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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 14 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, 14 rows. Every row links to its source.
Exposure	Question	Direction	Outcome measured	Design	People	Effect size, as the source reported it	Source
Coffee, tea and flavonoid-rich foods Diet and supplements	Prevention	Benefit why The association was strongest at moderate intake rather than the highest.	Incident dementia over a median 36.8 years	cohort study	131,821	HR 0.82 (95% CI 0.76-0.89) for highest vs lowest quartile of caffeinated coffee	JAMA 2026 ✓ Peer-reviewed PMID 41661604
Coffee, tea and flavonoid-rich foods Diet and supplements	Prevention	Benefit why 882 cases across five quintiles and several interaction strata, so the subgroup estimates rest on small numbers.	Incident dementia over a mean 9.2 years	cohort study	121,986	AHR 0.72 (95% CI 0.57-0.89) for highest vs lowest flavodiet quintile	JAMA Network Open 2024 ✓ Peer-reviewed PMID 39292460
Dietary pattern (general) Diet and supplements	Prevention	Benefit why The association is reported in people who already have elevated Alzheimer's blood markers, which is the point of the study.	Incident dementia over a mean 8.4 years	cohort study	1,865	Dementia HR 0.71 (95% CI 0.58-0.88) per SD of anti-inflammatory diet adherence among participants with elevated p-tau217	JAMA Network Open 2026 ✓ Peer-reviewed PMID 42348207
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 Independent of overall diet quality. Substituting olive oil for margarine or mayonnaise was also associated with lower risk; substituting for butter or other vegetable oils was not.	Dementia-related death over 28 years	cohort study	92,383	HR 0.72 (95% CI 0.64-0.81) for dementia-related death with ≥7 g/day olive oil vs never/rarely	JAMA Network Open 2024 ✓ Peer-reviewed PMID 38709531
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
Dietary pattern (general) Diet and supplements	Prevention	Benefit why Significant on one adherence score (MEDAS, HR 0.77) but not the other (PYRAMID, HR 0.86, 95% CI 0.73-1.02).	Incident dementia over a mean 9.1 years	cohort study	60,298	HR 0.77 (95% CI 0.65-0.91) for highest vs lowest MEDAS tertile	BMC Medicine 2023 ✓ Peer-reviewed PMID 36915130
Dietary pattern (general) Diet and supplements	Prevention	Benefit why Controls declined while the olive-oil arm held steady; the nut arm fell between the two. Cognitive follow-up was available for 334 of 447 enrolled.	Global cognition composite at median 4.1 years	randomised trial	447	Global cognition composite: +0.05 (95% CI -0.11 to 0.21) olive-oil arm vs -0.38 (-0.57 to -0.18) control; P=0.005	JAMA Internal Medicine 2015 ✓ Peer-reviewed PMID 25961184
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
Mediterranean diet Diet and supplements	Prevention	Benefit why Significant on one adherence score (MEDAS, HR 0.77) but not the other (PYRAMID, HR 0.86, 95% CI 0.73-1.02).	Incident dementia over a mean 9.1 years	cohort study	60,298	HR 0.77 (95% CI 0.65-0.91) for highest vs lowest MEDAS tertile	BMC Medicine 2023 ✓ Peer-reviewed PMID 36915130
Mediterranean diet Diet and supplements	Prevention	Benefit why Controls declined while the olive-oil arm held steady; the nut arm fell between the two. Cognitive follow-up was available for 334 of 447 enrolled.	Global cognition composite at median 4.1 years	randomised trial	447	Global cognition composite: +0.05 (95% CI -0.11 to 0.21) olive-oil arm vs -0.38 (-0.57 to -0.18) control; P=0.005	JAMA Internal Medicine 2015 ✓ Peer-reviewed PMID 25961184
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

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