Every finding in the evidence table: 382 rows, filterable

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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

Showing 18 of 382 rows. One row per study per exposure: a study that tested two different things appears twice, once for each.

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Research and outcomes, 18 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
Physical activity (general / dose) Exercise and activity	Prevention	Benefit why The authors call the association weak (RR 0.97), and it was absent beyond 10 years of follow-up.	Cognitive impairment or decline	meta-analysis	341,471	Pooled RR 0.97 (95% CI 0.97-0.99) for cognitive impairment/decline; no association beyond 10 years of follow-up	JAMA Network Open 2024 ✓ Peer-reviewed PMID 38300618
Physical activity (general / dose) Exercise and activity	Prevention	Benefit why Pooled across 29 cohorts. The association weakened to HR 0.85 after maximal confounder adjustment and was not significant for low-intensity activity.	Incident Alzheimer's disease	meta-analysis	2,068,519	Pooled HR 0.72 (95% CI 0.65-0.80) overall; HR 0.85 (95% CI 0.79-0.91) after maximal confounder adjustment; high-intensity activity HR 0.56 (95% CI 0.45-0.68); moderate-intensity HR 0.85 (95% CI 0.80-0.93); low-intensity HR 0.94 (95% CI 0.77-1.15, not significant)	Ageing Research Reviews 2023 ✓ Peer-reviewed PMID 37979700
Physical activity (general / dose) Exercise and activity	Prevention	Benefit why The authors state the association held in longer follow-ups, which is their answer to the reverse-causation objection raised by the Whitehall II cohort.	Incident all-cause dementia and Alzheimer's disease	meta-analysis	257,983	Pooled RR 0.80 (95% CI 0.77-0.84) for all-cause dementia	British Journal of Sports Medicine 2022 ✓ Peer-reviewed PMID 35301183
Resistance training Exercise and activity	Prevention	Benefit why Seven small trials; working memory did not improve (P=0.14).	General cognitive function and executive function	meta-analysis	not stated	General cognition SMD 0.53 (P=0.04); executive function SMD 0.50 (P=0.0003)	International Journal of Sports Medicine 2020 ✓ Peer-reviewed PMID 32599643
Hearing loss / hearing aids Hearing and vision	Prevention	Benefit why Mostly observational (25 of 31 studies), so people who take up hearing aids may differ from those who do not. The authors call for randomised trials — and ACHIEVE, the trial that followed, was null overall.	Long-term cognitive decline	meta-analysis	137,484	HR 0.81 (95% CI 0.76-0.87) for cognitive decline with hearing aid use	JAMA Neurology 2023 ✓ Peer-reviewed PMID 36469314
Vision impairment / cataract surgery Hearing and vision	Prevention	Benefit why Against untreated cataract. People who had surgery ended up at about the same risk as controls who never had cataracts (HR 0.84, 95% CI 0.66-1.06), and there was no short-term gain in those already cognitively impaired.	Long-term cognitive decline / dementia	meta-analysis	558,276	HR 0.75 (95% CI 0.72-0.78) for cognitive decline with surgery	Ophthalmology 2024 ✓ Peer-reviewed PMID 38336283
Other vaccination (influenza, pneumococcal, general) Infection and vaccination	Prevention	Benefit why Pooled observational studies, so open to the confounding the natural-experiment studies were designed to avoid.	Any dementia	meta-analysis	104,031,186	Influenza vaccination RR 0.87 (95% CI 0.77-0.99) for any dementia; pneumococcal vaccination RR 0.64 (95% CI 0.47-0.87) for Alzheimer's disease	Age and Ageing 2025 ✓ Peer-reviewed PMID 41269248
Antihypertensives / BP lowering Medicines	Prevention	Benefit why Individual participant data from five double-blind placebo-controlled trials, which is the strongest design in this table for this exposure.	Incident dementia over a median 4.3 years	meta-analysis	28,008	Adjusted OR 0.87 (95% CI 0.75-0.99) for incident dementia	European Heart Journal 2022 ✓ Peer-reviewed PMID 36282295
Antihypertensives / BP lowering Medicines	Prevention	Benefit why Consistent across 14 trials (I-squared 0%) but small in absolute terms: 0.39 percentage points over about 4 years.	Incident dementia or cognitive impairment	meta-analysis	96,158	OR 0.93 (95% CI 0.88-0.98); absolute risk reduction 0.39% over 4.1 years	JAMA 2020 ✓ Peer-reviewed PMID 32427305
Metformin / antidiabetic Medicines	Prevention	Benefit why Heterogeneity was near-total (I-squared 98.9%) and the estimate went to null in people newly diagnosed with diabetes (HR 1.01), which is where prevalent-user bias would be smallest.	Incident dementia	meta-analysis	3,463,100	HR 0.76 (95% CI 0.65-0.91) vs non-users overall; HR 1.01 (0.81-1.27) in newly diagnosed diabetes	Diabetes, Obesity and Metabolism 2025 ✓ Peer-reviewed PMID 39780315
Education / cognitive reserve Sleep, mood and social life	Prevention	Benefit why Education and job complexity each contributed independently; about 28% of the education effect ran through occupation.	Dementia-free survival time	meta-analysis	10,195	Education and occupational complexity independently associated with longer dementia-free survival (28% of education effect mediated by occupation)	Journal of Alzheimer's Disease 2022 ✓ Peer-reviewed PMID 34776437
Education / cognitive reserve Sleep, mood and social life	Prevention	Benefit why Effect held over and above measured Alzheimer's pathology, which is the point of the reserve idea.	Incident MCI or dementia	meta-analysis	not stated	"High CR was related to a 47% reduced relative risk of MCI or dementia (pooled-hazard ratio: 0.53 [0.35, 0.81]), with residual-based CR reducing risk by 62% and proxy-based CR by 48%."	Neuropsychology Review 2021 ✓ Peer-reviewed PMID 33415533

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