Executive functions and the ω-6-to-ω-3 fatty acid ratio: a cross-sectional study

Abstract

Background: The ω-6 (n-6) to ω-3 (n-3) fatty acid (FA) ratio (n-6:n-3 ratio) was previously shown to be a predictor of executive function performance in children aged 7-9 y.

Objective: We aimed to replicate and extend previous findings by exploring the role of the n-6:n-3 ratio in executive function performance. We hypothesized that there would be an interaction between n-3 and the n-6:n-3 ratio, with children with low n-3 performing best with a low ratio, and those with high n-3 performing best with a high ratio.

Design: Children were recruited on the basis of their consumption of n-6 and n-3 FAs. The executive function performance of 78 children aged 7-12 y was tested with the use of the Cambridge Neuropsychological Test Automated Battery and a planning task. Participants provided blood for plasma FA quantification, and the caregiver completed demographic and activity questionnaires. We investigated the role of the n-6:n-3 ratio in the entire sample and separately in children aged 7-9 y (n = 41) and 10-12 y (n = 37).

Results: Dietary and plasma n-6:n-3 ratio and n-3 predicted performance on working memory and planning tasks in children 7-12 y old. The interaction between dietary n-6:n-3 ratio and n-3 predicted the number of moves required to solve the most difficult planning problems in children aged 7-9 y and those aged 10-12 y, similar to results from the previous study. There was also an interaction between the plasma n-6:n-3 ratio and n-3 predicting time spent thinking through the difficult 5-move planning problems. The n-6:n-3 ratio and n-3 predicted executive function performance differently in children aged 7-9 y and in those aged 10-12 y, indicating different optimal FA balances across development.

Conclusions: The n-6:n-3 ratio is an important consideration in the role of FAs in cognitive function, and the optimal balance of n-6 and n-3 FAs depends on the cognitive function and developmental period studied. This trial was registered at clinicaltrials.gov as NCT02199808.

Keywords: CANTAB; Electric Maze Task; executive functions; fatty acids; middle childhood.

© 2017 American Society for Nutrition.

Figures

FIGURE 1

Flowchart of participant recruitment, screening, and inclusion in the laboratory visit and analyses.

FIGURE 2

Electric Maze Task. Basic set-up, including 6 × 8 mat, the control box, and marked starting and ending squares (A). Modified dimensional change card sort task with red and yellow stars and circles and marked starting and ending squares (B).

FIGURE 3

Interaction between dietary n–6:n–3 ratio and n–3 predicting mean moves required to solve the 5-move Stockings of Cambridge planning problems in children aged 7–9 y. There was a significant main effect of ratio group [F(9, 27) = 3.68; P < 0.05] and a ratio group by n–3 group interaction [F(3, 27) = 2.98; P < 0.05], but no main effect of n–3 group [F(3, 27) = 2.63; P > 0.05]. *Significant differences between the low ratio, low n–3 group (n = 2) and both the high ratio, low n–3 group (n = 7) and mean ratio, low n–3 group (n = 4). There were no significant differences between any other groups (high ratio, high n–3, n = 2; high ratio, mean n–3, n = 6; mean ratio, high n–3, n = 7; mean ratio, mean n–3, n = 6; low ratio, high n–3, n = 5; and low ratio, mean n–3, n = 2).

FIGURE 4

ANOVA results of interaction between dietary n–6:n–3 ratio and n–3 predicting mean moves required to solve the 5-move Stockings of Cambridge planning problems in children aged 10–12 y. There was a significant interaction between ratio group and n–3 intake group [F(9, 20) = 3.66; P < 0.05], but no main effect of ratio group [F(3, 20) = 3.23; P > 0.05] or n–3 intake group [F(3, 20) = 0.4; P > 0.05]. *Significant difference (Tukey’s post hoc analysis) between the high ratio, high n–3 group (n = 3) and the low ratio, high n–3 group (n = 7). There were no significant differences between any other groups (high ratio, mean n–3, n = 6; high ratio, low n–3, n = 8; mean ratio, high n–3, n = 2; mean ratio, mean n–3, n = 2; mean ratio, low n–3, n = 2; low ratio, mean n–3, n = 2; and low ratio, low n–3, n = 2).

FIGURE 5

Simple slope graph of the interaction between the n–6:n–3 ratio and plasma n–3 predicting mean subsequent thinking time on the 5-move Stockings of Cambridge problems for the entire sample. The slopes for low plasma n–3 (1 SD below the mean, n = 3, T = 4.38, P < 0.05) and mean plasma n–3 (n = 21, T = 2.49, P < 0.05) were significant, and both groups solved planning problems more quickly with lower n–6:n–3 ratios. The slope for high plasma n–3 was not significant (n = 3, T = −0.25, P > 0.05), indicating no difference across n–6:n–3 ratios. The main effect of the plasma n–6:n–3 ratio [T (27) = 3.62; P < 0.05], the main effect of plasma n–3 [T (27) = 2.85; P < 0.05], and their interaction [T (27) = −2.66; P < 0.05] were all significant. Data for the simple slope analysis were obtained from the covariance matrix generated from the regression model.