Omega-3s and Brain Aging: A Connection?
Abstract and Commentary
By David Kiefer, MD
Synopsis: The researchers behind this study attempted to correlate quantitative measurements of omega-3 levels in red blood cells (RBC) with a variety of cognitive measures and tests for dementia. They found that people with lower RBC omega-3 levels had significantly worse results in brain testing.
Source: Tan ZS, et al. Red blood cell omega-3 fatty acid levels and markers of accelerated brain aging. Neurology 2012;78:658-664.
This new analysis of the well-known framingham co-hort (1575 community dwellers, aged 67 + 9 years, free of stroke and dementia) attempted to improve on prior studies showing mixed results for a connection between omega-3 intake (usually fatty fish) and dementia risk. By incorporating RBC fatty acid composition (with a lifespan of 120 days), rather than just dietary recall (known to be an inaccurate reflection of blood fatty acids) or plasma omega-3 levels (which only reflect a few days' intake), the researchers were hoping to more definitively assess this connection.
The participants in this study had blood drawn and analyzed for RBC fatty acid composition, and had a brain MRI (many measurements recorded) and neuropsychiatric (NP) testing approximately three months later. The three NP testing subsets that were a part of this study focused on cognitive domains that correlate with increased risk of Alzheimer's disease: the verbal memory component of the Logical Memory test, the visuospatial memory component of the Visual Reproductions test, and the Similarities test for abstract reasoning skills.
The RBC fatty acid testing yielded multiple fatty acid results, but the researchers focused on just the two that have been shown to correlate with the risk of dementia, RBC docosahexaenoic acid (DHA) and the omega-3 index (RBC DHA and eicosapentaenoic acid [EPA] expressed as a weight percentage of the total fatty acids).
When RBC DHA levels and omega-3 index were compared to the brain MRI findings, no linear correlation was seen. However, the lowest quartile of DHA levels and omega-3 index correlated with a lower total cerebral brain volume when compared to the upper three quartiles; the authors claim that this loss of brain volume correlates with an additional two years of brain aging. Other brain MRI findings were insignificant between the quartiles for both RBC DHA and omega-3 index.
Table 2. Sources of omega-3 fatty acids
- Cold water, fatty fish
- Cold-expeller-pressed canoloa oil
- Ground flaxseed
- Walnuts
- Unprocessed soy products
- Fortified eggs
With respect to NP testing, a positive association was seen between omega-3 index and RBC DHA levels on all tests except verbal memory. Some attenuation of the relationship between the omega-3 parameters and visual memory and executive function was seen when factoring in other know risk factors for dementia and cognitive decline.
Of note, given that this was a cross-sectional study, the authors point out that it was not possible to examine this cohort for the development of dementia, rather just look for connections between the omega-3 parameters and risk for dementia.
Commentary
This paper is an interesting addition to the literature exploring a connection between omega-3 status and brain health. The neurological effects of omega-3 fatty acids fit with the known high concentrations of phospholipids in the central nervous system; in particular, DHA is abundant in the brain. Recent research has demonstrated, in some but not all clinical trials, a relationship between maternal supplementation and childhood neurological development.1 One compelling and media-friendly result showed that increasing maternal DHA intake by 100 mg daily could lead to an improvement in a child's IQ of 0.13.2 In addition, low serum DHA levels may be associated with any number of neuropsychiatric disorders.3
On the other end of the human lifespan, some studies have shown that omega-3 supplementation may improve cognitive function, and that lower dietary intake of omega-3 fatty acids can lead to increased cognitive decline in the elderly. However, as hinted at above, there have been pitfalls in the dietary intake research. The study being reviewed here is an interesting approach to quantifying and improving on the omega-3 intake research and cognitive changes in a late-middle age cohort by measuring RBC omega-3 levels. RBCs don't cheat on dietary recall so this research approach should lead to more accurate results.
As much as the results of the study lend some hope to what might help prevent the development of dementia or, more generally, cognitive decline in this demographic, they remain preliminary and leave unanswered a few important questions. For example, why did some of the NP results correlate with RBC omega-3s, while other tests did not? How do the different RBC omega-3 levels relate to particular omega-3 intake (either dietary or supplementation), so as to make these results more clinically applicable? And, would these same results apply to non-Caucasian populations? Hopefully, follow-up research will address these questions and more in the process of refining our knowledge about omega-3s and the brain.
References
1. Isaacs EB, et al. 10-year cognition in preterms after random assignment to fatty acid supplementation in infancy. Pediatrics 2011;128:e890-898.
2. Cohen JT, et al. A quantitative analysis of prenatal intake of n-3 polyunsaturated fatty acids and cognitive development. Am J Prev Med 2005;29:366-374.
3. Schuchardt JP, et al. Significance of long-chain polyunsaturated fatty acids (PUFAs) for the development and behaviour of children. Eur J Pediatr 2010;169:149-164.
The researchers behind this study attempted to correlate quantitative measurements of omega-3 levels in red blood cells (RBC) with a variety of cognitive measures and tests for dementia. They found that people with lower RBC omega-3 levels had significantly worse results in brain testing.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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