While several well-known studies have found that the Mediterranean diet lowers the risk of Alzheimer’s disease, other studies have failed to confirm these findings. According to authors of a recent paper published in the journal Neurology, differences in the methods used and subjectivity of clinical diagnosis may account for some of the inconsistent results.
To remove bias in clinical assessment, researchers from Columbia University used MRI-based neuroimaging to examine the role of the Mediterranean diet on structural changes that occur due to aging.
The investigators used specific MRI biomarkers to assess structural changes, brain volume and cortical thickness of 674 elderly, dementia-free subjects, whose average age was 80 years.
The multiethnic subjects living in northern Manhattan completed food frequency questionnaires which were used to calculate Mediterranean Diet Scores and determine adherence to the Mediterranean diet.
Results of MRI markers showed that subjects who had a higher Mediterranean diet score and higher adherence to the Mediterranean diet had larger total brain volume, total gray matter volume and total white matter volume compared to those who had a lower adherence to the Mediterranean diet.
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The benefit of higher fish intake and lower meat intake was also observed: Subjects who consumed more fish and less meat had larger total gray matter volume. Similarly, higher fish consumption was associated with larger mean cortical thickness, while those who consumed smaller amounts of meat had larger total brain volume.
The researchers also found that, when adjusted for age, those who consumed alcohol in moderation in addition to consuming more fish and less meat had larger brain volumes.
The results of this study imply that brain shrinkage, a natural physiological change that occurs with aging, may be delayed by consuming the Mediterranean diet, a diet rich in fish, vegetables, legumes, fruits, cereals, nuts and monounsaturated fats such as those found in olive oil.
The authors of the study report that weekly intake of 3 to 5 ounces of fish and reducing meat intake to less than 100 gram daily could protect against brain shrinkage equivalent to 3 to 4 years of aging.
While the exact science behind these findings is not yet known, the study results show that the benefits of consuming the Mediterranean diet extend to delaying brain shrinkage associated with aging and may prevent cognitive decline.