In previous research, Dr. Nikolaos Scarmeas of Columbia University Medical Center in New York and colleagues showed that high adherence to a Mediterranean diet -- which is rich in olive oil, fruits and vegetables, nuts, grains, and fish, but low in meat, alcohol, and dairy products -- might be associated with a lower risk of Alzheimer's disease and may lengthen survival in people with Alzheimer's disease. (See Reuters Health report, Aug. 11, 2009.)

This latest research suggests that the associations may be partially mediated via protection from brain infarction.

The findings are based on a study of 712 community-dwelling cognitively normal subjects aged 65 and older (average age, 80) who were classified into three groups based on how closely they followed a Mediterranean-like diet (low, moderate, and high adherence). Brain MRI scans were performed 5.8 years after diet assessment.

Some of the participants were following a diet "closer to a Mediterranean ideal, while others were farther away and we correlated their Mediterranean diet score with their risk of having an infarct on brain MRI," Dr. Scarmeas explained in a telephone interview with Reuters Health.

A total of 238 study subjects had at least one cerebral infarct. In unadjusted analyses, compared to subjects with low adherence to a Mediterranean diet, moderately adherent patients had a 21% reduced probability of having an infarct (OR, 0.79), while those with high adherence had a 36.1% reduced probability (OR, 0.64).

After adjustment for demographics and vascular risk factors (including heart disease, hypertension, smoking history, cholesterol and APOE4 status), the strength of the association between close adherence to Mediterranean-type diet and reduced brain infarction remained essentially unchanged.

"In this study, not eating a Mediterranean-like diet has about the same effect on the brain as having high blood pressure," Dr. Scarmeas noted in a statement from the American Academy of Neurology.

While both men and women seemed to benefit from a Mediterranean-type diet, "it seems that the effect was a little bit stronger for women," he told Reuters Health. He and his colleagues note in their report that women and men, respectively, had 45% vs 15.6% reduced probabilities of infarction with high adherence.

"We are still investigating associations of the Mediterranean diet with inflammatory or oxidative pathways and we are planning to relate this diet with other MRI indices, such as white matter hyperintensities, atrophy and so forth," Dr. Scarmeas said.