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Can the Mediterranean diet prevent Alzheimer’s?
(October 2006)

A variety of dietary components and vitamins have been touted as being able to prevent mental decline and Alzheimer’s, but the evidence has been contradictory and unpersuasive.  The Mediterranean diet, high in fruits, vegetables, legumes, olive oil, cereals, and fish, plus regular ingestion of wine, has been associated with a lower risk of heart attack and stroke and even has been thought to increase longevity.  An article published on line, April 18, 2006, in the Annals of Neurology claims that the Mediterranean diet will also reduce the risk of Alzheimer’s.

A total of 2,226 men and women, average age 77 years, were followed for an average of four years (range 0.2 to 13.9 years); 262 developed Alzheimer’s.  At enrollment and subsequently, dietary histories were taken and scored from 0 to 9 according to adherence to the Mediterranean diet.  At each followup visit, twelve neuropsychologic tests were administered that measured mental function.  Those with the greatest adherence to the diet had a 40 percent reduced risk of developing Alzheimer’s disease.

Commentary: This is an interesting study and maybe the Mediterranean diet is protective, but any conclusions must await confirmatory studies.  The overwhelming majority of the Alzheimer’s cases were detected within four years or less after enrollment.  Since mental abnormalities may be present for years prior to a diagnosis of Alzheimer’s, there is a strong possibility of mistakes in dietary recall.  Alzheimer’s is also related to vascular factors, such as hypertension.  A composite score for accompanying chronic diseases, including hypertension and heart attacks, was created, but it seems to under-focus on vascular factors related to Alzheimer’s and is open to misclassification.

It would be nice if a prudent diet could either prevent or postpone Alzheimer’s, but that possibility is far from adequately documented.

Scarmeas, N., et al.  Mediterranean diet and risk for Alzheimer’s disease.  Annals of Neurology.  April 18, 2006.  On line.