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Moving beyond the prevalent exposure design for causal inference in dementia research
Lachlan Cribb, Margarita Moreno‐Betancur, Zimu Wu, Rory Wolfe, Matthew Paul Pase, Joanne L. Ryan. The Lancet Healthy Longevity, 2025-01-30
Topic: Risk, prevention and care in population studies
As randomised trials are not always feasible or practical, observational studies remain crucial for addressing many causal questions in the dementia prevention field. Through a systematic search, we found that 84 (72%) of the 116 latest observational cohort studies that investigated factors hypothesised to reduce the risk of dementia (hearing aids, physical activity, antihypertensives, antidiabetics, and antidepressants) used a prevalent exposure design. The approach of using a prevalent exposure design, which compares dementia risk between individuals with and without prevalent exposure at the start of follow-up, has several limitations, including ill-defined interventions, selection biases, and challenges in adjusting for confounders. This Personal View discusses these limitations using physical activity as a case study and describes an alternative approach based on the target trial framework that can help to overcome such limitations. This approach aligns observational analyses with the design and analysis principles of randomised trials and can, thereby, improve the robustness and relevance of evidence for dementia prevention, which is the ultimate goal.
Key findings
- Through a systematic search, we found that 84 (72%) of the 116 latest observational cohort studies that investigated factors hypothesised to reduce the risk of dementia (hearing aids, physical activity, antihypertensives, antidiabetics, and antidepressants) used a prevalent exposure design.
Why it matters
This analysis found that most recent observational cohort studies on factors thought to reduce dementia risk used a prevalent exposure design with several limitations. It argues that a target trial framework can improve the robustness of evidence for dementia prevention, but it presents no new treatment results.
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Study details
- Study designcohort study
- Evidence strengthHigh
How this study scored 61/100
Published in a leading specialty journal, and it is a cohort study following people over time. Scored zero for sample size, effect reported, studied in people and randomised / blinded because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 9 / 10 | Tier 2 — leading specialty journal (The Lancet Healthy Longevity) |
| Journal's citation record | 1 / 4 | The Lancet Healthy Longevity: journal h-index 78 (OpenAlex, 2026-10-29) |
| 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 | 4 / 5 | 2025 — within 3 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 | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| 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 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | 3 / 7 | Cited 18 times (OpenAlex, 2026-10-10) |
| Citations per year | 2 / 5 | 6.0 citations a year over 3 year(s) since 2025 |
| Impact for its field and year | 4 / 6 | Cited 15.7× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 2 / 6 | Cited by 3 other studies in this library |
| Still being cited | 2 / 4 | Cited 18 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 3 / 4 | Last-listed author Joanne L. Ryan: h-index 60 (OpenAlex, whole career) |
| Institution's track record | 3 / 3 | Harvard University: institution h-index 3,235 (OpenAlex) |
| Multi-centre collaboration | 2 / 3 | OpenAlex lists 4 institution(s) in 2 countries |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 39894022) |
| Free to read | 2 / 2 | Free to read |
| Total | 61 / 100 | — |
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Read the original
- DOI: 10.1016/j.lanhl.2024.100675
- PubMed: 39894022
- Original source →
- Free full text: The Lancet Healthy Longevity →
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. Check the citation against the original before you use it.
APA 7th
Cribb, L., Moreno‐Betancur, M., Wu, Z., Wolfe, R., Pase, M. P., & Ryan, J. L. (2025). Moving beyond the prevalent exposure design for causal inference in dementia research. The Lancet Healthy Longevity. https://doi.org/10.1016/j.lanhl.2024.100675
Vancouver
Cribb L, Moreno‐Betancur M, Wu Z, Wolfe R, Pase MP, Ryan JL. Moving beyond the prevalent exposure design for causal inference in dementia research. The Lancet Healthy Longevity. 2025. doi:10.1016/j.lanhl.2024.100675. PMID: 39894022.
BibTeX
@article{cribb2025-39894022,
author = {Cribb, Lachlan and Moreno‐Betancur, Margarita and Wu, Zimu and Wolfe, Rory and Pase, Matthew Paul and Ryan, Joanne L.},
title = {{Moving beyond the prevalent exposure design for causal inference in dementia research}},
journal = {The Lancet Healthy Longevity},
year = {2025},
doi = {10.1016/j.lanhl.2024.100675},
pmid = {39894022},
url = {https://doi.org/10.1016/j.lanhl.2024.100675}
}
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