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 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
Herpes zoster / shingles vaccination Infection and vaccination Prevention Benefit New dementia diagnoses over 5.5 years cohort study 232,124 -2.0 percentage points (95% CI -3.5 to -0.4) absolute reduction in new dementia diagnoses over 5.5 years The Lancet Neurology 2026
✓ Peer-reviewed PMID 41579903
Herpes zoster / shingles vaccination Infection and vaccination Prevention Benefit
why

Regression discontinuity across a birth-date eligibility threshold, which makes confounding by health-seeking behaviour less likely than in a plain cohort comparison. Eligibility did not change uptake of other preventive services or other chronic-disease diagnoses, which is the check that makes the design convincing.

 New dementia diagnoses over 7.4 years cohort study 101,219 "eligibility for HZ vaccination (ie, being born shortly after vs shortly before November 2, 1936) decreased the probability of receiving a new dementia diagnosis during 7.4 years by 1.8 percentage points (95% CI, 0.4-3.3 percentage points; P = .01)"; vaccination uptake rose 16.4 percentage points (95% CI 13.2-19.5) across the threshold JAMA 2025
✓ Peer-reviewed PMID 40267506
Herpes zoster / shingles vaccination Infection and vaccination Prevention Benefit
why

Regression discontinuity across the 2 September 1933 eligibility threshold; stronger in women than men.

 Probability of a new dementia diagnosis over 7 years cohort study not stated -3.5 percentage points (95% CI 0.6 to 7.1, P = 0.019) in 7-year dementia diagnosis probability; 20.0% relative reduction (95% CI 6.5-33.4) Nature 2025
✓ Peer-reviewed PMID 40175543
Other vaccination (influenza, pneumococcal, general) Infection and vaccination Prevention Benefit
why

Pooled observational studies, so open to the confounding the natural-experiment studies were designed to avoid.

 Any dementia meta-analysis 104,031,186 Influenza vaccination RR 0.87 (95% CI 0.77-0.99) for any dementia; pneumococcal vaccination RR 0.64 (95% CI 0.47-0.87) for Alzheimer's disease Age and Ageing 2025
✓ Peer-reviewed PMID 41269248
Severe (hospital-treated) infection Infection and vaccination Prevention Harm
why

Direction is for a hospital-treated infection: the raised dementia hazard (1.54) was barely attenuated by adjustment for frailty (1.49) and persisted among non-frail participants (1.34), so pre-existing frailty and comorbidity did not explain it.

 Incident dementia after a 5-year exposure window and 2-year washout, adjusted for frailty and comorbidity cohort study 449,223 Adjustment for frailty resulted in no statistically significant attenuation of the infection and dementia association (adjusted hazard ratio [HR] 1·54 [95% CI 1·43-1·67] for presence vs absence of severe infections before adjustment for frailty and 1·49 [1·37-1·61] after adjustment). The association was also evident within a subgroup of non-frail participants (1·34 [1·18-1·53]) The lancet. Healthy longevity 2026
✓ Peer-reviewed PMID 41969011

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