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Home › Research › What the research found › Every row

Every row of the evidence table

One row per finding: what was tested, which way the result went, and how the study was built. The answer by area, and where the studies disagree, are on the main page.

Every row

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Area All 382 Care, carers and services 140 Medicines 85 Genes (not modifiable) 35 All modifiable factors together 27 Diet and supplements 23 Exercise and activity 21 Sleep, mood and social life 19 Hearing and vision 8 Alcohol, tobacco and cannabis 6 Infection and vaccination 5 Heart and metabolic health 4 Injury, delirium and falls 4 Environment 3 Cognitive activity 2
Question Both Prevention 190 Treatment 192
Direction Any Benefit 144 Harm 105 No effect 38 Mixed 37 No direction reported 58
Design Any meta-analysis 57 randomised trial 44 phase 3 trial 15 systematic review 9 phase 2 trial 10 cohort study 136 phase 1 trial 2 cross-sectional study 31 case-control study 14 modelling study 20 regulatory decision 7 company announcement 1 coverage determination 1 None 35
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Showing 7 of 382 rows. One row per study per exposure: a study that tested two different things appears twice, once for each.

Scroll the table sideways to see every column.

Research and outcomes, 7 rows. Every row links to its source.
Exposure Question Direction Outcome measured Design People Effect size, as the source reported it Source
Dietary pattern (general) Diet and supplements Prevention Benefit
why

Direction is for a healthier plant-based diet: higher overall and healthful plant-based diet scores were associated with lower dementia risk, while a higher unhealthful plant-based diet score was associated with higher risk (pooled HR 1.42).

 Incident dementia by plant-based diet index (overall, healthful and unhealthful) meta-analysis 207,981 higher scores in PDI and hPDI were associated with lower risk of dementia (highest vs. lowest tertile: pooled HR for PDI = 0.70, 95% CI, 0.53-0.92, p for trend <0.001; pooled HR for hPDI = 0.71, 0.48-1.06, p for trend = 0.03) ... higher uPDI was associated with higher dementia risk (highest vs. lowest tertile: pooled HR = 1.42, 1.19-1.70, p for trend <0.001). In the meta-analysis, individuals in the highest hPDI tertile had 21% lower dementia risk, and those in the highest uPDI tertile had 24% higher risk The journal of prevention of Alzheimer's disease 2026
✓ Peer-reviewed PMID 41564649
Dietary pattern (general) Diet and supplements Prevention Benefit
why

Pooled observational studies only.

 Dementia and Alzheimer's disease meta-analysis 65,955 Pooled OR 0.89 (95% CI 0.84-0.94) for dementia; cohort HR 0.84 (0.76-0.94); Alzheimer's OR 0.73 (0.62-0.85) Aging Clinical and Experimental Research 2024
✓ Peer-reviewed PMID 38519775
Dietary pattern (general) Diet and supplements Prevention Benefit
why

Observational. Points the opposite way to the randomised MIND diet trial.

 Incident dementia meta-analysis 224,049 HR 0.83 per 3-point MIND-score increment (95% CI 0.72-0.95); highest vs lowest tertile HR 0.83 (0.76-0.90) JAMA Psychiatry 2023
✓ Peer-reviewed PMID 37133875
MIND diet Diet and supplements Prevention Benefit
why

Observational. Points the opposite way to the randomised MIND diet trial.

 Incident dementia meta-analysis 224,049 HR 0.83 per 3-point MIND-score increment (95% CI 0.72-0.95); highest vs lowest tertile HR 0.83 (0.76-0.90) JAMA Psychiatry 2023
✓ Peer-reviewed PMID 37133875
Mediterranean diet Diet and supplements Prevention Benefit
why

Pooled observational studies only.

 Dementia and Alzheimer's disease meta-analysis 65,955 Pooled OR 0.89 (95% CI 0.84-0.94) for dementia; cohort HR 0.84 (0.76-0.94); Alzheimer's OR 0.73 (0.62-0.85) Aging Clinical and Experimental Research 2024
✓ Peer-reviewed PMID 38519775
Omega-3 / fish and fish oil Diet and supplements Prevention Benefit
why

Dietary intake and blood levels, pooled from observational cohorts. The much larger supplement estimate (HR 0.36) comes from one cohort's self-selected supplement users, not from a trial.

 All-cause dementia or cognitive decline meta-analysis 103,651 Dietary DHA intake RR 0.82 for dementia or cognitive decline; ADNI supplement users HR 0.36 (95% CI 0.18-0.72) for Alzheimer's American Journal of Clinical Nutrition 2023
✓ Peer-reviewed PMID 37028557
Ultra-processed food Diet and supplements Prevention Harm
why

Heterogeneity was extreme (I-squared 97%), so the pooled figure hides large differences between the 10 studies.

 Dementia meta-analysis 867,316 Pooled RR 1.44 (95% CI 1.09-1.90) for high vs low ultra-processed food intake Journal of Neurology 2024
✓ Peer-reviewed PMID 37831127

How this table was built, and where it is weak →