Mediterranean Diet Improves Cognition: the PREDIMED-NAVARRA Randomised Trial

Study Questions:

Does consuming a Mediterranean diet improve cognitive function?

Methods:

The PREDIMED (PREvención con DIeta MEDiterránea) study was a randomized, parallel-group, cardiovascular primary prevention trial conducted in Spain from May 2005 to December 2010, which compared two interventions with MedDiet (supplemented with extra virgin olive oil [EVOO] and supplemented with mixed nuts) versus the low-fat diet usually recommended for the primary prevention of cardiovascular disease (CVD) in a high-risk population. Participants were community-dwelling men (ages 55-80 years) and women (ages 60-80 years), initially free of CVD, but at high vascular risk because of the presence of either type 2 diabetes or at least three of the following major risk factors: current smoking, hypertension, dyslipidemia, overweight, or family history of premature CVD. Exclusion criteria included previous history of CVD, any severe chronic illness, and illiteracy. Global cognitive performance was examined by Mini-Mental State Examination (MMSE) and Clock Drawing Test (CDT) after 6.5 years of nutritional intervention. Researchers who assessed the outcome were blinded to group assignment.

Results:

A total of 552 participants completed cognitive testing and were included in the present analysis. This cohort had a mean age of 74.6 (standard deviation 5.7) years at time of cognitive evaluation, and 44.6% were men. By study design, the cohort had a high prevalence of hypertension, dyslipidemia, and type 2 diabetes. After adjustment for sex, age, education, apolipoprotein E genotype, family history of cognitive impairment/dementia, smoking, physical activity, body mass index, hypertension, dyslipidemia, diabetes, and alcohol and total energy intake, participants allocated to the MedDiet + EVOO showed higher mean MMSE and CDT scores with significant differences versus control (adjusted differences: +0.62; 95% confidence interval [CI], +0.18 to +1.05; p = 0.005 for MMSE and +0.51; 95% CI, +0.20 to +0.82; p = 0.001 for CDT). The adjusted means of MMSE and CDT scores were also higher for participants allocated to the MedDiet + Nuts versus control (adjusted differences: +0.57; 95% CI, +0.11 to +1.03; p = 0.015 for MMSE and +0.33; 95% CI, +0.003 to +0.67; p = 0.048 for CDT). These results did not differ after controlling for incident depression.

Conclusions:

The investigators concluded that an intervention with a Mediterranean dietary pattern enhanced with either EVOO or nuts appears to improve cognition compared with a low-fat diet.

Perspective:

These data suggest that even among adults at high risk for CVD, lifestyle modification, in particular a Mediterranean dietary pattern, may improve brain health. Given the projected increase in the number or adults with dementia, possibly improving dietary factors along with regular physical activity may reduce the number of elderly with cognitive impairment.

Clinical Topics: Diabetes and Cardiometabolic Disease, Dyslipidemia, Prevention, Diet, Hypertension, Smoking, Sleep Apnea

Keywords: Life Style, Chronic Disease, Psychiatry, Overweight, Diabetes Mellitus, Type 2, Risk Factors, Cognition Disorders, Smoking, Primary Prevention, Dyslipidemias, Body Mass Index, Dementia, Spain, Cardiovascular Diseases, Motor Activity, Energy Intake, Diet, Fat-Restricted, Genotype, Hypertension, Brain


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