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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 11 of 382 rows for Physical activity (general / dose). 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, 11 rows. Every row links to its source.
Exposure	Question	Direction	Outcome measured	Design	People	Effect size, as the source reported it	Source
Physical activity (general / dose) Exercise and activity	Prevention	Mixed why High overall and leisure-time activity were associated with lower dementia risk, but occupational and commuting activity were associated with higher risk. Certainty of evidence was very low to low.	All-cause dementia, Alzheimer's disease and vascular dementia by physical activity domain	meta-analysis	4,227,297	high physical activity levels were associated with reduced risks of all-cause dementia (n=146 effect sizes; RR 0·80 [95% CI 0·75-0·86]; I2=97·4%), Alzheimer's disease (n=59; 0·79 [0·70-0·90]; I2=91·3%), and vascular dementia (n=21; 0·71 [0·58-0·87]; I2=77·5%); however, associations varied by domain. Leisure-time (k=20 studies; n=33 effect sizes; RR 0·76 [95% CI 0·65-0·88]; I2=96·6%) and household (k=1; 0·85 [0·74-0·98]) physical activity were associated with a reduced risk of all-cause dementia. By contrast, occupational (k=5; 1·20 [1·01-1·42]; I2=85·6%) and commuting (k=2; 1·10 [1·03-1·18]; I2=0·0%) physical activity were associated with an increased risk	The Lancet. Public health 2026 ✓ Peer-reviewed PMID 42612650
Physical activity (general / dose) Exercise and activity	Prevention	No effect why No difference between aerobic training and stretching/balance. Cognition was stable in both arms, but with no non-exercising control the trial cannot say whether either arm helped.	ADAS-Cog-Exec 12-month cognitive trajectory	phase 3 trial	296	Between-group cognitive difference -0.078 (SE 0.074, p=0.3); 12-month hippocampal volume loss 0.51% in both arms	Alzheimer's & Dementia 2025 ✓ Peer-reviewed PMID 40271888
Physical activity (general / dose) Exercise and activity	Prevention	No effect why Neither the combined package nor risk-factor modification beat health advice.	ADAS-Cog z-score at 15 months	randomised trial	456	ADAS-Cog z-score difference vs health advice: -0.04 (95% CI -0.34 to 0.26) for combined package	The Lancet Healthy Longevity 2025 ✓ Peer-reviewed PMID 40294622
Physical activity (general / dose) Exercise and activity	Prevention	Benefit why Concentrating activity into one or two days worked about as well as spreading it across the week.	Incident dementia	cohort study	91,512	HR 0.73 (95% CI 0.60-0.89) for >300 min/week concentrated in 1-2 days vs <150 min/week	Journal of Prevention of Alzheimer's Disease 2025 ✓ Peer-reviewed PMID 40514301
Physical activity (general / dose) Exercise and activity	Prevention	Benefit why Direction is for 12 weeks of cycle-ergometer exercise: putative glymphatic influx in the putamen and meningeal lymphatic vessel size and flow increased, and inflammation-related plasma proteins fell in step with the imaging changes. A mechanistic imaging result, not a cognitive outcome.	MRI measures of glymphatic influx and meningeal lymphatic vessel size and flow, and plasma inflammatory proteins, after 12 weeks of cycling in healthy volunteers	cohort study	not stated	not established — pubmed abstract reports no numeric effect size.	Nature Communications 2025 ✓ Peer-reviewed PMID 40204790
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
Physical activity (general / dose) Exercise and activity	Prevention	Benefit why 866 cases over a short follow-up for a disease with a long prodrome, so some of the association may be people already declining moving less.	Incident all-cause dementia over a median 6.9 years	cohort study	78,430	HR 0.49 (95% CI 0.39-0.62) at 9,826 steps/day vs lowest activity	JAMA Neurology 2022 ✓ Peer-reviewed PMID 36066874
Physical activity (general / dose) Exercise and activity	Prevention	Benefit why The largest effect for physical activity anywhere in this table by a wide margin. On 678 cases over 6.3 years, in a disease with a long prodrome, reverse causation is the more likely explanation for an effect that size.	Incident dementia over a median 6.3 years	cohort study	84,854	Trend across MVPA categories HR 0.66 (95% CI 0.62 to 0.70). "The lowest risk was identified in individuals who performed more than 1200 MET/min/week, those who had 84% (95% CI 0.12 to 0.21) lower risk of incident dementia compared to those who performed < 300 MET/min/week."	BMC Medicine 2021 ✓ Peer-reviewed PMID 34852818
Physical activity (general / dose) Exercise and activity	Prevention	No effect why Explicitly finds no neuroprotective effect, and attributes the lower risk seen in other cohorts to reverse causation: activity fell in the nine years before diagnosis. This contradicts the pooled cohort evidence.	Incident dementia; 15-year cognitive decline	cohort study	10,308	HR 1.00 (95% CI 0.80-1.24) for meeting recommended physical activity levels vs not, for dementia risk; no difference in 15-year cognitive decline across activity levels	BMJ 2017 ✓ Peer-reviewed PMID 28642251

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