An international cohort of 31,456 subjects aged 55 and older from 40 countries completed a Mini-Mental State Examination (MMSE) during baseline testing and at least once during follow-up. Each participant provided dietary information and was measured on cognitive function/decline over the period of 5 years. The study did not focus on the Mediterranean diet specifically but rather on the quality of each subject’s diet. The results showed that a diet considered high in quality eating index preserved cognition in patients at high risk for cardiovascular disease and mental decline. According to the researchers, the most likely explanation for the link between a healthy diet and better cognitive function is through improved cardiovascular function.
The observational nature of the study does not allow to establish causation and the MMSE scale has been criticized by some as an insensitive measure to changes in cognitive function. However, thanks to the large size and international origin of the sample, the results of the study are most likely generalizable.