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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 5 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, 5 rows. Every row links to its source.
Exposure	Question	Direction	Outcome measured	Design	People	Effect size, as the source reported it	Source
Birth cohort and calendar period (secular trend in dementia) All modifiable factors together	Prevention	Benefit why Direction is for more recent birth cohort: after controlling for age and period, later-born cohorts were less likely to have dementia in all three regions, more so among women; the point estimates for men in England were not significant.	Age-specific dementia prevalence by birth cohort in the US, Europe and England	cross-sectional study	62,437	point estimate for 1944-1948 vs 1919-1923 cohorts: US, -0.55 [95% CI, -0.77 to -0.34] vs -0.18 [95% CI, -0.25 to -0.10]; Europe, -1.49 [95% CI, -1.72 to -1.27] vs -0.24 [95% CI, -0.35 to -0.13]; and England, -0.48 [95% CI, -0.89 to -0.08] vs -0.23 [95% CI, -0.38 to -0.07]	JAMA Network Open 2025 ✓ Peer-reviewed PMID 40455442
Birth cohort and calendar period (secular trend in dementia) All modifiable factors together	Prevention	Benefit why Direction is for later birth cohort: each successive cohort had a significantly lower incident dementia rate, independent of sex, education and age.	Incident dementia rate by decade of birth (1902-1941)	cohort study	3,010	Compared to the earliest birth cohort (1902-1911), each subsequent cohort had a significantly lower incident dementia rate (1912-1921: incidence rate ratio [IRR] = 0.655, 95% confidence interval [95% CI] = 0.477-0.899; 1922-1931: IRR = 0.387, 95% CI = 0.265-0.564; 1932-1941: IRR = 0.233, 95% CI = 0.121-0.449)	The Journals of Gerontology: Series A (Biological Sciences and Medical Sciences) 2019 ✓ Peer-reviewed PMID 30312371
Birth cohort and calendar period (secular trend in dementia) All modifiable factors together	Prevention	Benefit why Direction is for the later survey year: prevalence fell from 11.6% to 8.8%, with rising education associated with some of the decline despite a worse cardiovascular risk profile.	Dementia prevalence among US adults 65+, 2000 versus 2012	cross-sectional study	21,057	Dementia prevalence among those 65 years or older decreased from 11.6% (95% CI, 10.7%-12.7%) in 2000 to 8.8% (95% CI, 8.2%-9.4%) (8.6% with age- and sex-standardization) in 2012 (P < .001)	JAMA Internal Medicine 2017 ✓ Peer-reviewed PMID 27893041
Birth cohort and calendar period (secular trend in dementia) All modifiable factors together	Prevention	Benefit why Direction is for later calendar epoch: incidence fell 44% from the first to the fourth epoch, but only among people with at least a high school diploma. The authors could not fully explain the decline.	5-year incidence of dementia across four epochs (late 1970s to early 2010s)	cohort study	5,205	The 5-year age- and sex-adjusted cumulative hazard rates for dementia were 3.6 per 100 persons during the first epoch (late 1970s and early 1980s), 2.8 per 100 persons during the second epoch (late 1980s and early 1990s), 2.2 per 100 persons during the third epoch (late 1990s and early 2000s), and 2.0 per 100 persons during the fourth epoch (late 2000s and early 2010s). Relative to the incidence during the first epoch, the incidence declined by 22%, 38%, and 44% during the second, third, and fourth epochs, respectively. This risk reduction was observed only among persons who had at least a high school diploma (hazard ratio, 0.77; 95% confidence interval, 0.67 to 0.88)	New England Journal of Medicine 2016 ✓ Peer-reviewed PMID 26863354
Birth cohort and calendar period (secular trend in dementia) All modifiable factors together	Prevention	Benefit why Direction is for the later-born population: prevalence was 6.5% against the 8.3% expected from the earlier study (odds ratio 0.7), which the authors read as a cohort effect.	Dementia prevalence at age 65+ in three English areas, CFAS II (2008-11) versus CFAS I (1989-94)	cross-sectional study	15,431	Using CFAS I age and sex specific estimates of prevalence in individuals aged 65 years or older, standardised to the 2011 population, 8·3% (884,000) of this population would be expected to have dementia in 2011. However, CFAS II shows that the prevalence is lower (6·5%; 670,000), a decrease of 1·8% (odds ratio for CFAS II vs CFAS I 0·7, 95% CI 0·6-0·9, p=0·003)	The Lancet 2013 ✓ Peer-reviewed PMID 23871492

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