MEDITERRANEAN diets, supplemented with additional portions of antioxidant-rich extra virgin olive oil or mixed nuts, could protect cognitive functioning in older adults. A recent study in Spain has provided evidence that following a Mediterranean-style diet can lead to improvements in cognitive function thereby counteracting age-related cognitive decline, which may lead to dementia.
Dr Emilio Ros, Institut d’Investigacions Biomediques August Pi Sunyer, Hospital Clinic, Barcelona, Spain and co-authors tested this hypothesis by analysing the effects of Mediterranean diets supplemented with olive oil or nuts compared with a low-fat control diet. The study was a randomised clinical trial which followed participants’ cognitive changes over a median period of 4 years. A total of 155 subjects were randomly allocated to follow a Mediterranean diet supplemented with 1 L of extra virgin olive oil per week. Another 147 subjects were assigned to follow a Mediterranean diet supplemented with 30 g per day of mixed nuts, and were compared to a control group of 145 participants who followed a diet where they received advice to reduce dietary fat.
Follow-up cognitive tests were made available in 334 subjects after a median of 4 years of dietary intervention. The researchers discovered a total of 37 cases of mild cognitive impairment among the subjects: 17 (13.4%), 8 (7.1%), and 12 (12.6%) in the extra olive oil group, the mixed nuts group, and the control group, respectively. Subjects in the control group experienced significant decreases in each measured composite of cognitive function. However, the two Mediterranean diet groups produced different improvements in cognitive function. “The group with nuts did better compared to the control group in memory tests, memorising names or words, while the olive oil group did better on tests that require speed of thought, your frontal function, your executive function,” said Dr Ros.
Although the study was a randomised clinical trial, it possesses limitations. Not all subjects received follow-up cognitive testing, while adherence to all three diets cannot be assured. The researchers therefore intend to carry out further investigation into the theory. “Our results suggest that in an older population, a Mediterranean diet supplemented with olive oil or nuts may counteract age-related cognitive decline,” the authors concluded. “The lack of effective treatments for cognitive decline and dementia points to the need of preventive strategies to delay the onset and/or minimise the effects of these devastating conditions.”