Food for Thought for Alzheimer's Emerges in Mediterranean Diet

October 9, 2006

NEW YORK -- A Mediterranean-style diet -- spare on red meat and heavy on fruits, vegetables, and olive oil -- may help to fend off Alzheimer's disease, reported researchers here.

NEW YORK, Oct. 9 -- A Mediterranean-style diet -- spare on red meat and heavy on fruits, vegetables, and olive oil -- may help to fend off Alzheimer's disease, according to researchers here.

The effect was strongest in people who followed a Mediterranean-type diet most religiously, reported Nikolaos Scarmeas, M.D., of Columbia University, and colleagues, in an early online release from the December issue of Archives of Neurology.

Also, the effect appeared to be independent of vascular risk factors, suggesting that the diet had non-vascular protective benefits, such as antioxidant or anti-inflammatory properties, they wrote.

In a separate study, published by Swedish researchers in the October issue of Archives of Neurology, there was also evidence that dietary supplements containing a prominent Mediterranean diet component -- omega-3 fatty acids -- may reduce the rate of cognitive decline in people with the mildest Alzheimer's disease. Omega-3 didn't seem to slow the progression of more advanced forms of the dementia, they added.

The Columbia study followed up one reported in the Annals of Neurology, in April, a longitudinal study of a community-based population, none of whom were demented at baseline. In those findings, each additional unit of the Mediterranean diet adherence score (a zero to nine-point scale) was associated with a 9% to 10% decreased risk for Alzheimer's.

Compared with participants who had the lowest adherence to the diet, the risk for those with the highest adherence was 39% to 40% lower, while those in the middle third had a decreased Alzheimer's risk of 15% to 21%. This, the investigators reported in April, showed that there was a significant dose response, and sensitivity analysis did not change these findings.

To determine whether those findings would hold up in a different type of analysis, including patients diagnosed with Alzheimer's, the authors conducted a case-control study nested within a community-based cohort in northern Manhattan's Washington Heights and Inwood neighborhoods.

They used validated food-frequency questionnaires administered by trained interviewers to determine the overall diet components over the previous year in 194 patients with a diagnosis of Alzheimer's disease, and 1,790 non-demented people; both groups were part of the Washington Heights-Inwood Columbia Aging Project cohorts.

Using logistic regression models, the authors controlled for gender, ethnicity, level of education, apoliprotein E genotype, caloric intake, smoking, medical comorbidity index, and body mass index.

They also looked for possible mediating effects of vascular variables, including stroke, diabetes, hypertension, heart disease and lipid levels.

They found that higher adherence to the Mediterranean diet was associated with lower risk for Alzheimer's (odds ratio, 0.76, 95% confidence interval, 0.67-0.87, P