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Declining Incident Dementia Rates Across Four Population-Based Birth Cohorts
Sullivan KJ, Dodge HH, Hughes TF, Chang CH, Zhu X, Liu A, Ganguli M. The Journals of Gerontology: Series A (Biological Sciences and Medical Sciences), 2018-10-12
Topic: Risk, prevention and care in population studies
By pooling two long-running community studies from the same region of Pennsylvania, researchers compared dementia rates across people born in different decades, from the 1900s to the 1940s. Each successively younger birth cohort had a substantially lower risk of developing dementia at a given age, with the youngest group's risk about a quarter of the oldest group's. This adds US evidence, independent of Framingham, that generational health improvements are lowering dementia risk.
Key findings
- Incidence rate ratio fell progressively across birth cohorts, down to 0.233 (95% CI 0.121-0.449) for the 1932-1941 cohort vs the 1902-1911 reference cohort
- Overall 77% relative reduction in dementia incidence comparing the youngest to the oldest birth cohort
- Findings based on 257 incident dementia cases among 3,010 pooled participants from two sequential community cohorts
- Adds an independent US data source (outside Framingham) supporting a generational decline in dementia risk
Why it matters
By pooling two long-running community studies from the same region of Pennsylvania, researchers found that each successively younger birth cohort had a substantially lower risk of developing dementia at a given age, with the youngest group's risk about a quarter of the oldest group's. This adds US evidence, independent of Framingham, that generational health improvements are lowering dementia risk.
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Study details
- Study designcohort
- Participants3,010
- Effect sizeVersus the 1902-1911 birth cohort, incidence rate ratios were 0.655 (95% CI 0.477-0.899) for 1912-1921, 0.387 (95% CI 0.265-0.564) for 1922-1931, and 0.233 (95% CI 0.121-0.449) for 1932-1941 — a 77% relative reduction comparing the youngest to the oldest cohort
- Evidence strengthHigh
Limitations
Drawn from a single, largely white, semi-rural region of southwestern Pennsylvania using two sequentially recruited (not identical) cohorts, limiting generalizability to more diverse or urban populations.
How this study scored 65/100
Published in a peer-reviewed journal, and it is a cohort study following people over time. Scored zero for randomised / blinded and indexed in PubMed 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, still being cited, senior author's track record, institution's track record, multi-centre collaboration and free to read, so those were left out: it earned 40 of the 62 points we could judge it on, which is 65 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (The Journals of Gerontology: Series A (Biological Sciences and Medical Sciences)) |
| 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 | 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 | 3 / 4 | 3,010 participants |
| Effect reported | 3 / 3 | Effect reported with a statistic (interval, p-value, ratio or similar) |
| 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 | — / 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 | 0 / 6 | No other study in this library cites it |
| 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 | 0 / 2 | No PubMed ID and no DOI — scores zero (not stated in the record — scored 0) |
| Free to read | — / 2 | Access not recorded — left out of this score |
| Points | 40 / 62 | Scored on 11 of 20 parts. We have no data for the rest, so they are left out: 40 of the 62 points we could judge it on is 65 out of 100. |
| Total | 65 / 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. This record has no DOI, so the citation leaves it out. Volume, issue and page numbers are not held in the record. The record names 7 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
Sullivan, K. J., Dodge, H. H., Hughes, T. F., Chang, C. H., Zhu, X., Liu, A., et al. (2019). Declining Incident Dementia Rates Across Four Population-Based Birth Cohorts. The Journals of Gerontology: Series A (Biological Sciences and Medical Sciences).
Vancouver
Sullivan KJ, Dodge HH, Hughes TF, Chang CH, Zhu X, Liu A, et al. Declining Incident Dementia Rates Across Four Population-Based Birth Cohorts. The Journals of Gerontology: Series A (Biological Sciences and Medical Sciences). 2019.
BibTeX
@article{sullivan2019-952304d7,
author = {Sullivan, K. J. and Dodge, H. H. and Hughes, T. F. and Chang, C. H. and Zhu, X. and Liu, A. and Ganguli, M.},
title = {{Declining Incident Dementia Rates Across Four Population-Based Birth Cohorts}},
journal = {The Journals of Gerontology: Series A (Biological Sciences and Medical Sciences)},
year = {2019}
}