The results are published in the American Journal of Clinical Nutrition.
Included in the study were 3,759 older residents of the South side of Chicago who are part of the Chicago Healthy Aging Project, an ongoing evaluation of cognitive health in adults over the age of 65. Every three years, the study participants, age 65 and older, underwent a cognitive assessment that tested such things as memory and basic math skills. Participants also filled out a questionnaire on the frequency with which they consumed 139 food items ranging from cereals and olive oil to red meat and alcohol.
The researchers then analyzed how closely each of the study participants adhered to a Mediterranean diet, which includes daily consumption of such foods as fruit, vegetables, legumes, olive oil, fish, potatoes and nonrefined cereals, as well as wine.
Out of a maximum score of 55, which would indicate complete adherence to the Mediterranean diet, the average study participant scored 28. Those with the higher scores were also the individuals whose cognitive tests showed a slower rate of decline, even when other factors that might account for the result, such as education level, were considered.
The researchers also analyzed how closely study participants adhered to the Healthy Eating Index—2005, which is based on the recommendations from the 2005 Dietary Guidelines for Americans. Higher scores indicating closer adherence to this index, which gives less weight to fish, legumes and moderate alcohol intake, did not correspond with differences in rates of cognitive decline.
Christy Tangney, PhD, lead author of the study and associate professor of clinical nutrition at Rush University, said that the results add to other studies showing that a Mediterranean diet reduces the risk of heart disease, certain cancers and diabetes.
“The more we can incorporate vegetables, olive oil, and fish into our diets and moderate wine consumption, the better for our aging brains and bodies,” Tangney said.
Other researchers at Rush involved in the study were Mary Kwasny, ScD, Hong Li, Robert Wilson, PhD, Dr. Denis Evans, and Martha Clare Morris, ScD.
The study was supported by a grant from the National Institute on Aging.