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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 8 of 382 rows for Modifiable risk factors combined. 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, 8 rows. Every row links to its source.
Exposure	Question	Direction	Outcome measured	Design	People	Effect size, as the source reported it	Source
Modifiable risk factors combined All modifiable factors together	Prevention	Harm why Direction is for carrying the risk factors. The Danish estimate (37.8% across 16 factors) is lower than the Lancet Commission's global 45%.	Population attributable fraction of dementia	cohort study	1,753,515	Overall population attributable fraction 37.8% (95% CI 35.6-40.0); infections 9.4%, depression 8.7%, CVD 7.6%	The Lancet Public Health 2026 ✓ Peer-reviewed PMID 42425116
Modifiable risk factors combined All modifiable factors together	Prevention	Harm why Direction is for carrying the risk factors: depression, diabetes, low education, smoking, obesity, physical inactivity and alcohol overconsumption each independently raised the hazard of early-onset dementia, and most associations were stronger for early-onset than late-onset dementia.	Incident early-onset dementia (before 65) and late-onset dementia over a median 13.7 years	cohort study	544,442	Black versus White race (1·61 [1·23-2·11]), grade school education or less (1·99 [1·67-2·38]), diabetes (2·45 [1·99-3·03]), depression (2·73 [2·34-3·20]), smoking (1·86 [1·56-2·22]), obesity (1·24 [1·04-1·48]), physical inactivity (1·33 [1·11-1·59]), and alcohol overconsumption (1·22 [1·01-1·47]) were independently associated with higher hazards of early-onset dementia	The lancet. Healthy longevity 2026 ✓ Peer-reviewed PMID 41936382
Modifiable risk factors combined All modifiable factors together	Prevention	Harm why Direction is for carrying the risk factors. Which factor mattered most differed by APOE risk group, on 2,065 cases split across 11 factors and three genetic strata, so the subgroup estimates are imprecise.	Incident all-cause dementia over 12.4 years	cohort study	182,473	Low social contact HR 3.86 (95% CI 2.08-7.17) in low APOE risk group; less education PAF 11.35% in high APOE risk group	Annals of Neurology 2025 ✓ Peer-reviewed PMID 41085200
Modifiable risk factors combined All modifiable factors together	Prevention	Harm why Direction is for carrying hypertension, diabetes or smoking. The attributable share rose with the age at which the factors were measured (22% at 45-54, 44% at 65-74), which is what you would expect if some of it is reverse causation rather than cause.	Population attributable fraction of dementia by age 80	cohort study	12,274	22-44% of dementia by age 80 attributable to hypertension, diabetes or smoking	JAMA Neurology 2025 ✓ Peer-reviewed PMID 40455489
Modifiable risk factors combined All modifiable factors together	Prevention	Harm why Direction is for carrying the risk factors: the Commission attributes 45% of cases to 14 modifiable factors, which is the same number read the other way as prevention potential. The Commission's own caveat is that "some associations might be only partly causal".	Population attributable fraction of dementia	systematic review	not stated	"estimated that the PAF for all 14 risk factors was 45.3%" (Table 1: overall PAF 45.3%, rounded 45%); high LDL cholesterol unweighted PAF 18.7%, weighted 6.9%, rounded 7%; untreated vision loss unweighted 6.0%, weighted 2.2%, rounded 2%	The Lancet 2024 ✓ Peer-reviewed PMID 39096926
Modifiable risk factors combined All modifiable factors together	Prevention	Harm why Direction is for carrying the risk factors. 39 candidate factors were screened against 485 cases, so individual estimates are imprecise.	Incident young-onset dementia	cohort study	356,052	485 incident young-onset dementia cases (16.8 per 100,000 person-years) among 356,052 participants; 39 candidate risk factors tested, most of the associated factors modifiable	JAMA Neurology 2024 ✓ Peer-reviewed PMID 38147328
Modifiable risk factors combined All modifiable factors together	Prevention	Harm why Direction is for carrying the risk factors. The weighted combined estimate (32.0% for seven factors) is lower than the Lancet Commission's 45% for 14.	Population attributable fraction of dementia	meta-analysis	not stated	Weighted combined PAF 32.0% (95% CI 26.6-37.5) for seven modifiable factors	Lancet Healthy Longevity 2024 ✓ Peer-reviewed PMID 38824956
Modifiable risk factors combined All modifiable factors together	Prevention	Harm why For the vascular risk factors: up to a quarter of the education-dementia association ran through hypertension, diabetes and related midlife factors, so carrying them accounted for part of the excess risk.	Incident dementia	cohort study	13,368	8-44% lower dementia risk with higher education vs grade school; up to 25% mediated by midlife vascular risk factors	Annals of Neurology 2023 ✓ Peer-reviewed PMID 36966451

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