Revised Mediterranean Diet Shows No Significant Impact on Cognition, MRI Outcomes in Older Persons

Author(s):

Using a cohort of more than 600 cognitively normal adults, the MIND diet failed to outperform a control diet of mild caloric restriction on several outcomes, including cognition and hippocampal volumes.

Lisa Barnes, PhD

In a randomized, controlled trial (NCT02817074) of older adults without cognitive impairment, findings showed no significant between-group differences in cognition and brain MRI outcomes over a 3-year period for those who followed the MIND diet, a version of the Mediterranean diet, and those on a control diet with mild caloric restriction.

Presented at the 2023 Alzheimer’s Association International Conference (AAIC), held June 16-20, in Netherlands, Amsterdam, the primary end point was change in a global cognition score and 4 cognitive domain scores, all of which were derived from a 12-test battery. After 3 years of treatment, investigators observed 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; 95% CI, –0.022 to 0.092).

Led by Lisa Barnes, PhD, the Alla V. and Solomon Jesmer Professor of Gerontology and Geriatric Medicine at Rush University, a total of 301 and 303 individuals were assigned to the MIND-diet group and the control-diet group, respectively. The MIND diet, or Mediterranean-DASH Intervention for Neurodegenerative Delay, is a hybrid version of the Mediterranean diet and the Dietary Approaches to Stop Hypertension (DASH) diet, with modifications to include foods that have putatively associated with a decreased risk of dementia.

Coming into the trial, participants did not have cognitive impairment but had a family history of dementia, a body mass index greater than 25, and a suboptimal diet, as determined by means of a 14-item questionnaire. Following randomization, all participants received counseling to improve adherence and support to promote weight loss. The raw scores recorded from the global cognition assessment were converted to z scores, which were averaged across all tests to create the global cognition score and across component tests to create the 4 domain scores.

Over the 3-year trial period, 93.4% of participants completed their assigned treatment. In addition to nonsignificant changes seen on the primary end point, the 2 groups showed similar results in changes of white-matter hyperintensities, hippocampal volumes, and total gray- and white-matter volumes on MRI.

In 2015, Barnes and her colleagues at Rush University Medical Center published 2 papers introducing the MIND diet. The first featured 960 participants of the Memory and Aging project who were followed for an average of 4.7 years. In adjusted mixed models, the MIND score was found to be positively associated with slower decline in global cognitive score (ß = 0.0092; P <.0001) and with each of the 5 cognitive domains. The difference in decline rates for being in the top tertile of MIND diet scores vs the lowest was equivalent to being 7.5 years younger in age.²

More recently, in 2022, study findings declared for the first time that the MIND diet intervention can reverse the destructive effects of obesity on cognition and brain structure, with this approach strengthened by a modest calorie restriction. In a cohort of 50 obese women, 37 participants (MIND: n = 22; control: n = 15) completed the 3-month study. Using a comprehensive neuropsychological test battery, patients on the MIND diet had greater improvements in working memory (+1.37; 95% CI, 0.79-1.95) verbal recognition memory (+4.85; 95% CI, 3.30-6.40) and attention (+3.75; 95% CI, 2.43-5.07) than controls (P <.05).

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REFERENCES
1. Barnes LL, Dhana K, Carey VJ, et al. Trial of the MIND diet for prevention of cognitive decline in older persons. Presented at: AAIC 2023; June 16-20; Amsterdam, Netherlands. Abstract
2. Morris MC, Tangney CC, Wang Y, et al. MIND diet slows cognitive decline with aging. Alzheim Dement. 2015;11(9):1015-1022. doi:10.1016/j.jalz.2015.04.011
3. 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. Scientific Reports. 2022;12:2871. doi:10.1038/s41598-021-04258-9