Every finding in the evidence table: 382 rows, filterable

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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 6 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, 6 rows. Every row links to its source.
Exposure	Question	Direction	Outcome measured	Design	People	Effect size, as the source reported it	Source
Depression Sleep, mood and social life	Prevention	Harm why The authors read these symptoms as early markers of neurodegeneration rather than causes — which is also how an earlier analysis of this same cohort read its own null result for midlife depression.	Incident dementia over a mean 22.6 years	cohort study	5,811	HR 1.29-1.51 for six specific midlife depressive symptoms	Lancet Psychiatry 2026 ✓ Peer-reviewed PMID 41412145
Depression Sleep, mood and social life	Prevention	Harm why Direction is for having depression (51% higher risk). Treated depression carried lower risk than untreated (HR 0.7), which is the more interesting half but is an observational comparison of people who did and did not get treatment.	Incident dementia	cohort study	354,313	Depression treatment HR 0.7 (95% CI 0.62-0.77) for incident dementia vs untreated depression	Biological Psychiatry 2023 ✓ Peer-reviewed PMID 36526487
Genetic risk disclosure Sleep, mood and social life	Prevention	Harm why Distress rose, and rose most in APOE4 homozygotes. The authors nonetheless conclude disclosure by a trained provider was generally safe and well tolerated in this psychologically pre-screened group.	Disease-specific distress 2-7 days after disclosure	cohort study	9,496	Disease-specific distress change at 2-7 days: +2.25 (homozygotes) vs +0.53 (heterozygotes) vs +0.79 (non-carriers)	The Lancet Healthy Longevity 2025 ✓ Peer-reviewed PMID 41319675
Sleep Sleep, mood and social life	Prevention	Harm why Direction is for LOSING slow-wave sleep. 52 cases in 346 people, so the estimate is imprecise, and slow-wave sleep also falls with Alzheimer's genetic risk, which muddies cause and effect.	Incident dementia over 17 years	cohort study	346	HR 1.27 (95% CI 1.06-1.54) per 1%/year loss of slow-wave sleep	JAMA Neurology 2023 ✓ Peer-reviewed PMID 37902739
Sleep Sleep, mood and social life	Prevention	Harm why Direction is for SHORT sleep (6 hours or less): higher dementia risk than a 7-hour sleep duration.	Incident dementia over 25 years	cohort study	7,959	HR ~1.22 (age 50) and ~1.37 (age 60) for short vs. 7-hour sleep; persistent short sleep across ages 50/60/70 ~30% higher risk	Nature Communications 2021 ✓ Peer-reviewed PMID 33879784
Social isolation / loneliness Sleep, mood and social life	Prevention	Harm why Isolation (being alone) carried the risk (HR 1.26); loneliness (feeling alone) did not once depressive symptoms were accounted for (HR 1.04, 95% CI 0.94-1.16). That split matters, and the loneliness meta-analysis here reaches the opposite conclusion about loneliness.	Incident dementia over a mean 11.7 years	cohort study	462,619	Social isolation HR 1.26 (95% CI 1.15-1.37) for incident dementia	Neurology 2022 ✓ Peer-reviewed PMID 35676089

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