Marine n-3 fatty acids and cognitive change among older adults in the VITAL randomized trial

Introduction : Few large, randomized trials have evaluated marine n-3 supplements and cognition in healthy older adults. Methods : Healthy community-dwelling participants aged 60+ years (mean [standard deviation] = 70.9 [5.8] years) in VITAL (randomized trial of n-3 fats [1 g/day, including 840 mg of eicosapentaenoic acid + docosahexaenoic acid] and vitamin D) were included: 3424 whose cognition was assessed by phone (VITAL-Cog; eight neuropsychological tests; 2.8 years) and 794 evaluated in person (CTSC-Cog; nine tests; 2.0 years). The primary outcome was a global score (average of test z-scores) of change over two assessments. We used multivariable-adjusted linear mixed models; substudy-specific results were meta-analyzed. Results : We observed no significant effect of n-3 supplementation: the mean difference in annual rate of cognitive change for the n-3 versus placebo group was -0.01 standard units (95% confidence interval [CI]: -0.02, 0.003) in VITAL-Cog and -0.002 (95% CI: -0.04, 0.03) in CTSC-Cog; the pooled difference was -0.01 (95% CI: -0.02, 0.003; P = .15). Discussion : Marine n-3 supplementation (1 g/day) did not confer cognitive benefits over 2 to 3 years in community-dwelling older adults.