Team McCallum

R&D for Lifetime of Life

Omega-3 slows Alzheimer’s?

Dr Jospeph F Quinn reported in the Journal of the American Medical Association on findings from a study of 300 adults with mild to moderate Alzheimer’s and the impact of one omega-3 component, DHA, on progression of the disease. The research team concluded “Supplementation with DHA compared with placebo did not slow the rate of cognitive and functional decline in patients with mild to moderate Alzheimer disease.”

This is the angle the media appears to be running with, but the full story is somewhat different. Those people with the APOE4 genetic variation associated with inherited Alzheimer’s got no benefit. Those without appeared to gain some benefit from the DHA.

Omega-3 comes in 3 forms. ALA is common in plant sources and humans can convert this to the other 2 forms, but only inefficiently. So we need to get the other two forms EPA and DHA from food, and the main source is oily fish (or supplements).

Prior studies have shown the following. EPA is virtually absent from the brain. DHA is present in large quantities, necessary for brain function and is seen in depleted levels in people with Alzheimer’s.  Six studies have shown that consumption of fish is associated with a reduced risk of cognitve decline and dementia.  Animal studies have shown that DHA supplementation is associated with less amyloid-beta plaques and other damage. Further, the studies are at levels of supplementation which take DHA well above the average found in the US population. Hence the focus on DHA.

The dose used here provided approximately one gram of DHA per day, and blood tests showed it pushed up DHA blood levels significantly.

A battery of tests was administered over the 18 month trial period.

When considering the DHA group as a whole, it appeared to have minor benefits over the placebo group, but so small as to not be clinically significant, hence the authors’ conclusion. 

However, when considering only those without the ‘bad’ APOE4 variation, some of the tests showed better results for the DHA group, while others were not statistically significant. Three other studies have also found that omega-3 works, but only for the non-APOE4 people.

One further point raised by the study authors is that research has shown that DHA works better if administered together with an anti-oxidant (as otherwise the DHA can be oxidised).  Dr Quinn’s study used DHA without an anti-oxidant so the full story has yet to be told.

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November 2, 2010 - Posted by | Alzheimer's, APOE, Omega-3, Success

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