alzhub.org
Get help now — free helplines

You can call any of these for free. You do not need a diagnosis, an appointment, or a crisis to call — questions and plain exhaustion are reasons enough.

  • Alzheimer's Association 24/7 Helpline 800-272-3900 24 hours a day, 365 days a year Free, confidential support and information for people with dementia, caregivers, families and the public. Master's-level clinicians. Also Spanish.
  • 988 Suicide & Crisis Lifeline 988 24/7 Call or text 988, or chat at 988lifeline.org. For anyone in emotional distress or a mental-health crisis, including caregivers.
  • Alzheimer's Foundation of America (AFA) Helpline 866-232-8484 9:00 am - 9:00 pm ET, seven days a week Licensed social workers providing support, info and referrals. Also text message and web chat. Text: 646-586-5283

In a medical emergency, call 911. More numbers, and what each line does, on the help page.

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

Filter

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
Clear all

Showing 4 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, 4 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 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 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
Blood biomarker test (p-tau217 / amyloid ratio) Care, carers and services Prevention Benefit
why

Direction is for the test's accuracy against the reference standard; an accuracy result, not a health outcome. Stand-alone plasma p-tau217 gave 81% accuracy and 79% PPV; confirming positives with PET or CSF raised both to 91% while cutting PET scans needed to find 100 amyloid-positive people from 536 to 124. Immunoassays matched mass spectrometry on PPV but had lower accuracy.

 Accuracy and positive predictive value for amyloid positivity (CSF or PET) in cognitively unimpaired people, stand-alone and in a two-step workflow cross-sectional study 2,916 As a stand-alone test, plasma p-tau217 achieved a positive predictive value (PPV) of 79% (95% CI, 74-84) and an overall accuracy of 81% (95% CI, 80-82). In a 2-step workflow, the PPV and accuracy significantly increased to 91% (95% CI, 86-95). While this approach required screening of 677 individuals with plasma p-tau217 to identify 100 Aβ-positive individuals, compared to 536 participants when using PET alone, it reduced the need for PET testing to 124 JAMA Neurology 2025
✓ Peer-reviewed PMID 40952756

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