People who eat a Mediterranean-style diet are less likely than their peers to develop Alzheimer’s disease, according to new research on elderly Manhattan residents. The study is the first to link brain benefits to a comprehensive dietary pattern rather than to individual foods or nutrients, say the scientists who performed the research.
Traditional Mediterranean menus are rich in fruits and vegetables, fish, and unsaturated fat. They contain little saturated fat from meat or whole-fat dairy products. Meals often feature moderate alcohol consumption.
“This overall dietary pattern is associated with decreased risk of a series of diseases,” says neurologist Nikolaos Scarmeas of Columbia University Medical Center. Those diseases include cardiovascular disorders, diabetes, and certain cancers.
Some studies that have focused on a single component of the diet—frequent fish consumption, for example—have found evidence of neurological benefits. But others have not, perhaps because the elements of the diet don’t have much effect unless they’re combined, Scarmeas says.
To gather information on people’s diets and cognitive status, Columbia researchers went door to door in a largely Hispanic and African American neighborhood near the university. In all, the researchers signed up 2,258 New Yorkers who were at least 65 years old and did not initially have dementia. The volunteers’ average age was 77.
The researchers graded each volunteer’s diet as either a 0 or a 1 on nine specific measures. A volunteer got a point, for instance, by routinely eating more legumes than did most other volunteers; he or she got other points by consuming less meat or less dairy.
The researchers periodically reevaluated each volunteer’s cognitive state. They found that 262 participants developed Alzheimer’s disease during an average of 4 years.
People whose diets initially resembled the Mediterranean diet most closely—those with a diet score of 6 or above—had about a 40 percent reduced risk of developing Alzheimer’s during the study compared with people who scored 3 or below. Volunteers who had moderately Mediterranean-like diets, reflected by a score of 4 or 5 out of 9, faced an intermediate risk of Alzheimer’s, Scarmeas’ team reports in an upcoming Annals of Neurology.
The diet-scoring system used in the study “is far from perfect,” comments Irwin Rosenberg, director of the Nutrition and Neurocognition Laboratory at Tufts University’s Human Nutrition Research Center in Boston. “But it’s at least a step in the direction of trying to judge [Alzheimer’s risk] from dietary patterns rather than simple nutrient associations.”
While the researchers labeled the healthiest pattern as a Mediterranean diet, “it’s not a Mediterranean diet,” comments epidemiologist Martha Clare Morris of Rush University Medical Center in Chicago. By Mediterranean standards, even high-scoring volunteers consumed relatively little olive oil and other healthy oils.
Nevertheless, Morris and others say that the finding supports the contention that a diet heavy in fruits, vegetables, and fish, along with moderate alcohol intake, may protect the brain.