MIND Diet Trial
(2015)Objective
To examine whether a newly devised MIND diet score (Mediterranean-DASH Diet Intervention for Neurodegenerative Delay), specifically targeting neuroprotective dietary components, is associated with slower cognitive decline in older adults
Study Summary
• A higher MIND score was positively associated with slower decline in global cognitive score and with each of 5 cognitive domains
• The difference in decline rates for being in the top tertile of MIND diet scores versus the lowest was
equivalent to being 7.5 years younger in age
• MIND diet showed stronger association with cognitive decline than Mediterranean or DASH diets alone
Intervention
Observational assessment of MIND diet score (0-15 points) based on consumption of 10 brain-healthy food groups and avoidance of 5 unhealthy food groups
Inclusion Criteria
Participants of the Rush Memory and Aging Project, free of dementia at enrollment, completed food frequency questionnaires, had at least two cognitive assessments
Study Design
Arms: Tertile 1 (low MIND score, median 6), Tertile 2 (mid MIND score, median 7.5), Tertile 3 (high MIND score, median 9.5)
Patients per Arm: Approximately 320 per tertile (960 total)
Outcome
• Significant associations observed for all 5 cognitive domains, strongest for episodic memory, semantic memory, and perceptual speed
• Results unchanged after adjustment for cardiovascular conditions
Bottom Line
Higher MIND diet scores were significantly associated with slower cognitive decline, with the difference between highest and lowest tertiles equivalent to being 7.5 years younger in age. The MIND diet was more predictive of cognitive preservation than either the Mediterranean or DASH diet alone.
Major Points
- MIND diet score was positively associated with slower global cognitive decline (β=0.0092, p<0.0001)
- Difference in cognitive decline rates between highest and lowest MIND score tertiles equivalent to 7.5 years younger age
- MIND diet showed stronger predictive association than Mediterranean (standardized β 4.39 vs 2.46, p=0.02) or DASH (2.60, p=0.03) diets
- Associations were significant for all 5 cognitive domains: episodic memory, semantic memory, perceptual speed, perceptual organization, and working memory
- Effects persisted after adjustment for cardiovascular conditions (hypertension, stroke, MI, diabetes)
- Excluding 220 participants with MCI at baseline increased the protective estimate by 9.5%
- MIND diet uniquely specifies green leafy vegetables and berries but does not score overall fruit consumption
- Brain-healthy foods include those high in vitamin E, folate, carotenoids, and flavonoids which inhibit β-amyloid deposition
Study Design
- Study Type
- Prospective observational cohort study
- Randomization
- No
- Blinding
- Not applicable (observational study)
- Sample Size
- 960
- Follow-up
- Average 4.7 years (range 2-10 years)
- Centers
- 1
- Countries
- United States
Primary Outcome
Definition: Change in global cognitive score (composite of 19 standardized neuropsychological tests) over time
| Control | Intervention | HR/OR | P-value |
|---|---|---|---|
| - | - | - | <0.0001 |
Limitations & Criticisms
- Observational design cannot establish causation; requires randomized dietary intervention trial for confirmation
- Population was 95% white, 98.5% non-Hispanic, and predominantly female (75%), limiting generalizability
- Population was elderly (mean age 81.4 years), findings may not apply to younger populations
- Limited questionnaire items for some diet components (single items for nuts, berries, beans, olive oil)
- Self-reported diet subject to recall bias, particularly in cognitively impaired adults
- Residual confounding possible despite extensive covariate adjustment
- MIND diet score components selected based on existing literature, not independently validated
- MIND diet correlated with Mediterranean (r=0.62) and DASH (r=0.50) diets, making independent effects difficult to distinguish
Citation
Alzheimers Dement. 2015 September;11(9):1015-1022