Cognitive changes with omega-3 polyunsaturated fatty acids in non-demented older adults with low omega-3 index

OBJECTIVES: To investigate the changes in specific domains of cognitive function in older adults reporting subjective memory complaints with a low omega-3 index receiving omega 3 polyunsaturated fatty acid (n-3 PUFA) supplementation or placebo. DESIGN: This is a secondary exploratory analysis of the Multidomain Alzheimer Preventive Trial (MAPT) using subjects randomized to the n-3 PUFA supplementation or placebo group. SETTING: French community dwellers aged 70 or over reporting subjective memory complaints, but free from clinical dementia. PARTICIPANTS: A subgroup of MAPT subjects in the lowest quartile of omega-3 index distribution with baseline values ≤ 4.83 % (n = 183). INTERVENTION: The n-3 PUFA supplementation group consumed a daily dose of DHA (800 mg) and EPA (a maximum amount of 225 mg) for 3 years. The placebo group received identical capsules comprising liquid paraffin oil. MEASUREMENTS: Linear mixed-model repeated-measures analyses were used including baseline, 6, 12, 24 and 36-month follow-up data to assess between-group differences in the change in eight cognitive tests over 36 months. RESULTS: There was less decline on the Controlled Oral Word Association Test (COWAT) in the n-3 PUFA supplementation group compared to placebo (p = 0.009; between group mean difference over 36 months, 2.3; 95% CI, 0.6,4.0). No significant differences for any of the other cognitive tests were found, including other tests of executive functioning, although, numerically all results were in favour of the n-3 PUFA supplementation. CONCLUSIONS: We found some evidence that n-3 PUFAs might be beneficial for the maintenance of executive functioning in older adults at risk of dementia with low omega-3 index, but this exploratory finding requires further confirmation. A larger specifically designed randomised controlled trial could be merited.