A total of 20 studies were included in the systematic review, and 17 provided data for the meta-analysis. 5 key findings →
Design: systematic review Participants: 20 Evidence: high
Full summary, score breakdown and related studies → Original source
Research
27,380 Alzheimer's and dementia studies in plain English, each scored out of 100.
Regarding exposures to air pollution, there was convincing (class I) evidence for the association between long-term exposure to solvents and a higher incidence of dementia or cognitive impairment (odds ratio, OR=1.139), and highly suggestive (class II) evidence for the association between long-term exposure to some pollutants and higher risk for cognitive disorders (higher incidence of dementia with high vs. low levels of carbon monoxide, CO: OR=1.587; higher incidence of vascular dementia per 1 μg/m 3 increase of nitrogen oxides, NO x : hazard ratio, HR=1.004). 1 key finding →
Design: systematic review Participants: 195 Evidence: high
Full summary, score breakdown and related studies → Original source
Among 2 184 847 Danish citizens aged between 65 and 95 years, there were 3024 individuals with DLB (mean [SD] age, 78 [6], 1894 [62.6%] male) and 3808 with PDD (mean [SD] age, 78 [6], 2400 [63.0%] male) who were matched with 30 240 and 38 080 controls, respectively. 5 key findings →
Design: case-control study Participants: 3,024 Evidence: moderate
Full summary, score breakdown and related studies → Original source
Among 27 857 participants (mean [SD] age at baseline, 61 [10] years; 15 747 female participants [56.5%]; 19 249 non-Hispanic White participants [69.1%]), 4105 (14.7%) developed dementia during the follow-up period (mean [SD], 10.2 [5.6] years). 5 key findings →
Design: cohort study Participants: 857 Evidence: moderate
Full summary, score breakdown and related studies → Original source
Evidence suggests that lifelong cumulative exposure to pesticides may generate lasting toxic effects on the central nervous system and contribute to the development of Alzheimer's disease (AD). 3 key findings →
Design: meta-analysis Evidence: high
Full summary, score breakdown and related studies → Original source
71/100
We have found evidence of a positive association between residential levels of air pollution across London and being diagnosed with dementia, which is unexplained by known confounding factors. 3 key findings →
Design: cohort study Participants: 978 Evidence: moderate
Full summary, score breakdown and related studies → Original source
Air pollution is a modifiable and preventable factor, and it is a possible risk factor for dementia. 4 key findings →
Design: systematic review Evidence: high
Full summary, score breakdown and related studies → Original source
10-year average (SD) PM2.5 from death across the autopsy cohort was 8.2 (1.9) μg/m3. 5 key findings →
Design: cohort study Participants: 832 Evidence: moderate
Full summary, score breakdown and related studies → Original source
71/100
During the follow-up period, we identified a total of 617 incident neurodegenerative diseases, 301 PD and 182 AD. 5 key findings →
Design: prospective cohort Participants: 617 Evidence: moderate
Full summary, score breakdown and related studies → Original source
71/100
In total, 42 eligible studies were included. 5 key findings →
Design: meta-analysis Evidence: high
Full summary, score breakdown and related studies → Original source
We identified 1,041 incident all-cause dementia cases in 4,283 participants over 37,102 person-years of follow-up. 5 key findings →
Design: cohort study Participants: 4,283 Evidence: moderate
Full summary, score breakdown and related studies → Original source
Among 5,699 participants (mean age: 70±8 years), we observed total PM2.5 concentrations ranging from 16 to 206 μg/m3. 5 key findings →
Design: longitudinal study Participants: 5,699 Evidence: moderate
Full summary, score breakdown and related studies → Original source
70/100
Evidence on the association between air pollution and dementia is accumulating but still inconclusive, and the potential effect modification by genetics is unclear. 2 key findings →
Design: cohort study Participants: 227,840 Evidence: moderate
Full summary, score breakdown and related studies → Original source
70/100
In total, 20 articles were selected for review; 18 included results on the long-term effects of PM2.5 on dementia, 13 on AD, and eight on VaD. 5 key findings →
Design: systematic review Evidence: high
Full summary, score breakdown and related studies → Original source
Several studies with animal research associate air pollution in Alzheimer's disease (AD) neuropathology, but the actual impact of air pollution on the risk of AD is unknown. 3 key findings →
Design: cohort study Participants: 95,690 Evidence: moderate
Full summary, score breakdown and related studies → Original source
An emerging body of evidence has raised concern regarding the potentially harmful effects of inhaled pollutants on the central nervous system during the last decade. 2 key findings →
Design: systematic review Evidence: high
Full summary, score breakdown and related studies → Original source
In this cohort study, higher residential PM2.5 levels, especially from agriculture and wildfires, were associated with higher rates of incident dementia, providing further evidence supporting PM2.5 reduction as a population-based approach to promote healthy cognitive aging. 5 key findings →
Design: cohort study Participants: 27 Evidence: moderate
Full summary, score breakdown and related studies → Original source
Based on 19 studies the weighted RR for occupational exposure to EMFs was 1.26 (95% confidence interval (CI) 1.07⁻1.50) for ALS, 1.33 (95% CI 1.07⁻1.64) for Alzheimer's disease and 1.02 (95% CI 0.83⁻1.26) for Parkinson's disease. 5 key findings →
Design: meta-analysis Evidence: high
Full summary, score breakdown and related studies → Original source
We found no evidence that exposure to road traffic noise, either independently or in combination with traffic air pollution, was associated with risk of dementia in our study area. 5 key findings →
Design: longitudinal study Participants: 1,721 Evidence: moderate
Full summary, score breakdown and related studies → Original source
We report 1,136 cases of incident dementia among 4,166 individuals with nonmissing APOE status. 5 key findings →
Design: cohort study Participants: 4,166 Evidence: moderate
Full summary, score breakdown and related studies → Original source
68/100
At study entry, the mean (SD) age of the participants was 70 (SD, 8.9) years and 41% were males. 5 key findings →
Design: longitudinal study Participants: 555 Evidence: moderate
Full summary, score breakdown and related studies → Original source
In the first year of follow-up, increased exposure to all air pollutants was associated with an increase in the use of CMHTs in a dose-response manner. 5 key findings →
Design: longitudinal study Participants: 5,024 Evidence: moderate
Full summary, score breakdown and related studies → Original source
A health impact assessment (HIA) is an important tool for making informed decisions regarding the design and evaluation of environmental interventions. 5 key findings →
Design: meta-analysis Evidence: high
Full summary, score breakdown and related studies → Original source
68/100
This study included 5646 participants (mean age 76 years, 65% female). 5 key findings →
Design: longitudinal study Participants: 5,646 Evidence: moderate
Full summary, score breakdown and related studies → Original source
Both environmental exposures and genetics are known to play important roles in shaping human aging. 5 key findings →
Participants: 492,567 Evidence: low
Full summary, score breakdown and related studies → Original source
Where “Free full text” comes from
Free full text links and the Full text may need a subscription label come from Unpaywall, Europe PMC and OpenAlex records of free copies, checked 10 Oct 2026. A study with neither is unknown, not paywalled. Show only studies that are free to read
How the 0–100 score works — and why some entries are capped
This is alzhub's own score. It is not an official metric, not an impact factor, and no journal, publisher or ranking body endorses it. We built it so that a reader who is not a scientist can tell a landmark trial from a conference abstract without having to already know the difference. Every point comes from one of 20 components, all of them printed on the study itself, so you can disagree with our arithmetic rather than having to trust the total.
- Journal tier up to 10 pts
- Journal's citation record up to 4 pts
- Study design up to 12 pts
- Strength of evidence up to 5 pts
- Peer-review validation up to 10 pts
- How recent up to 5 pts
- Sample size up to 4 pts
- Effect reported up to 3 pts
- Studied in people up to 3 pts
- Randomised / blinded up to 2 pts
- Times cited up to 7 pts
- Citations per year up to 5 pts
- Impact for its field and year up to 6 pts
- Cited by studies here up to 6 pts
- Still being cited up to 4 pts
- Senior author's track record up to 4 pts
- Institution's track record up to 3 pts
- Multi-centre collaboration up to 3 pts
- Indexed in PubMed up to 2 pts
- Free to read up to 2 pts
Journals are placed in ordered tiers, never given a numeric impact factor — we could not verify current impact factors from a source we control, and an invented one would be worse than none. Tier 1 is the top-tier general journals (NEJM, The Lancet, JAMA, Nature, Science, Nature Medicine); tier 2 is the leading specialty journals; tier 3 is every other peer-reviewed journal. A separate part scores how much the journal's own papers are cited, which tells the tier-3 journals apart.
Two rules we don't bend. First, we never fill in a missing value: if a record does not state a sample size or a design, that component scores zero, and if we simply have no data for a part, such as a citation count, that part is left out and the study is scored on the parts we could check. The study card says which. Second, anything that is not a peer-reviewed article is capped at 16/100 and carries a warning chip — so a conference abstract or a company press release can never outrank a peer-reviewed paper, no matter how good it looks.
We rank a rigorous null result — a good trial showing that something does not work — above an early positive finding. Someone deciding whether to buy a supplement is served by that, and the rigour is already counted by the design and journal components.
The score is computed from the published data alone and is reproducible: the same file always yields the same numbers.
See the whole rubric drawn out → — four charts covering all 27,380 studies: how the scores are spread and where the cap bites, which of the 20 components the library is strong and weak on, which subjects rest on stronger evidence, and what kinds of study each subject is actually built from.
What this library is — and isn't
This is a large sample of the Alzheimer's literature, not an exhaustive index of it. It holds 27,380 records, built mostly from automated pulls of Europe PMC (60.6% of the library) and OpenAlex (18.6%), plus smaller pulls from PubMed, Crossref and medRxiv. If a study, a drug, or a finding isn't here, that is not evidence it doesn't exist in the literature — it may simply not have been pulled in yet.
1,032 records (3.8% of the library) are not peer-reviewed — 962 of those are preprints posted before any journal review, and the rest are conference abstracts, regulatory notices and reports. Every study card on this page states its status plainly, and the score above is capped for anything that isn't a peer-reviewed article.
See the full, machine-readable breakdown of this library's coverage →