Reference
Arjmand G, Abbas-Zadeh M, Eftekhari MH. Effect of MIND diet intervention on cognitive performance and brain structure in healthy obese women: a randomized controlled trial. Sci Rep. 2022;12(1):2871.
Study Objective
To study the effects of the Mediterranean-DASH (Dietary Approach to Stop Hypertension) Intervention for Neurodegenerative Delay (MIND) dietary pattern on brain structure and cognitive performance in healthy, obese middle-aged women
Key Takeaway
Adherence to the MIND dietary pattern for 3 months produced significantly higher improvements in cognitive performance and increased surface area in the inferior frontal gyrus compared to the control group.
Design
Randomized, controlled trial of 3-months duration
Participants
All 37 selected participants completed the study; 22 were in the MIND diet group and 15 in the control group. All were healthy, obese women living in Iran. None had a history of diabetes or hypertension. All were classified as obese. The mean age was 48±5.3 years; 83.8% were married.
Intervention
Participants in the intervention group followed a calorie-restricted MIND diet for 3 months. Those in the control group followed a calorie-restricted diet for the same duration. Both groups were instructed to eat the same balance of macronutrients.
The control group received general recommendations for a reduced-calorie diet, while the MIND group received intensive instruction in specific foods to eat. A consistent dietician followed up with participants weekly.
Study Parameters Assessed
Investigators assessed all clinical and anthropometric parameters at baseline and at the end of study (at 3 months), excepting physical activity, which was assessed at baseline and monthly.
Dietary intake was assessed via a food frequency questionnaire and physical activity.
The primary endpoint, cognitive performance, was assessed using a complex battery of neurocognitive tests.
Secondary endpoint assessments included clinical and anthropometric data (body weight and composition, plasma brain-derived neurotrophic factor [BDNF], amyloid-beta, and homocysteine) and assessments of changes in brain structure (using MRI). Note that due to cost or fear of being in the device, MRI scans were performed on only a subgroup of 11 participants in each group.
Primary Outcome
This study primarily assessed changes in cognitive performance. Secondarily, it looked at changes in anthropometric parameters, food intake, neuronal factors, and brain structure.
Key Findings
After 3 months, the MIND group compared to the control group showed significantly improved scores on all but 2 cognitive function tests, with those 2 showing a similar but nonsignificant improvement trend (P<0.05). Within-group comparison showed improved cognitive testing scores in both groups, which the authors suggest may be due to a learning effect of becoming familiar with test content.
Food and energy intake did not differ between groups at baseline. At 3 months, both groups saw improvements in their diet composition, with the MIND group generally showing greater increases in specific foods included in the MIND diet and greater reductions in foods to exclude. Though both groups took in significantly more leafy greens (P<0.001 for MIND group and P<0.019 for control group), the actual increase in servings per day was 1 to 2 per day for the MIND group and about 0.3 servings for the control group.
Homocysteine levels were significantly reduced in the MIND group (P=0.010); also there was a nonsignificant trend toward improvement in amyloid beta (P=0.09) and BDNF levels (P=0.248) in the MIND group. All neuronal factors showed greater improvements in the MIND group than in the control group.
There was a significant increase in the surface area of the inferior frontal gyrus in the MIND group compared to the control group (P=0.018). This surface area decreased in the control group.
There was a nonsignificant decrease in cerebellum white matter and cortex volume in both groups, but with greater decrease in the MIND group.
Transparency
The authors declared no competing interests.
Practice Implications
The growing obesity epidemic is spawning multiple health conditions that are costing us our personal and societal well-being and oftentimes our lives. It is finding its way into younger and younger populations with the highest prevalence for obesity and severe obesity in the United States occurring in middle-aged adults.1 Obesity is linked to accelerated cognitive decline and dementia.2 What used to be called “senility” because it appeared primarily in elders is now manifesting in the “young old” and the middle-aged.
Years of Alzheimer's disease dementia drug research has not yet yielded a magic bullet. Healthy lifestyle practices such as physical activity and eating well, along with blood pressure control and cognitive training, hold some of the greatest promise for sustained and sustainable cognitive health and dementia prevention/delay.3
As a culinary translator, health-supportive chef, and oncology clinical nurse specialist, I look upon this study with great interest. There are many implications for clinical practice: the advisability of prescribing the MIND diet, sufficient adherence to the diet to realize effects, and education and support to maximize adherence.
This well-designed randomized, controlled trial by Arjmand and colleagues is important in several ways. It adds to the growing body of evidence that dietary interventions may improve cognitive health; it lends support to conducting longer interventions with longer-term follow-up to see if there is a sustained delaying, if not preventive effect, on cognitive decline in middle-aged obese individuals; it focuses on the middle-age population, where cognitive decline related to obesity is beginning to manifest; it demonstrated, at least in this population, that it is feasible to follow the MIND diet for 3 months and be able to see measurable improvements.
What used to be called 'senility' because it appeared primarily in elders is now manifesting in the 'young old' and the middle-aged.
Though longer-term studies have been observational, they do give some indication of how long people can adhere to the MIND eating pattern. An observational study of the MIND diet compared to the Mediterranean and DASH diets in adults aged 58 to 98 years found that after an average of 4.5 years, the highest adherence to all 3 diets may lower Alzheimer's disease risk. However, the MIND diet provided the greatest risk reduction (53%). Morris and colleagues observed that elders aged around 81 years with the highest adherence to the MIND diet during an average of almost 5 years had the most substantial slowing of cognitive decline.4 It may also be that the known beneficial effects of these diets on cardiovascular health may contribute to its beneficial cognitive effects.
So, though the results of this and the predecessor studies by Morris and colleagues are still preliminary, there is plenty of other evidence to lean on to recommend the MIND diet. This dietary pattern is basically a fusion of the Mediterranean diet (MD) and DASH diet, both with an emphasis on eating foods thought to enhance cognitive function and brain health: whole grains, berries, leafy greens, fish, poultry, beans, nuts, and olive oil. There is also a strong recommendation to limit foods linked to poorer cognitive function: butter, cheese, red meat, fried foods, and sweets.
If you are a natural medicine provider, you are likely looking at that list of foods and thinking that those are the same foods you’d recommend in chronic disease prevention and management. In general, MIND, DASH, and MD are safe for most people. These diets seem particularly suited to improving imbalances in the terrain that makes the body more susceptible to poor health. There are multiple well-designed RCTs, including this one, indicating the benefit of these types of diets to several body terrain elements. Of note are the anti-inflammatory and antioxidant effects. Many of the benefits may be modulated through the diet's interaction with the gut microbiome and epigenetics.5-11
The evidence for the MIND diet for improving cognitive function and delaying cognitive decline is preliminary. However, if paired with the more robust evidence base for the MD and DASH diets’ effects on obesity and its sequalae, it seems quite reasonable to recommend this diet in obese patients at risk of dementia or already symptomatic of cognitive decline. I would be transparent that the MIND diet is not a magic bullet, and the evidence is young yet. I would likely not recommend this diet in isolation, but rather combined with other lifestyle practices such as physical activity and other interventions such as cognitive training and blood pressure control, as outlined by the National Academy of Sciences.12
So as not to overwhelm the patient, I would suggest an individualized approach to incorporating these lifestyle changes and interventions with realistic goal setting and targets. I also would help the patient explore and understand any preventive and treatment options recommended by their conventional healthcare practitioner to delay or prevent dementia. If there are safe, effective conventional options, I would suggest lifestyle practices be used in an integrative, rather than alternative, approach.
One of the likely reasons there was such high adherence to the intervention in this study is that the same dietician gave intensive instructions and weekly follow-up to support and ensure adherence. One of the biggest challenges in recommending dietary change is the patient being able to translate your prescription to their plate. A prudent diet pattern such as the MIND diet may not be familiar to your patient. Patients will often say they don’t have time to learn about the diet and all the things that go into procuring and preparing the food. With the rising prices of food, patients may tell you they can’t afford to eat healthily. They may tell you that work and family obligations, cultural diet expectations and traditions, and lack of support are getting in the way. Yet, adherence to the diet as a way of life for a sustained period is going to be the key to its success. Curiously, the authors of the study under review pointed out that they had to change the study population to all women because “at the beginning of the study, we noticed that the male population had low compliance with the study instructions.”
In the clinical practice world, we usually are not able to pick and choose only patients who are able to adhere to diet recommendations. I’ve learned that it’s important to build into my practice a deep curiosity about the individuals whom I serve, including knowing what stands in the way of, as well as what enhances, their chances of success in taking care of themselves. I consider that the path to a healthier lifestyle involves many guides by the patient’s side. What may start as a recommendation from you needs to be bolstered by referring patients to other people and toward informational and support resources to educate, coach, and support them in overcoming barriers and building upon their strengths in making change.
Finally, if you choose to recommend the MIND diet, you can contribute to our knowledge about its safety and effectiveness by keeping good notes and writing up case reports. According to David Wiley, MD, who helped develop the CARE (CAse REports) guidelines for case reporting, these reports are 1 of the fastest growing areas of medical research in peer-reviewed journals. The guidelines “support an increase in the accuracy, transparency, and usefulness of case reports.”13
Study Limitations
The primary limitations of this study are its short length, limiting our ability to predict the sustainability of effects; small sample size; and the narrow population, restricting generalizability. Another limitation is the authors’ one-sided and somewhat unclear explanation of the decrease in cerebellar volume and white matter. At first glance, I thought this result, reported as a positive outcome in brain structure change, was a typo. When I searched the literature for the significance of this change in brain structure, there were only a few articles, and they described decreases in white matter volume as a sign of pathology such as in multiple sclerosis. Zdanovskis and colleagues found those with normal cognitive function had a nonsignificantly higher cerebellar cortex and white matter volume than those with mild cognitive impairment or dementia.14 I did follow Arjmand et al’s citations related to their results. In a small, controlled study of healthy, obese subjects and healthy, lean subjects, there were greater white matter volumes, including in basal brain structures, in those who were obese. Further, white matter volume in these structures was positively correlated with waist-to-hip ratio.15 A scientific review of preclinical and clinical evidence noted that the cerebellum is involved in feeding behavior, having both inhibitory and excitatory effects. The review cited differences in cerebellar responses to meals in lean vs obese healthy men; one difference was that the latter group experienced greater decreases in cerebellar cerebral blood flow.16 I don’t think we have enough understanding of the clinical significance of decreased cerebellar white matter/volume in middle-aged, obese women to determine if it is a positive or negative outcome in this study.
