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Abstract
This was a sub-analysis of the AREDS2 research trial, a cohort of 3501 people out of the total 4203 AREDS2 participants. A total of 2461 people underwent composite cognition statistical analyses to determine the primary outcome variable, the effect of n-3 supplementation on cognition. The authors found that 1 g of supplemental EPA + DHA added to a vitamin supplement for age-related macular degeneration did not prevent cognitive decline.
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Background: Omega-3 polyunsaturated fatty acids (n-3 PUFAs) are promoted as cognitive enhancers with consumption recommended in the general population and those with neurocognitive deficits such as attention deficit hyperactivity disorder (ADHD). However, evidence from randomised placebo-controlled trials is inconclusive.
Aims: This study aimed to conduct a systematic review and meta-analysis examining the effect of n-3 PUFA supplementation on cognition in healthy populations and those with ADHD and related disorders (RDs).
Methods: Databases were searched for randomised controlled trials (RCTs) in adults and school-aged children (who were healthy and typically developing (TD) or had ADHD or a related-neurodevelopmental disorder (ADHD+RD)) which assessed the effects of n-3 PUFA on cognition.
Results: In the 24 included studies n-3 PUFA supplementation, in the whole sample and the TD and ADHD+RD subgroup, did not show improvements in any of the cognitive performance measures. In those with low n-3 PUFA status, supplementation improved short-term memory.
Conclusions: There is marginal evidence that n-3 PUFA supplementation effects cognition in those who are n-3 PUFA deficient. However, there is no evidence of an effect in the general population or those with neurodevelopmental disorders. This has important implications given the widespread advertisement and consumption of n-3 PUFA; claims of cognitive benefit should be narrowed.
Loss of cognitive function and the development of dementia are among the greatest concerns confronting older individuals. As populations around the world age, the global prevalence of dementia is predicted to increase substantially from an estimated 35.6 million in 2010 to 65.7 million in 2030, and 115.4 million in 2050.1 In the United States in 1990, Alzheimer disease ranked 25th in terms of disability-adjusted life-years lost. In 2010, it ranked 12th, with the greatest median percentage change of any of the leading 30 diseases.2 The burden of mild cognitive impairment (MCI) is even larger.3 Discussions between physicians and patients about strategies to prevent cognitive decline and dementia have become commonplace, and there is great interest in new evidence of lifestyle modifications that might improve cognitive aging and prevent the onset of dementia. These lifestyle modifications include exercise, dietary changes, cognitive training (ie, “brain games”), and multimodal treatments. A meta-analysis of observational studies found that the modifiable risk factors that have most consistently been associated with a reduced risk of dementia include higher educational attainment, increased physical activity, and avoidance of smoking.4
In vegetarian population, vitamin B12 deficiency coexists with suboptimal levels of omega-3 fatty acids. Studies indicate a need for supplementation/fortification of vitamin B12 and omega-3 fatty acids to reduce the risk of brain disorders. We have described the effects of vitamin B12 and omega-3 fatty acid supplementation on brain development in F1 generation animals. The current study investigates the effects of vitamin B12 and omega-3 fatty acids supplementation on brain function and cognition. Pregnant Wistar rats were assigned the following groups: control, vitamin B12 deficient (BD), vitamin B12 deficient + omega-3 fatty acid (BDO), vitamin B12 supplemented (BS), vitamin B12 supplemented + omega-3 fatty acid (BSO). The same diets were continued for two generations. BDO group showed higher (P < 0.05) levels of BDNF (brain derived neurotrophic factor) and DHA (docosahexaenoic acid) in the cortex and hippocampus as compared with the BD group. The cognitive performance was also normalized in this group. BS showed comparable levels of DHA, BDNF (protein and mRNA), and CREB mRNA (cAMP response element-binding protein) to that of control group while Tropomyosin receptor kinase mRNA levels were higher. The combined vitamin B12 and omega-3 fatty acid supplementation further enhanced the levels of DHA (P < 0.05) and BDNF (P < 0.05) in the hippocampus and CREB mRNA (P < 0.01) in the cortex as compared with BS group. The cognitive performance of these animals was higher (P < 0.05) as compared with BS group. Our data indicates the beneficial effects of vitamin B12 and omega-3 fatty acid supplementation across two generations on brain development and function. © 2015 BioFactors, 2015.
© 2015 International Union of Biochemistry and Molecular Biology.
Numerous longitudinal observational studies have suggested that nutrients, such as antioxidants, B vitamins, and ω-3 fatty acids, may prevent cognitive decline or dementia. There is very little evidence from well-sized randomized controlled trials that nutritional interventions can benefit cognition in later life. Nutritional interventions may be more effective in individuals with poorer nutritional status or as part of multidomain interventions simultaneously targeting multiple lifestyle factors. Further evidence, notably from randomized controlled trials, is required to prove or refute these hypotheses.
Copyright © 2015 Elsevier Inc. All rights reserved.