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Smoking as a risk factor for dementia and cognitive decline: a meta-analysis of prospective studies
Anstey KJ, von Sanden C, Salim A, O'Kearney R.. American journal of epidemiology, 2007-06-14
Topic: Risk, prevention and care in population studies
The authors assessed the association of smoking with dementia and cognitive decline in a meta-analysis of 19 prospective studies with at least 12 months of follow-up. Studies included a total of 26,374 participants followed for dementia for 2-30 years and 17,023 participants followed up for 2-7 years to assess cognitive decline. Mean study age was 74 years. Current smokers at baseline, relative to never smokers, had risks of 1.79 (95% confidence interval (CI): 1.43, 2.23) for incident Alzheimer's disease, 1.78 (95% CI: 1.28, 2.47) for incident vascular dementia, and 1.27 (95% CI: 1.02, 1.60) for any dementia. Compared with those who never smoked, current smokers at baseline also showed greater yearly declines in Mini-Mental State Examination scores over the follow-up period (effect size (beta)=-0.13, 95% CI: -0.18, -0.08). Compared with former smokers, current smokers at baseline showed an increased risk of Alzheimer's disease (relative risk=1.70, 95% CI: 1.25, 2.31) and an increased decline in cognitive abilities (effect size (beta)=-0.07, 95% CI: -0.11, -0.03), but the groups were not different regarding risk of vascular dementia or any dementia. The authors concluded that elderly smokers have increased risks of dementia and cognitive decline.
Key findings
- Compared with those who never smoked, current smokers at baseline also showed greater yearly declines in Mini-Mental State Examination scores over the follow-up period (effect size (beta)=-0.13, 95% CI: -0.18, -0.08).
- Compared with former smokers, current smokers at baseline showed an increased risk of Alzheimer's disease (relative risk=1.70, 95% CI: 1.25, 2.31) and an increased decline in cognitive abilities (effect size (beta)=-0.07, 95% CI: -0.11, -0.03), but the groups were not different regarding risk of vascular dementia or any dementia.
- The authors concluded that elderly smokers have increased risks of dementia and cognitive decline.
Why it matters
This meta-analysis of 19 prospective studies found that current smokers had higher risks of Alzheimer's disease, vascular dementia, and any dementia, and greater yearly declines in Mini-Mental State Examination scores, compared with never smokers. It identifies smoking as a risk factor, not a treatment, cure, or prevention.
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Study details
- Study designmeta-analysis
- Participants26,374
- Evidence strengthHigh
Limitations
These are observational cohort studies, which can show a strong statistical association between smoking and dementia risk but cannot fully rule out that other differences between smokers and non-smokers explain part of the link.
How this study scored 70/100
Published in a peer-reviewed journal, and it is a meta-analysis pooling many studies. Scored zero for effect reported because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (American journal of epidemiology) |
| Journal's citation record | 3 / 4 | American Journal of Epidemiology: journal h-index 416 (OpenAlex, 2026-10-29) |
| Study design | 12 / 12 | A meta-analysis pooling many studies |
| 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 | 1 / 5 | 2007 — within 20 year(s) of the newest study here |
| Sample size | 4 / 4 | 26,374 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 | A review of other studies — randomisation is not credited here |
| Times cited | 6 / 7 | Cited 923 times (OpenAlex, 2026-10-10) |
| Citations per year | 4 / 5 | 44.0 citations a year over 21 year(s) since 2007 |
| Impact for its field and year | 3 / 6 | Cited 5.1× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 4 / 6 | Cited by 52 other studies in this library |
| Still being cited | 3 / 4 | Cited 139 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 2 / 4 | Last-listed author Richard O’Kearney: h-index 35 (OpenAlex, whole career) |
| Institution's track record | 1 / 3 | Australian National University: institution h-index 1,088 (OpenAlex) |
| Multi-centre collaboration | 0 / 3 | OpenAlex lists 1 institution(s) in 1 country — scores zero (affiliation lists can be incomplete) |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 17573335) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Total | 70 / 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. Check the citation against the original before you use it.
APA 7th
Anstey, K. J., von Sanden, C., Salim, A., & O'Kearney, R. (2007). Smoking as a risk factor for dementia and cognitive decline: a meta-analysis of prospective studies. American journal of epidemiology. https://doi.org/10.1093/aje/kwm116
Vancouver
Anstey KJ, von Sanden C, Salim A, O'Kearney R. Smoking as a risk factor for dementia and cognitive decline: a meta-analysis of prospective studies. American journal of epidemiology. 2007. doi:10.1093/aje/kwm116. PMID: 17573335.
BibTeX
@article{anstey2007-17573335,
author = {Anstey, K. J. and von Sanden, C. and Salim, A. and O'Kearney, R.},
title = {{Smoking as a risk factor for dementia and cognitive decline: a meta-analysis of prospective studies}},
journal = {American journal of epidemiology},
year = {2007},
doi = {10.1093/aje/kwm116},
pmid = {17573335},
url = {https://doi.org/10.1093/aje/kwm116}
}
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