MIND diet study shows ‘short-term’ impact on cognition

Recent research underscores the significance of committing to the MIND diet over the long term for optimal brain health benefits.

“The benefits within the new study’s three-year clinical trial weren’t as impressive as we’ve seen with the MIND diet observational studies in the past, but there were improvements in cognition in the short-term, consistent with the longer-term observational data,” said Lisa Barnes, PhD, the lead study author and associate director of the Alzheimer’s Disease Research Center at RUSH.

According to the study published in The New England Journal of Medicine, participants in the MIND diet group showed no significant statistical difference in cognitive change compared to the usual diet control group over the three-year period. Both groups were coached to reduce calories by 250 kilocalories per day, but a significant improvement was observed during the first two years.

Barnes stated, “What we saw was improvement in cognition in both groups, but the MIND diet intervention group had a slightly better improvement in cognition, although not significantly better. Both groups lost approximately 5 kilograms over three years, suggesting that it could have been weight loss that benefited cognition in this trial.”

The MIND diet, a blend of the Mediterranean and DASH diets, has been recognized among the top five diets by U.S. News & World Report for six consecutive years. The recent clinical trial was the first to evaluate the diet’s effects on cognitive abilities in a large group of individuals aged 65 or older without cognitive impairment.

Barnes emphasized the link between diet and health, stating, “There is established research that shows that a person’s diet affects health. The participants in this study had to have sub-optimal diets as determined by a score of 8 or less on a diet screening instrument before the study even began. It is reasonable to think that either they were going to maintain their cognition or decrease the rate of cognitive decline in the future.”

She also acknowledged that the improvement in cognition observed during the first year of the study could have been influenced by practice effects on the cognitive tests. This improvement was evident in both the control diet, which focused on caloric restriction, and the MIND diet intervention group.

The MIND diet, developed in 2015 by Martha Clare Morris, ScD, and her colleagues, is based on compelling research on foods and nutrients that impact brain health. It includes nine “brain-healthy food groups,” such as chicken, fish, green leafy vegetables, berries, and nuts, and advises against five unhealthy groups: red meat, butter and stick margarine, full-fat cheese, pastries and sweets, and fried foods. Previous studies by Morris and her team demonstrated that the MIND diet could slow cognitive decline and reduce the risk of developing Alzheimer’s disease, even if not strictly followed.

The latest randomized, Phase III trial, “MIND Diet for Prevention of Cognitive Decline in Older Persons,” enrolled 604 individuals who were overweight, had a suboptimal diet, and had a family history of Alzheimer’s disease. The trial involved two different diet interventions, each with dietary counseling and a mild calorie restriction of 250 calories per day for weight loss.

Participants received regular phone and in-person consultations, as well as occasional group sessions, throughout the three-year study. Evaluations were conducted five times during the study period, assessing mental abilities, blood pressure, diet, physical activity, health conditions, and medication use.

Jennifer Ventrelle, assistant professor in the Departments of Preventive Medicine and Clinical Nutrition and lead dietitian on the MIND diet trial at RUSH, highlighted the support and accountability provided to both groups by trained registered dietitians. She noted that while all participants improved on average, this extensive support made it challenging to detect significant differences between the two groups within the relatively short study duration. Future research will explore variations in coaching and support in individuals following the MIND diet compared to those on a usual diet.

By the end of the study, participants achieved an average weight loss of approximately 5.5% of their initial body weight, surpassing the study’s target of 3%, which is considered clinically significant in preventing or improving adverse health outcomes, Ventrelle added.

“The average MIND score at the end of three years for the MIND group was 11.0 and 8.3 for the control group, placing both groups in a therapeutic range to slow cognitive decline and lower the risk for Alzheimer’s disease, according to previous studies. The significant weight loss and improved MIND scores suggest that the control group also improved their diet and may suggest that following the MIND diet at a score of at least 8.3, coupled with at least a 250-calorie reduction to produce weight loss, may improve cognition. More research is needed to confirm this,” Ventrelle stated.

Barnes reiterated the importance of randomized trials in establishing a cause-and-effect relationship between diet and Alzheimer’s disease incidence. She acknowledged that despite the healthy diet of the control group at the beginning of the trial, their cognition improved slightly over time. Moving forward, specific food groups and their associations with biomarkers measured in the blood will be examined to determine the potential influence of certain nutrients and food groups on cognitive health, considering the participants’ relatively healthy dietary perspective at the start.

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