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Fine particulate matter is a potential determinant of Alzheimer's disease: A systemic review and meta-analysis
Tsai TL, Lin YT, Hwang BF, Nakayama SF, Tsai CH, Sun XL, Ma C, Jung CR.. Environmental research, 2019-08-08
Topic: Air pollution and environmental exposures
Air pollution is a modifiable and preventable factor, and it is a possible risk factor for dementia. However, evidence from epidemiological studies is still limited. We conducted a systematic review and meta-analysis to summarize the epidemiological evidence for long-term effects of particulate matter with an aerodynamic diameter ≤2.5 μm (PM 2.5 ) on dementia/Alzheimer's disease (AD). Our inclusion criteria for eligible studies were: longitudinal cohort study design, no overlap in study population, age of study subject ≥50 years, detailed description of exposure assessment for PM 2.5 , outdoor assessment of exposure to PM 2.5 , usage of a clear definition of dementia/AD, and accessibility of sufficient information for meta-analysis. Six databases were searched for eligible studies. The random-effect model was used to synthesize the associations between PM 2.5 and dementia. After exclusion of all irrelevant studies, we analyzed the results of four cohort studies conducted in Canada, Taiwan, the UK, and the US during 2015-2018 among more than 12 million elderly subjects aged ≥50 years (N = 12,119,853). Our meta-analysis reveals that exposure to a 10 μg/m 3 increase in PM 2.5 was significantly and positively associated with dementia (pooled HR = 3.26, 95% CI: 1.20, 5.31). In subgroup analyses, exposure to a 10 μg/m 3 increase in PM 2.5 was found to be positively associated with AD (pooled HR = 4.82, 95% CI: 2.28, 7.36). Analysis of current epidemiological research on PM 2.5 and dementia confirmed that exposure to PM 2.5 was positively associated with a higher risk for dementia. However, it is to be noted that the included studies mainly relied on claim-based diagnosis and showed large differences in methods of exposure assessment, hence further epidemiological studies with well validated outcomes and with standardized exposure assessment models are required to ascertain the relationship between PM 2.5 and dementia/AD.
Key findings
- After exclusion of all irrelevant studies, we analyzed the results of four cohort studies conducted in Canada, Taiwan, the UK, and the US during 2015-2018 among more than 12 million elderly subjects aged ≥50 years (N = 12,119,853).
- Our meta-analysis reveals that exposure to a 10 μg/m 3 increase in PM 2.5 was significantly and positively associated with dementia (pooled HR = 3.26, 95% CI: 1.20, 5.31).
- In subgroup analyses, exposure to a 10 μg/m 3 increase in PM 2.5 was found to be positively associated with AD (pooled HR = 4.82, 95% CI: 2.28, 7.36).
- Analysis of current epidemiological research on PM 2.5 and dementia confirmed that exposure to PM 2.5 was positively associated with a higher risk for dementia.
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Study details
- Study designsystematic review
- Effect sizeHR = 3.26; HR = 4.82
- Evidence strengthHigh
How this study scored 71/100
Published in a peer-reviewed journal, and it is a systematic review of all the studies on the question. Scored zero for sample size and studied in people because the record does not state it. We have no data on journal's citation record, times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record, institution's track record and multi-centre collaboration, so those were left out: it earned 41 of the 58 points we could judge it on, which is 71 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Environmental research) |
| Journal's citation record | — / 4 | No journal record from OpenAlex — left out of this score |
| Study design | 12 / 12 | A systematic review of all the studies on the question |
| Strength of evidence | 5 / 5 | Rated “high” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 2 / 5 | 2019 — within 10 year(s) of the newest study here |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 3 / 3 | Effect reported with a statistic (interval, p-value, ratio or similar) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | A review of other studies — randomisation is not credited here |
| Times cited | — / 7 | No citation count (not found in OpenAlex) — left out of this score |
| Citations per year | — / 5 | No citation count or no year — left out of this score |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| Still being cited | — / 4 | No yearly citation counts — left out of this score |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | — / 3 | Institutions not listed — left out of this score |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 31421449) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Points | 41 / 58 | Scored on 11 of 20 parts. We have no data for the rest, so they are left out: 41 of the 58 points we could judge it on is 71 out of 100. |
| Total | 71 / 100 | — |
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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. The record names 8 authors; APA and Vancouver show the first six, BibTeX and the downloads carry all of them. Check the citation against the original before you use it.
APA 7th
Tsai, T. L., Lin, Y. T., Hwang, B. F., Nakayama, S. F., Tsai, C. H., Sun, X. L., et al. (2019). Fine particulate matter is a potential determinant of Alzheimer's disease: A systemic review and meta-analysis. Environmental research. https://doi.org/10.1016/j.envres.2019.108638
Vancouver
Tsai TL, Lin YT, Hwang BF, Nakayama SF, Tsai CH, Sun XL, et al. Fine particulate matter is a potential determinant of Alzheimer's disease: A systemic review and meta-analysis. Environmental research. 2019. doi:10.1016/j.envres.2019.108638. PMID: 31421449.
BibTeX
@article{tsai2019-31421449,
author = {Tsai, T. L. and Lin, Y. T. and Hwang, B. F. and Nakayama, S. F. and Tsai, C. H. and Sun, X. L. and Ma, C. and Jung, C. R.},
title = {{Fine particulate matter is a potential determinant of Alzheimer's disease: A systemic review and meta-analysis}},
journal = {Environmental research},
year = {2019},
doi = {10.1016/j.envres.2019.108638},
pmid = {31421449},
url = {https://doi.org/10.1016/j.envres.2019.108638}
}
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