Review of: Dhana K et al, J Alzheimers Dis 2021;83(2):683–692

Study Type: Prospective cohort study

The MIND diet, a fusion of the Mediterranean and Dietary Approaches to Stop Hypertension (DASH) diets, has previously been associated with a reduced risk of dementia in cognitively intact older adults (OAs) (Morris MC et al, Alzheimers Dement 2015;11(9):1007–1014). But are there potential benefits on cognitive function in OAs with existing brain pathologies like mild cognitive impairment and Alzheimer’s disease (AD)?

This prospective cohort study involved 569 OAs enrolled in the Rush Memory and Aging project. Participants underwent neuropsychological testing, and researchers assessed their dietary habits by asking about their usual consumption frequency of 144 food items over the past year. The MIND diet score was calculated as the sum of 15 component scores, including:

• Ten brain-healthy food groups: green leafy vegetables, other vegetables, nuts, berries, beans/legumes, fish, olive oil, whole grains, poultry, wine
• Five unhealthy food groups: red meat, fried/fast foods, sweets, butter, cheese

Subjects enrolled in the study were followed until their deaths. Autopsies were conducted to examine brain pathology.

Researchers found that two-thirds of the participants had dementia pathology postmortem, though only one-third received a clinical AD diagnosis around the time of death. They observed an association between higher MIND diet scores and higher cognitive scores, as well as a slower decline in cognitive scores. The MIND diet was not associated with brain pathology, suggesting that its mechanism supporting cognitive resilience works in an unrelated manner.

Carlat Take

This well-designed, population-based study generated results consistent with the hypothesis that the MIND diet is associated with improved cognitive function, independent of other risk factors for dementia. However, correlation does not imply causality. It is possible that people with dementia or cognitive limitations may choose less healthy foods due to their cognitive impairments. Also keep in mind that minoritized older adults often live in food deserts without access to healthy foods and/or lack financial resources to purchase foods advised through the MIND diet. Nonetheless, the MIND diet is based on diets that have known cardiovascular benefits, which in turn may improve brain health. We recommend management of modifiable cardiovascular risk factors such as hypertension and smoking in addition to following a brain-healthy diet (green leafy vegetables, berries, olive oil, beans, whole grains, and fish) and limiting processed foods and saturated fats. For more on the MIND diet, see www.­tinyurl.com/2z42nmkw.