= Full article availableScientists are taking a closer look at the connections between what you eat and your risk of Alzheimer’s disease and cognitive decline. In a recently published Columbia University study, researchers found an association between reduced Alzheimer’s risk and a dietary pattern similar to the so-called “Mediterranean diet.” And several related dietary factors were in the spotlight in May at the International Academy of Nutrition and Aging’s (IANA) conference on nutrition, Alzheimer’s disease and cognitive decline.
The new study, published in Annals of Neurology, followed 2,258 elderly northern Manhattanites over an average of four years. Every 18 months, they were evaluated with a dozen neuropsychological tests and given a food questionnaire. Over the span of the study, 262 participants were diagnosed as developing Alzheimer’s disease.
Researchers used a nine-point scale to measure subjects’ adherence to elements of a Mediterranean-style diet. Although there’s no single true “Mediterranean diet”—people in Tunisia eat differently from those in, say, Greece—certain common components of the region’s diet have previously been linked to a reduced risk of cardiovascular disease. (See the November 2004 Healthletter.) In the Columbia study, scientists looked for:
- High intake of vegetables, legumes, fruits, fish and cereals
- High intake of unsaturated fatty acids but low intake of saturated lipids
- Low intake of dairy products, meat and poultry
- Mild to moderate alcohol consumption
Even after adjusting for demographics and known risk factors, adherence to the Mediterranean-style dietary pattern remained the main predictor of Alzheimer’s risk. Each additional unit of adherence to the diet was associated with a 9–10% reduced risk. The one-third of the subjects who followed the diet most closely had a 39-40% lower risk of Alzheimer’s than the group with the lowest adherence.
Presentations at the special IANA symposium in Chicago mirrored many of the nutritional elements in the study. Co-sponsored by Rush University’s Institute for Healthy Aging, the conference looked at the possible protective benefits of B vitamins and polyphenols—both found in fruits and vegetables—as well as polyunsaturated fatty acids, especially the omega-3s found in certain fish.
But another possible lesson of the Columbia research is that it’s not just individual nutrients that may offer protection from cognitive decline—it’s the whole dietary pattern. Although mild to moderate alcohol intake and high vegetable consumption were each associated with decreased risk, after further adjustment for other factors, no individual component proved a significant risk predictor. According to lead researcher Nikolaos Scarmeas, MD, “An overall dietary pattern is likely to have a greater effect on human health than a single nutrient.”
Mediterranean-style diets, Dr. Scarmeas speculated, may be effective against Alzheimer’s by combating inflammation and oxidative stress. Also, a blue-ribbon National Institutes of Health panel recently found significant parallels between cardiovascular health and cognitive health in people over 65 (see the May 2006 Healthletter). So the Mediterranean diet patterns’ demonstrated cardiovascular benefits may translate into protection for the brain.
To learn more: Annals of Neurology, published online in advance of print.
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