It has long been thought that the Mediterranean diet (consisting of fish, vegetables, fruits, nuts, legumes, cereals, and a higher ratio of monounsaturated to saturated fats) may reduce the risk of developing dementia or experiencing cognitive decline. Previous studies have demonstrated that this diet is actually associated with individuals retaining more brain volume and cortical thickness, in areas that usually shrink as a person ages, or develops Alzheimer’s disease.
Recently, researchers sought to investigate such findings, drawing from a population of 512 participants who were either in good health or exhibited increased risk for developing Alzheimer’s disease. All study participants underwent a neuropsychological assessment which was meant to test skills including memory, language, and visuospatial abilities. Additionally, participants completed a questionnaire that assessed how closely they each adhered to the Mediterranean diet.
Using MRI to view important brain structures of these participants, researchers observed what they had initially hypothesised. Namely, participants who closely adhered to the Mediterranean diet were more likely to have greater grey matter volume in areas like the hippocampus and parahippocampal gyrus, which normally deteriorate with age and Alzheimer’s disease. In terms of the cognitive assessment which participants underwent earlier, participants who adhered more closely to the Mediterranean diet scored higher in memory and language tests than participants of similar ages with other dietary preferences.
Furthermore, a subset of 226 participants agreed to undergo a lumbar puncture procedure, which allowed researchers to search for any cerebrospinal fluid proteins which are known predictors of Alzheimer’s disease. Their findings here were quite compelling – participants who adhered more closely to the Mediterranean diet showed decreased levels of phosphorylated tau 181, a biomarker of Alzheimer’s disease. In fact, adhering slightly more to the Mediterranean diet, by just one point on researchers’ dietary questionnaire, was associated with the reversal of around three years of normal ageing!
The general health benefits of a diet limiting processed foods as well as meat and dairy intake have long been noted, particularly with regard to cardiovascular health. But this study and preceding findings seem to suggest that the Mediterranean diet is also uniquely equipped to maintain brain health for ageing individuals. Whether this effect is observed through preservation of cognitive function, or less deterioration in memory-related brain structures, or the inverse association between the Mediterranean diet and pathologic biomarkers of Alzheimer’s disease, this diet may serve as a promising preventative measure for people at risk of developing neurodegenerative diseases.
Original source: Ballarini T, Melo van Lent D, Brunner J, et al. Mediterranean Diet, Alzheimer Disease Biomarkers and Brain Atrophy in Old Age [published online ahead of print, 2021 May 5]. Neurology. 2021;96(24):e2920-e2932. doi:10.1212/WNL.0000000000012067
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Edited by Cyrus Rohani-Shukla