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Geographical Variation in Dementia
Tom C. Russ, Margaret Gatz, Nancy L. Pedersen, Jean Hannah, Grant M. A. Wyper, George David Batty, Ian J. Deary, John M. Starr. Epidemiology, 2015-01-12
Topic: Risk, prevention and care in population studies
We found a 2- to 3-fold geographical variation in dementia odds in Sweden, after twin random effects-likely to capture genetic and shared environmental variance-were removed. In Scotland, we found no variation in dementia odds in childhood but substantial variation, following a broadly similar pattern to Sweden, by adulthood. There is geographical variation in dementia rates. Most of this variation is likely to result from unshared environmental factors that have their effect in adolescence or later. Further work is required to confirm these findings and identify any potentially modifiable socioenvironmental risk factors for dementia responsible for this geographical variation in risk. However, if these factors do exist and could be optimized in the whole population, our results suggest that dementia rates could be halved.
Key findings
- We found a 2- to 3-fold geographical variation in dementia odds in Sweden, after twin random effects-likely to capture genetic and shared environmental variance-were removed.
- In Scotland, we found no variation in dementia odds in childhood but substantial variation, following a broadly similar pattern to Sweden, by adulthood.
- There is geographical variation in dementia rates.
- Most of this variation is likely to result from unshared environmental factors that have their effect in adolescence or later.
- Further work is required to confirm these findings and identify any potentially modifiable socioenvironmental risk factors for dementia responsible for this geographical variation in risk.
Why it matters
This study found a 2- to 3-fold geographical variation in dementia odds in Sweden after twin random effects were removed, and substantial variation by adulthood in Scotland. It suggests that most of this variation is likely due to unshared environmental factors acting in adolescence or later, and that if these factors could be optimized, dementia rates could be halved.
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Study details
- Participants27,680
- Evidence strengthModerate
How this study scored 54/100
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 (Epidemiology) |
| Journal's citation record | 2 / 4 | Epidemiology: journal h-index 249 (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 | 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 | 1 / 5 | 2015 — within 20 year(s) of the newest study here |
| Sample size | 4 / 4 | 27,680 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 | 4 / 7 | Cited 44 times (OpenAlex, 2026-10-10) |
| Citations per year | 2 / 5 | 3.4 citations a year over 13 year(s) since 2015 |
| Impact for its field and year | 3 / 6 | Cited 3.9× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 2 / 6 | Cited by 5 other studies in this library |
| Still being cited | 1 / 4 | Cited 5 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 4 / 4 | Last-listed author John M. Starr: h-index 111 (OpenAlex, whole career) |
| Institution's track record | 2 / 3 | University College London: institution h-index 2,029 (OpenAlex) |
| Multi-centre collaboration | 2 / 3 | OpenAlex lists 7 institution(s) in 3 countries |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 25575031) |
| Free to read | 2 / 2 | Free to read |
| Total | 54 / 100 | — |
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Read the original
- DOI: 10.1097/ede.0000000000000230
- PubMed: 25575031
- Original source →
- Free full text: Edinburgh Research Explorer (University of Edinburgh) →
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. 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
Russ, T. C., Gatz, M., Pedersen, N. L., Hannah, J., Wyper, G. M. A., Batty, G. D., et al. (2015). Geographical Variation in Dementia. Epidemiology. https://doi.org/10.1097/ede.0000000000000230
Vancouver
Russ TC, Gatz M, Pedersen NL, Hannah J, Wyper GMA, Batty GD, et al. Geographical Variation in Dementia. Epidemiology. 2015. doi:10.1097/ede.0000000000000230. PMID: 25575031.
BibTeX
@article{russ2015-25575031,
author = {Russ, Tom C. and Gatz, Margaret and Pedersen, Nancy L. and Hannah, Jean and Wyper, Grant M. A. and Batty, George David and Deary, Ian J. and Starr, John M.},
title = {{Geographical Variation in Dementia}},
journal = {Epidemiology},
year = {2015},
doi = {10.1097/ede.0000000000000230},
pmid = {25575031},
url = {https://doi.org/10.1097/ede.0000000000000230}
}
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