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68/100

✓ Peer-reviewed alzhub usefulness score 68 out of 100. Risk factors

Topic: Air pollution and environmental exposures

Plain-language summary

We report 1,136 cases of incident dementia among 4,166 individuals with nonmissing APOE status. Mean [mean ± standard deviation (SD)] 10-y average PM2.5 was 10.1 (±2.9) μg/m3. Each 1-μg/m3 increase in the moving average of 10-y PM2.5 was associated with a 16% greater hazard of all-cause dementia [1.16 (95% confidence interval: 1.03, 1.31)]. Results using calendar time as the time axis were similar. In this prospective cohort study with extensive exposure data and consensus-based outcome ascertainment, elevated long-term exposure to PM2.5 was associated with increased hazard of all-cause dementia. We found that optimal control of age and time confounding could be achieved through use of either age or calendar time as the time axis in our study. Our results strengthen evidence on the neurodegenerative effects of PM2.5. https://doi.org/10.1289/EHP9018.

Cite this study APA, Vancouver, BibTeX · download .bib or .ris

APA 7th

Shaffer, R. M., Blanco, M. N., Li, G., Adar, S. D., Carone, M., Szpiro, A. A., et al. (2021). Fine Particulate Matter and Dementia Incidence in the Adult Changes in Thought Study. Environmental health perspectives. https://doi.org/10.1289/ehp9018

Vancouver

Shaffer RM, Blanco MN, Li G, Adar SD, Carone M, Szpiro AA, et al. Fine Particulate Matter and Dementia Incidence in the Adult Changes in Thought Study. Environmental health perspectives. 2021. doi:10.1289/ehp9018. PMID: 34347531.

BibTeX

@article{shaffer2021-34347531,
  author  = {Shaffer, Rachel M and Blanco, Magali N and Li, Ge and Adar, Sara D and Carone, Marco and Szpiro, Adam A and Kaufman, Joel D and Larson, Timothy V and others},
  title   = {{Fine Particulate Matter and Dementia Incidence in the Adult Changes in Thought Study}},
  journal = {Environmental health perspectives},
  year    = {2021},
  doi     = {10.1289/ehp9018},
  pmid    = {34347531},
  url     = {https://doi.org/10.1289/ehp9018}
}

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How to read this study

Design: this is a follow-up (cohort) study. People are observed over time and not assigned to anything, so an association can reflect other differences between groups. Look at how long follow-up lasted, how many dropped out, and whether the authors adjusted for age, education and other health conditions.
Size: the record lists 4,166 participants. Ask whether that is enough for the question, and who they were.
Effect: the record gives no effect size, so the summary above cannot say how large any difference was.

What the evidence grade means here

This page is graded moderate. alzhub.org assigns the grade automatically from keywords in the abstract, not from reading the paper. Moderate means the abstract mentions a cohort, case-control or longitudinal design. It can add at most 5 of the 100 points in the study score, and it is a label about design, not a verdict on whether the findings are true.

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Key findings

We report 1,136 cases of incident dementia among 4,166 individuals with nonmissing APOE status.
Mean [mean ± standard deviation (SD)] 10-y average PM2.5 was 10.1 (±2.9) μg/m3.
Each 1-μg/m3 increase in the moving average of 10-y PM2.5 was associated with a 16% greater hazard of all-cause dementia [1.16 (95% confidence interval: 1.03, 1.31)].
Results using calendar time as the time axis were similar.
In this prospective cohort study with extensive exposure data and consensus-based outcome ascertainment, elevated long-term exposure to PM2.5 was associated with increased hazard of all-cause dementia.

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Study details

Study designcohort study
Participants4,166
Evidence strengthModerate

How this study scored 68/100

Published in a peer-reviewed journal, and it is a cohort study following people over time. Scored zero for effect reported and randomized / blinded 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, multicenter collaboration and free to read, so those were left out: it earned 38 of the 56 points we could judge it on, which is 68 out of 100.

Component	Points	Why
Journal tier	7 / 10	Tier 3 — peer-reviewed journal (Environmental health perspectives)
Journal's citation record	— / 4	No journal record from OpenAlex — left out of this score
Study design	7 / 12	A cohort study following people over time
Strength of evidence	3 / 5	Rated “moderate” in our summary
Peer-review validation	10 / 10	Peer-reviewed. Published as an article in a named peer-reviewed journal.
How recent	3 / 5	2021 — within 6 year(s) of the newest study here
Sample size	3 / 4	4,166 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)
Randomized / blinded	0 / 2	No randomization or blinding stated — scores zero (not stated in the record — scored 0)
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
Multicenter collaboration	— / 3	Institutions not listed — left out of this score
Indexed in PubMed	2 / 2	Indexed in PubMed (PMID 34347531)
Free to read	— / 2	Access not recorded — left out of this score
Points	38 / 56	Scored on 10 of 20 parts. We have no data for the rest, so they are left out: 38 of the 56 points we could judge it on is 68 out of 100.
Total	68 / 100	—

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