fish & omega-3 oils
A study involving 266 people with mild cognitive impairment (aged 70+) has found that B vitamins are more effective in slowing cognitive decline when people have higher omega 3 levels.
Participants were randomly selected to receive either a B-vitamin supplement (folic acid, vitamins B6 and B12) or a placebo pill for two years. The vitamins had little to no effect for those with low levels of omega-3 fatty acids, but were very effective for those with high baseline omega-3 levels.
Levels of DHA appeared to be more important than levels of EPA, but more research is needed to confirm that.
The finding may help to explain why research looking at the effects of B vitamins, or the effects of omega-3 oils, have produced inconsistent findings.
The study followed research showing that B vitamins can slow or prevent brain atrophy and memory decline in people with MCI, and they were most effective in those who had above average blood levels of homocysteine.
 Oulhaj A, Jernerén F, Refsum H, A. Smith D, de Jager CA. Omega-3 Fatty Acid Status Enhances the Prevention of Cognitive Decline by B Vitamins in Mild Cognitive Impairment. Journal of Alzheimer's Disease [Internet]. 2016 ;50(2):547 - 557. Available from: http://www.medra.org/servlet/aliasResolver?alias=iospress&doi=10.3233/JAD-150777
I've spoken before about how the presence or absence of the “Alzheimer's gene” may affect which lifestyle changes are beneficial for you. A new study has added to that idea with a finding that seafood consumption was associated with fewer signs of Alzheimer's-related pathology, but only among those with the APOEe4 gene.
Seafood consumption was also associated with increased mercury levels in the brain, with levels rising the more seafood was consumed. However, higher levels of mercury were not correlated with any neuropathologies.
Fish oil supplementation was not associated with any differences in neuropathology. However, higher levels of alpha-linolenic acid (an omega-3 fatty acid found in flaxseed, chia seeds, walnuts, etc) were associated with a reduced chance of cerebral infarctions.
The study involved 554 deceased participants (average age 89.9 years) from the long-running Memory and Aging Project (MAP) conducted by Rush University Medical Center. The participants had completed annual dietary questionnaires over a number of years. The brains of 286 participants were autopsied, to assess neuropathologies and mercury levels.
The average educational attainment of the participants was 14.6 years; 67% were women.
The finding tempers the evidence from many studies that eating fish reduces Alzheimer's risk. However, it is consistent with what I believe is becoming apparent: that there are different paths to Alzheimer's, and thus different factors involved in preventing it, depending on your own particular gene-environment attributes.
 Morris M, Brockman J, Schneider JA, et al. ASsociation of seafood consumption, brain mercury level, and apoe ε4 status with brain neuropathology in older adults. JAMA [Internet]. 2016 ;315(5):489 - 497. Available from: http://dx.doi.org/10.1001/jama.2015.19451
Another study adds to the growing evidence that a Mediterranean diet is good for the aging brain.
The New York study used data from 674 non-demented older adults (average age 80). It found that those who closely followed such a diet showed significantly less brain shrinkage. Specifically, total brain volume was an average 13.11 milliliters greater, with grey matter volume 5 millilitres greater, and white matter 6.4 millilitres greater.
Eating at least five of the recommended Mediterranean diet components was associated with benefits equivalent to five years of age. By far the most important of these components was regular fish and reduced meat intake — at least 3 to 5 ounces of fish weekly; no more than 3.5 ounces of meat daily.
This is consistent with a considerable amount of research indicating the benefits of fish in fighting age-related cognitive decline.
 Gu Y, Brickman AM, Stern Y, Habeck CG, Razlighi QR, Luchsinger JA, Manly JJ, Schupf N, Mayeux R, Scarmeas N. Mediterranean diet and brain structure in a multiethnic elderly cohort. Neurology [Internet]. 2015 :10.1212/WNL.0000000000002121. Available from: http://www.neurology.org/content/early/2015/10/21/WNL.0000000000002121
A large, five-year study challenges the idea that omega-3 fatty acids can slow age-related cognitive decline. The study, involving 4,000 older adults, was part of the Age-Related Eye Disease Study (AREDS), which established that daily high doses of certain antioxidants and minerals can help slow the progression of age-related macular degeneration. However, a follow-up study found the addition of omega-3 fatty acids to the AREDS formula made no difference.
Omega-3 fatty acids are believed to be responsible for the health benefits associated with regularly eating fish, which is associated with lower rates of AMD, cardiovascular disease, and possibly dementia.
In this study, participants from the AREDS study, all of whom had early or intermediate AMD, were randomly assigned to either omega-3, or lutein and zeaxanthin (nutrients found in large amounts in green leafy vegetables), or both, or a placebo. As they all had AMD, participants also took the AREDS formula, which includes vitamins C, E, beta carotene, and zinc. Cognitive testing took place at the beginning, at 2 years, and at 4 years.
There was no benefit to these supplements: all groups showed a similar rate of cognitive decline over the study period.
The researchers speculate that the failure to find a benefit may lie in the age of the participants — it may be that supplements, to be of benefit, need to be started earlier. The other possibility (and the one I myself give greater weight to, although both factors may well be influential) is that these nutrients need to be taken in food to be effective.
It should be noted that the omega-3 fatty acids taken were those found in fish, not those found in plant foods such as flaxseed, walnuts, soy products, and canola and soybean oils.
 Chew EY, Clemons TE, Agrón E, et al. Effect of omega-3 fatty acids, lutein/zeaxanthin, or other nutrient supplementation on cognitive function: The areds2 randomized clinical trial. JAMA [Internet]. 2015 ;314(8):791 - 801. Available from: http://dx.doi.org/10.1001/jama.2015.9677
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