in fully adjusted models not including other LCFAs (betas of 0.21 and 0.19, respectively). The magnitude of these associations varied when other LCFAs were entered in the model (betas of 0.27 and 0.32, respectively) or when FA-PCA factors were considered (betas of 0.27 and 0.21, respectively). Associations with verbal episodic memory were limited to higher concentrations of eicosapentaenoic acid whereas there was no association between n-3 PUFAs and executive functioning. Higher n-3 PUFAs were associated with better verbal and non-verbal episodic memory in females, and with better executive functioning and processing speed in males.

Conclusions: These results suggest that other LCFAs should be considered when evaluating the association between n-3 PUFAs and cognitive performance in healthy older adults. Sex differences across cognitive domains warrant further investigation.