Adherence to the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet and longitudinal changes in global cognition: a post hoc analysis of the MIND trial.

BACKGROUND

A 3-y randomized trial comparing the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet with a control diet found no significant differences in cognitive outcomes by intervention assignment, potentially due to variability in dietary adherence.

OBJECTIVES

We examined whether adherence to the MIND diet, validated using plasma nutrient biomarkers, was associated with longitudinal changes in global cognition.

METHODS

The MIND trial enrolled 604 community-dwelling adults aged 65 to 84 y without cognitive impairment at baseline. MIND diet adherence was quantified as the change in MIND diet scores from baseline, with higher values indicating greater adherence, and was validated using blood concentrations of antioxidant nutrients, including lutein-zeaxanthin and β-carotene. Participants were classified into categories of no, moderate, or substantial improvement in MIND diet score. Linear mixed-effects models with random intercepts and slopes were used to estimate annual changes in global cognition.

RESULTS

Of 590 participants (mean age: 70.3 y; females: 65%) included in the analysis, 116 (19.7%) showed no improvement, 224 (38.0%) showed modest improvement, and 250 (42.3%) showed substantial improvement in their MIND diet score. Compared with participants with no change in MIND diet score, those with greater improvement (mean absolute increase of 4 points on the 0-14 scale) demonstrated a significant annual increase in global cognitive composite scores [β = 0.035; 95% confidence interval (CI): 0.006, 0.064], along with higher plasma lutein-zeaxanthin (β = 0.088; 95% CI: 0.038, 0.137) and β-carotene (β = 0.075; 95% CI: 0.001, 0.150). Modest improvement was not associated with significant changes in cognitive function. The associations between changes in MIND diet score and cognition were not modified by dietary intervention arm (P for interaction > 0.167).

CONCLUSIONS

Participants with greater increases in MIND diet scores from baseline, indicating higher adherence, showed significant improvements in global cognitive function than those whose scores did not increase during the trial. This study was registered at clinicaltrials.gov as NCT02817074.