Recent research indicates that n–3 fatty acids can inhibit cognitive decline,perhaps differentially by hypertensive status.

We tested these hypotheses in a prospective cohort study (the AtherosclerosisRisk in Communities). Dietary assessment using a food-frequencyquestionnaire and plasma fatty acid exposure by gas chromatography werecompleted in 1987–1989 (visit 1), while cognitive assessment withthree screening tools – the Delayed Word Recall Test, the DigitSymbol Substitution Test of the Wechsler Adult IntelligenceScale–Revised and the Word Fluency Test (WFT) – wascompleted in 1990–1992 (visit 2) and 1996–1998 (visit4). Regression calibration and simulation extrapolation were used to controlfor measurement error in dietary exposures.

Four US communities – Forsyth County (North Carolina), Jackson(Mississippi), suburbs of Minneapolis (Minnesota) and Washington County(Maryland).

Men and women aged 50–65 years at visit 1 with complete dietarydata (n = 7814); white men and women insame age group in the Minnesota field centre with complete plasma fatty aciddata (n = 2251).

Findings indicated that an increase of one standard deviation in dietarylong-chain n–3 fatty acids (%of energy intake) and balancing long-chain n−3/n–6 decreased the risk of 6-year cognitive decline inverbal fluency with an odds ratio (95% confidence interval) of 0.79(0.66–0.95) and 0.81 (0.68–0.96), respectively, amonghypertensives. An interaction with hypertensive status was found for dietarylong-chain n–3 fatty acids (gday−1) and WFT decline (likelihood ratio test,P = 0.06). This exposure in plasmacholesteryl esters was also protective against WFT decline, particularlyamong hypertensives (OR = 0.51, P< 0.05).

One implication from our study is that diets rich in fatty acids of marineorigin should be considered for middle-aged hypertensive subjects. To thisend, randomised clinical trials are needed.