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Air pollution and dementia using longitudinal electronic health record data from the Indian Health Service
Yachen Zhu, Yuxi Vania Shi, Spero M. Manson, Joan M. O’Connell, Luohua Jiang. Alzheimer s & Dementia, 2022-12-01
Topic: Risk, prevention and care in population studies
Abstract Background Air pollution has been identified as an important risk factor for dementia in previous studies. As a unique population with a history of colonization, American Indians have long been disproportionately affected by air pollution. However, few studies have investigated the effects of air pollution on the risk of developing dementia in American Indians. This study aims to address this important knowledge gap. Method County‐level average air pollution data in 2003‐2007 were downloaded from the land‐use regression models developed by the Center for Air, Climate, & Energy Solutions (CACES) and merged with data from the Indian Health Service (IHS) National Data Warehouse and related electronic health record databases between fiscal year (FY) 2007‐2013. We assigned air pollution exposure to IHS users based on their county of residence and calculated 5‐year averages of PM2.5, O3, CO, and NO2 in each county. A total of 14,910 American Indians who were 65+ years old in FY2007, used IHS services at least once each year, and were dementia free between FY2007‐2009 were included in the main analysis. Cox proportional hazard models with age as the time scale were employed to examine the association of air pollution with dementia incidence, adjusting for potential confounders. Result The PM2.5 levels in the IHS counties were lower than those in all US counties during 2003‐2013, while the levels of other air pollutants were similar to the US (Figure 1). More dementia incident cases were found in IHS counties with higher O3 levels (Figure 2). In multivariable Cox regression models (Table1), we found a significant positive association between dementia and O3 with a hazard ratio (HR) of 1.26 (95% CI: 1.02‐1.55) per 1 ppb standardized O3, while the associations between dementia and PM2.5, and CO were not statistically significant. We found similar results in sensitivity analyses using longer lags between air pollution and dementia or replacing CO by NO2 in the regression model. Conclusion Our study suggests that exposure to O3 is associated with the higher risk of dementia in American Indians. Future efforts to reduce exposure to air pollution might help lower dementia risk in American Indian communities.
Key findings
- Result The PM2.5 levels in the IHS counties were lower than those in all US counties during 2003‐2013, while the levels of other air pollutants were similar to the US (Figure 1).
- In multivariable Cox regression models (Table1), we found a significant positive association between dementia and O3 with a hazard ratio (HR) of 1.26 (95% CI: 1.02‐1.55) per 1 ppb standardized O3, while the associations between dementia and PM2.5, and CO were not statistically significant.
- We found similar results in sensitivity analyses using longer lags between air pollution and dementia or replacing CO by NO2 in the regression model.
- Conclusion Our study suggests that exposure to O3 is associated with the higher risk of dementia in American Indians.
Why it matters
In this study of 14,910 American Indians aged 65 and older, ozone exposure was significantly associated with dementia incidence, while associations with PM2.5 and CO were not statistically significant. The findings concern an environmental risk factor and do not test any treatment, cure, or prevention for Alzheimer's disease.
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Study details
- Participants14,910
- Evidence strengthLow
How this study scored 37/100
Published in a peer-reviewed journal. Scored zero for study design, effect reported and randomised / blinded because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Alzheimer s & Dementia) |
| Journal's citation record | 2 / 4 | Alzheimer s & Dementia: journal h-index 228 (OpenAlex, 2026-10-29) |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 3 / 5 | 2022 — within 6 year(s) of the newest study here |
| Sample size | 4 / 4 | 14,910 participants |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 3 / 3 | Studied in people (participant count stated) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | 0 / 7 | Cited 0 times (OpenAlex, 2026-10-10) |
| Citations per year | 0 / 5 | 0.0 citations a year over 6 year(s) since 2022 |
| Impact for its field and year | 0 / 6 | Cited 0.0× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 0 / 6 | No other study in this library cites it |
| Still being cited | 0 / 4 | Cited 0 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 2 / 4 | Last-listed author Luohua Jiang: h-index 35 (OpenAlex, whole career) |
| Institution's track record | 1 / 3 | University of California, Irvine: institution h-index 1,195 (OpenAlex) |
| Multi-centre collaboration | 1 / 3 | OpenAlex lists 2 institution(s) in 1 country |
| Indexed in PubMed | 1 / 2 | Not in PubMed, but has a DOI |
| Free to read | 2 / 2 | Free to read |
| Total | 37 / 100 | — |
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Read the original
- DOI: 10.1002/alz.067256
- Original source →
- Free full text: eScholarship (California Digital Library) →
Full text: free to read — OpenAlex lists this copy as free to read: the link above (checked 6 Feb 1020).
Cite this study APA, Vancouver, BibTeX · download .bib or .ris
Built from the record alzhub holds for this paper, not looked up. Volume, issue and page numbers are not held in the record. Check the citation against the original before you use it.
APA 7th
Zhu, Y., Shi, Y. V., Manson, S. M., O’Connell, J. M., & Jiang, L. (2022). Air pollution and dementia using longitudinal electronic health record data from the Indian Health Service. Alzheimer s & Dementia. https://doi.org/10.1002/alz.067256
Vancouver
Zhu Y, Shi YV, Manson SM, O’Connell JM, Jiang L. Air pollution and dementia using longitudinal electronic health record data from the Indian Health Service. Alzheimer s & Dementia. 2022. doi:10.1002/alz.067256.
BibTeX
@article{zhu2022-e6610b7d,
author = {Zhu, Yachen and Shi, Yuxi Vania and Manson, Spero M. and O’Connell, Joan M. and Jiang, Luohua},
title = {{Air pollution and dementia using longitudinal electronic health record data from the Indian Health Service}},
journal = {Alzheimer s \& Dementia},
year = {2022},
doi = {10.1002/alz.067256},
url = {https://doi.org/10.1002/alz.067256}
}
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