Elderly individuals who had a diet that included higher consumption of fruits, vegetables, legumes, cereal and fish and was low in red meat and poultry and who were physically active had an associated lower risk of Alzheimer disease, according to a study in the August 12 issue of JAMA. In a second study, higher adherence to a Mediterranean diet was associated with slower cognitive decline, but was not associated with a decreased risk of dementia.
Research regarding the effect physical activity can have on the risk of Alzheimer disease (AD) or dementia has shown mixed results, as has the effect of dietary habits. Their combined association has not been investigated, according to background information in the article.
Nikolaos Scarmeas, M.D., of Columbia University Medical Center, New York, and colleagues examined the association between physical activity and risk of AD and also the effect of physical activity and adherence to a Mediterranean-type diet on AD risk. The study included 2 groups that consisted of 1,880 community-dwelling elderly residents of New York city without dementia at the start of the study, for whom there was both diet and physical activity information available. Standardized neurological and neuropsychological measures were administered approximately every 1.5 years from 1992 through 2006.
Smarter and better educated people have a lower incidence of Alzheimer's. I always wonder about diet studies and Alzheimer's risk reduction since smart people are more likely to eat fish, vegetables, and fruits and otherwise eat a diet that matches up with best practice. So what's the direction of cause and effect? I suspect most of the difference is due to diet and exercise since we have plenty of other indicators that diet makes a difference in cardiovascular health and brain health.
The risk reduction found is substantial.
The authors also write, "Compared with individuals with low physical activity plus low adherence to a diet (absolute AD risk, 19 percent), high physical activity plus high diet adherence was associated with a 35 percent to 44 percent relative risk reduction (absolute AD risk, 12 percent). … Absolute AD risks declined from 21 percent in the group with no physical activity plus low diet adherence to 9 percent in the group with much physical activity plus high diet adherence."
I'd like to know whether meat is associated with a worse outcome because of properties of meat or because meat displaces fish in diet. Is it bad stuff in meat or good stuff in fish that makes the difference?
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