Mediterranean Diet Reduces Risk of Alzheimer's

HD Lighthouse Contributing Editor's Comment:

Readers often write and ask if there is an HD diet. Studies with mouse models of Huntington's Disease and neurodegeneration in general has suggested that foods which are high in antioxidants and Omega-3 fatty acids are a good bet, but is there any overall dietary strategy that people at risk might pursue to stay healthy as long as possible?

Lighthouse founder Jerry Lampson was very interested in the Mediterranean diet and a growing body of research suggests that it does indeed convey a variety of health advantages, including living longer (Trichopoulou 2005). In the research described below, Nikolaos Scarmeas, M.D., and his colleagues present evidence that those who follow the Mediterranean diet are less like likely to develop Alzheimer's and that this is independent of the decreased likelihood of vascular disease.

The Mediterranean diet was defined in this study as high consumption of fruits, vegetables, cereals, legumes, and fish, low consumption of meat and dairy products, mild to moderate consumption of alcohol, and more monounsaturated fats such as olive oil and less saturated fat such as butter.

While the Mediterranean diet is not a Huntington's Disease diet, the Alzheimer's prevention results indicate that it might be helpful.

The full article can be found here:
http://archneur.ama-assn.org/cgi/content/full/63.12.noc60109#REF-NOC60109-20

References:

Trichopoulou A, Orfanos P, Norat T, et al. Modified Mediterranean diet and survival: EPIC-elderly prospective cohort study. BMJ. 2005;330:991.

-- Marsha L. Miller, Ph.D.
Posted to the HDL: 21 Oct 2006

Nikolaos Scarmeas, M.D.

Journal Abstract

Objectives:

To examine the association between the Mediterranean diet (MeDi) and Alzheimer disease (AD) in a different AD population and to investigate possible mediation by vascular pathways.

Design, Setting, Patients, and Main Outcome Measures:

A case-control study nested within a community-based cohort in New York, NY. Adherence to the MeDi (0- to 9-point scale with higher scores indicating higher adherence) was the main predictor of AD status (194 patients with AD vs 1790 nondemented subjects) in logistic regression models that were adjusted for cohort, age, sex, ethnicity, education, apolipoprotein E genotype, caloric intake, smoking, medical comorbidity index, and body mass index (calculated as weight in kilograms divided by height in meters squared). We investigated whether there was attenuation of the association between MeDi and AD when vascular variables (stroke, diabetes mellitus, hypertension, heart disease, lipid levels) were simultaneously introduced in the models (which would constitute evidence of mediation).

Results:

Higher adherence to the MeDi was associated with lower risk for AD (odds ratio, 0.76; 95% confidence interval, 0.67-0.87; P<.001). Compared with subjects in the lowest MeDi tertile, subjects in the middle MeDi tertile had an odds ratio of 0.47 (95% confidence interval, 0.29-0.76) and those at the highest tertile an odds ratio of 0.32 (95% confidence interval, 0.17-0.59) for AD (P for trend <.001). Introduction of the vascular variables in the model did not change the magnitude of the association. CONCLUSIONS: We note once more that higher adherence to the MeDi is associated with a reduced risk for AD. The association does not seem to be mediated by vascular comorbidity. This could be the result of either other biological mechanisms (oxidative or inflammatory) being implicated or measurement error of the vascular variables.

The Press Release:

Mediterranean Diet Associated with Reduced Risk of Alzheimer's Disease

CHICAGO—Eating a Mediterranean diet, which emphasizes fruits, vegetables and olive oil and includes little red meat, is associated with a lower risk for Alzheimer’s disease, according to an article posted online today that will appear in the December 2006 print issue of Archives of Neurology, one of the JAMA/Archives journals. This association persisted even when researchers considered whether individuals had vascular diseases—diseases of the blood vessels, such as stroke, heart disease and diabetes—suggesting that the diet may work through different pathways to reduce Alzheimer’s disease risk.

The Mediterranean diet consists of high amounts of fruits, vegetables, legumes, cereals and fish, mild to moderate amounts of alcohol and low amounts of red meat and dairy products, according to background information in the article. This diet has been associated with a lower risk for several diseases and risk factors, including cancer, obesity, high cholesterol, high blood pressure, problems with processing glucose that may lead to diabetes, coronary heart disease and overall death.

Nikolaos Scarmeas, M.D., and colleagues at Columbia University, New York, studied whether the Mediterranean diet could also help prevent Alzheimer’s disease—a debilitating neurodegenerative disease—in a group of 1,984 adults with an average age of 76.3. The participants, 194 of whom already had Alzheimer’s disease and 1,790 of whom did not, were given complete physical and neurological examinations and a series of tests of brain function. Their diet over the previous year was analyzed and scored based on how closely it adhered to the principles of the Mediterranean diet—scores ranged from zero to nine, with higher scores indicating eating patterns that aligned closely with the Mediterranean diet. The researchers obtained information about vascular disease diagnoses from the exams, participants’ or relatives’ reports and medical records.

Eating a diet that closely followed the Mediterranean model was associated with a significantly lower risk for Alzheimer’s disease. For each additional unit on the diet score, risk for Alzheimer’s disease decreased by 19 to 24 percent. After the researchers considered other factors that could influence Alzheimer’s disease risk, including age and body mass index, those who were in the top one-third of the diet scores had 68 percent lower odds of having Alzheimer’s disease than those in the bottom one-third, and those in the middle-one third had 53 percent lower odds.

Growing evidence links the Mediterranean diet to a reduced risk for vascular disease and suggests that vascular risk factors may contribute to the risk for Alzheimer’s disease, the authors write. “Thus, vascular variables are likely to be in the causal pathway between the Mediterranean diet and Alzheimer’s disease and should be considered as possible mediators,” they continue. “However, when we considered vascular risk factors in our models, the association between the Mediterranean diet and Alzheimer’s disease did not change. This was the case despite our attempt to capture vascular comorbidity in the most complete possible way by simultaneously considering both a long list and alternative definitions of vascular variables.”

“This could be the result of either other biological mechanisms (oxidative or inflammatory) being implicated or measurement error of the vascular variables,” the authors conclude.

Source: Archives of Neurology 2006;63:(doi:10.1001/archneur.63.12.noc60109).

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