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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 5 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, 5 rows. Every row links to its source.
Exposure Question Direction Outcome measured Design People Effect size, as the source reported it Source
Air pollution Environment Prevention Mixed
why

The overall PM2.5 estimate includes no effect (HR 1.04, 95% CI 0.99-1.09). Only the studies that actively assessed everyone for dementia showed a clear effect (HR 1.42, 95% CI 1.00-2.02). Most studies were at high risk of bias.

 Clinically diagnosed dementia meta-analysis not stated PM2.5 HR 1.04 per 2 ug/m3 (95% CI 0.99-1.09) overall; 1.42 (1.00-2.02) with active case ascertainment BMJ 2023
✓ Peer-reviewed PMID 37019461
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
Antihypertensives / BP lowering Medicines Prevention Mixed
why

Antihypertensive treatment improved cognitive scores by a small amount (SMD 0.06, moderate certainty) but the reduction in dementia incidence was not statistically significant (OR 0.89, low certainty). The drug-class rankings rest on one trial per class and are described as highly uncertain.

 Cognitive function scores and incident dementia in hypertensive older adults (four RCTs) meta-analysis 16,823 Antihypertensive treatment significantly improved cognitive function scores (SMD, 0.06; 95% CI, 0.03-0.09; P < .001, GRADE moderate certainty) and showed a nonsignificant trend toward reduced dementia incidence (OR, 0.89; 95% CI, 0.76-1.05; P = .172, GRADE low certainty) Journal of the American Medical Directors Association 2026
✓ Peer-reviewed PMID 41962914
Antihypertensives / BP lowering Medicines Prevention Mixed
why

Antihypertensive use tracked lower Alzheimer's risk but not lower non-Alzheimer dementia risk, where treated and untreated hypertension looked the same. A single baseline blood pressure reading predicted neither.

 Alzheimer's and non-Alzheimer dementia meta-analysis 31,250 Untreated vs treated hypertension: Alzheimer's dementia HR 1.42 (95% CI 1.08-1.87) Neurology 2024
✓ Peer-reviewed PMID 39141884
Metformin / antidiabetic Medicines Prevention Mixed
why

The split inside this one paper is the finding: the 41 observational studies show large benefits (SGLT2i OR 0.56, GLP-1RA OR 0.58) while the 23 randomised trials show no difference. When design and result disagree this cleanly, the trials are the ones to believe.

 Incident dementia meta-analysis 3,462,926 Observational: SGLT2i OR 0.56 (95% CI 0.45-0.69), GLP-1RA OR 0.58 (0.46-0.73) vs non-users; RCTs: no difference Alzheimer's Research & Therapy 2024
✓ Peer-reviewed PMID 39716328

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