November 23, 2009
Various studies suggest that a heart-healthy Mediterranean style diet, rich in fruits and vegetables and low in meat, may lower the risk of Alzheimer's disease. Regular physical activity has also been linked to a lower Alzheimer's risk. Now, a new study shows that both lifestyle measures together may be especially beneficial for brain health.
Researchers at Columbia University Medical Center in New York studied 1,880 elderly residents of New York City. None had dementia at the start of the study. All got standard brain and psychological tests about every year and a half. They also completed comprehensive questionnaires about the foods they ate.
The participants were sorted into groups according to how strongly they adhered to a Mediterranean-type diet, the kind traditionally eaten by natives of countries like Greece and Italy. Participants scored higher the more fruits, vegetables, legumes, cereals and fish they ate; the lower their consumption of meat and dairy products; and the higher their ratio of heart-healthy monounsaturated fats (like olive oil) to saturated fats (the kind found in red meats). Mild to moderate consumption of red wine is also considered part of the Mediterranean-style diet.
Participants were also graded according to their levels of physical activity. The most active elderly got about four hours of moderate activity, or 1.3 hours of vigorous activity, each week.
After an average of 5.4 years of follow up, 282 of the seniors had developed Alzheimer's disease.
The researchers found that seniors who were the most physically active had a lower risk for Alzheimer's. "Compared with physically inactive individuals, report of some physical activity was associated with a 29 percent to 41 percent lower risk of developing Alzheimer's disease, while report of much physical activity was associated with a 37 percent to 50 percent lower risk," the authors wrote.
A heart-healthy Mediterranean diet also appeared to lower the risk of developing Alzheimer's disease, independent of exercise levels. Belonging to the middle third of the diet group was associated with a 2 percent to 14 percent risk reduction, while belonging to the highest diet adherence group was associated with a 32 percent to 40 percent reduced risk.
But the greatest benefits occurred in those who both ate healthy and remained active. Participants who scored in the top one-third for both diet and exercise were 59 percent less likely to be diagnosed with Alzheimer's than those who scored in the lowest one-third.
"In summary, our results support the potentially independent and important role of both physical activity and dietary habits in relation to Alzheimer's disease risk," the authors wrote. "These findings should be further evaluated in other populations."
The Mediterranean diet may improve cholesterol levels, blood sugar levels and blood vessel health overall, or reduce inflammation, all of which have been associated with diminishing brain function. Exercise may have similar benefits for the blood vessels, including those that nourish the brain.
The main elements of the Mediterranean diet include:
*An abundance of plant foods, such as fruits, vegetables, cereals, nuts and beans.
*Using "good fats" like olive or canola oil, rather than butter or lard, and limiting dairy products like high-fat cheese and milk.
*Eating moderate amounts of fish and poultry, rather than red meat.
*Finally, drinking a glass or two of red wine a day.
Many other factors besides diet, including the genes you inherit and advancing age, play an important role in who ultimately develops Alzheimer's. Still, the findings add to a growing body of evidence that a heart-healthy lifestyle, with plenty of exercise, a sound diet, not smoking and keeping weight down, may help keep the brain young.
Nikolaos Scarmeas, MD; Jose A. Luchsinger, MD; Nicole Schupf, PhD; Adam M. Brickman, PhD; Stephanie Cosentino, PhD; Ming X. Tang, PhD; Yaakov Stern, PhD : "Physical Activity, Diet, and Risk of Alzheimer Disease." Journal of the American Medical Association, August 12, 2009; Volume 302 (number 6), pages 627-637.