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Diet, Exercise and Dementia

Friday, October 29, 2010 // Uncategorized

8/17/2009 10:46:07 PM

Most people’s concept of The Mediterranean Diet is to substitute olive oil for butter.

This is a more detailed description of the concept.

“Mediterranean diet — There is no single Mediterranean diet, but such diets are typically high in fruits, vegetables, whole grains, beans, nuts, and seeds and include olive oil as an important source of fat. There are typically low to moderate amounts of fish, poultry, and dairy products, and there is little red meat.”

“Little red meat” means about two servings a month.

A recent study suggests that adhering to this type of diet along with exercise can reduce the risk of developing dementia.  Diet, alone, may not confer a benefit.  At least,according to the second study, if you’re French.  This is a summary of the studies from Journal Watch.

Mediterranean Diet, Physical Activity, and Risk for Dementia

Both diet and exercise are beneficial, but the combination seems particularly advantageous.

A Mediterranean diet (high intake of fruits, vegetables, and olive oil, and low intake of saturated fats, dairy products, and meats) is associated with lowered risks for cardiovascular disease and stroke and might also protect against cognitive decline. In two studies, researchers assessed this relation; in one, investigators also assessed the value of physical activity.

In an extension of the original prospective cohort study that showed a relation between a Mediterranean diet and lowered risk for Alzheimer disease (AD; Ann Neurol 2006; 59:912), diet and exercise were assessed in 1880 older New York City residents (mean age, 77). During mean follow-up of about 5 years, 282 participants developed AD. In adjusted analyses, both high physical activity and high adherence to a Mediterranean diet were associated with lower risk for developing AD. Absolute risk for developing AD was 19% in people with low physical activity and low diet adherence, compared with 12% in those who reported high levels of both behaviors.

In a prospective French cohort study that was designed to replicate the New York study, diet, cognitive function, and a wide range of clinical factors were assessed regularly in 1410 older adults (mean age, 76) during a mean follow-up of 5 years. No association was noted between degree of adherence to a Mediterranean diet and four standardized cognitive tests, except for a statistically significant but clinically modest effect on the Mini-Mental Status Examination (0.7 points during 5 years). No relation between diet and the incidence of dementia was observed in an analysis that was controlled for a wide range of clinical factors.

Comment: Although the protective benefit of physical activity on risk for AD seems clear in the New York study, the relation still should be studied in other populations. The benefit of a Mediterranean diet is less clear. Randomized trials that might prove that diet and exercise prevent cognitive decline are unlikely to be done. For now, clinicians can recommend both physical activity and the Mediterranean diet, particularly together, for preventing cardiovascular disease and stroke, with possible additional benefits for preventing cognitive decline and AD.

Thomas L. Schwenk, MD

Published in Journal Watch General Medicine August 13, 2009

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