MIND diet not superior to standard diet for preventing cognitive decline among older adults

The study, published in The New England Journal of Medicine, found no significant difference in cognition and brain MRI outcomes from baseline to year 3 in overweight or obese people with a family history of dementia who followed the MIND diet versus those who followed the control diet with mild caloric restriction.

Observational studies have shown that dietary patterns may protect against cognitive decline, but data from clinical trials are scarce. The Mediterranean–DASH Intervention for Neurodegenerative Delay, known as the MIND diet, is a hybrid of the DASH diet and Mediterranean diet, with modifications to include foods that have been putatively associated with reduced dementia risk.

Lisa L. Barnes, Rush University Medical Center, Chicago, IL, and colleagues aimed to test the cognitive effects of the MIND diet with mild caloric restriction versus a control diet with mild caloric restriction in older adults without cognitive impairment but with a family history of dementia.

For this purpose, the researchers performed a two-site, randomized, controlled trial, comprising cognitively unimpaired participants with a family history of dementia, a body mass index greater than 25, and a suboptimal diet, as determined through a 14-item questionnaire.

604 participants were assigned in a ratio of 1:1 to follow the intervention (MIND-diet group; n=301) or the control diet (control-diet group; n=303) for 3 years. All the participants received counselling regarding adherence to their assigned diet plus support to promote weight loss.

The primary endpoint was the change in a global cognition score and four cognitive domain scores from baseline, all of which were derived from a 12-test battery. From each test, the raw scores were converted to z scores, which were averaged across all tests to create the global cognition score and across component tests to create the four domain scores; higher scores reflect better cognitive performance. The secondary outcome was the change in MRI-derived measures of brain characteristics in a nonrandom sample of participants, from baseline.

The authors reported the following findings:

• The trial was completed by 93.4% of the participants. From baseline to year 3, improvements in global cognition scores were observed in both groups, with increases of 0.205 standardized units in the MIND-diet group and 0.170 standardized units in the control-diet group (mean difference, 0.035 standardized units).
• Changes in white-matter hyperintensities, hippocampal volumes, and total grey- and white-matter volumes on MRI were similar in the two groups.

"Changes in cognition and brain MRI outcomes from baseline to year 3 did not differ significantly between those who followed the MIND diet and those who followed the control diet with mild caloric restriction among cognitively unimpaired participants with a family history of dementia," the researchers concluded.

Reference:

The study titled, "Trial of the MIND Diet for Prevention of Cognitive Decline in Older Persons," was published in The New England Journal of Medicine.

DOI: 10.1056/NEJMoa2302368