A recent study reported that people who strictly adhered to the Mediterranean diet or the A Priori Diet Quality Score (APDQS) diet during early to middle adulthood were significantly less likely to have poor cognitive functions in midlife than people with low adherence to these diets . But adherence to the Dietary Approaches to Stop Hypertension (DASH) diet during adulthood was not associated with cognitive functions later in life.
Findings come from a study of 2,621 young adults (average age 25), who were interviewed at baseline, 7 years later, and 20 years later, on the frequency and amounts of different food items and beverages they consumed. Dietary pattern scores were generated based on the level of adherence to the Mediterranean diet, DASH diet, and the APDQS diet. These dietary pattern scores were averaged across baseline, year 7, and year 20 to derive the long-term dietary pattern scores for each individual. Then the participants' cognitive functions were assessed in years 25 and 30, at the average ages of 50 and 55, respectively.
People who scored in the top third with regards to adherence to the Mediterranean diet during adulthood were 46 percent less likely to have poor overall cognitive functions in their 50s than people who scored in the low third. Also, people who scored in the top third in adherence to the APDQS diet during adulthood were 52 percent less likely to have poor overall cognitive functions in their midlife than people scoring in the low third. When comparing people with high versus low Mediterranean and APDQS diet scores, fruit and vegetable servings were almost double; people with high adherence to these two diets ate on average 4 servings of fruit and 5 servings of vegetables per day. It is worth noting that there were no associations between the baseline dietary pattern score (at age 25) and cognitive scores 30 years later, suggesting that a long-term healthy diet throughout adulthood is important for cognitive health later in life.
High adherence to the DASH diet was not associated with differences in cognitive functions in midlife, but a recent study reported that the DASH diet when combined with aerobic exercise is associated with better cognitive functions .
Because this study was an observational study and not a randomized clinical trial, it was not designed to prove that the Mediterranean or the APDQS diet is responsible for better cognitive functions. People who eat a healthy diet may be more likely to have other healthy habits that are good for the brain. But it is worth noting that the associations between high Mediterranean and APDQS dietary scores and better cognitive functions remained significant even after controlling for demographic, lifestyle, and health factors.
The mechanisms by which a healthy diet influences midlife cognitive functions are not yet clear, but may be mediated by dietary components with antioxidant (e.g., fruits, vegetables) and anti-inflammatory (e.g., omega-3 fatty acids, polyphenols) properties. A healthy diet also decreases the risks for type-2 diabetes, high blood pressure, and high cholesterol, all of which have been associated with cognitive decline and dementia.
Additional research is needed to determine which combination of foods and nutrients are best for optimal brain health. But based on this study and previous ones, a heart-healthy diet rich in fruits, vegetables, legumes, fish, and nuts, and low in full-fat dairy and red meat appear to be beneficial.
Yuko Hara, PhD, is Director of Aging and Alzheimer's Prevention at the Alzheimer's Drug Discovery Foundation. Dr. Hara was previously an Assistant Professor in Neuroscience at the Icahn School of Medicine at Mount Sinai, where she remains an adjunct faculty member. Her research focused on brain aging, specifically how estrogens and reproductive aging influence the aging brain's synapses and mitochondria. She earned a doctorate in neurology and neuroscience at Weill Graduate School of Medical Sciences of Cornell University and a bachelor's degree in biology from Cornell University, with additional study at Keio University in Japan. Dr. Hara has authored numerous peer-reviewed publications, including articles in PNAS and Journal of Neuroscience.
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