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Physical activity, cognitive decline, and risk of dementia: 28 year follow-up of Whitehall II cohort study
Sabia S, Dugravot A, Dartigues JF, Abell J, Elbaz A, Kivimäki M, Singh-Manoux A. BMJ, 2017-06-22
Topic: Risk, prevention and care in population studies
This unusually long 28-year study found no evidence that being physically active in midlife protects against dementia later in life. Physical activity levels only dropped in the final years before a dementia diagnosis, suggesting that lower activity is an early symptom of undiagnosed brain disease rather than a cause of it (reverse causation), challenging some earlier positive findings.
Cite this study APA, Vancouver, BibTeX · download .bib or .ris
APA 7th
Sabia, S., Dugravot, A., Dartigues, J. F., Abell, J., Elbaz, A., Kivimäki, M., et al. (2017). Physical activity, cognitive decline, and risk of dementia: 28 year follow-up of Whitehall II cohort study. BMJ. https://doi.org/10.1136/bmj.j2709
Vancouver
Sabia S, Dugravot A, Dartigues JF, Abell J, Elbaz A, Kivimäki M, et al. Physical activity, cognitive decline, and risk of dementia: 28 year follow-up of Whitehall II cohort study. BMJ. 2017. doi:10.1136/bmj.j2709. PMID: 28642251.
BibTeX
@article{sabia2017-9e3f2420,
author = {Sabia, S. and Dugravot, A. and Dartigues, J. F. and Abell, J. and Elbaz, A. and Kivimäki, M. and Singh-Manoux, A.},
title = {{Physical activity, cognitive decline, and risk of dementia: 28 year follow-up of Whitehall II cohort study}},
journal = {BMJ},
year = {2017},
doi = {10.1136/bmj.j2709},
pmid = {28642251},
url = {https://doi.org/10.1136/bmj.j2709}
}
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 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.
Key findings
- Among 10,308 people followed 27 years on average, meeting physical activity guidelines was not linked to lower dementia risk (HR 1.00)
- There was no difference in the rate of cognitive decline across activity levels over 15 years of repeated testing
- Physical activity only started declining an average of 9 years before dementia diagnosis, not earlier
- Authors conclude previous studies showing a protective effect may reflect reverse causation rather than a true causal benefit
Why it matters
Meeting physical activity guidelines was not linked to lower dementia risk, and activity only declined in the years just before diagnosis, suggesting lower activity is an early symptom rather than a cause. This null result challenges the idea that midlife exercise protects against dementia.
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Study details
- Study designcohort
- Participants10,308
- Effect sizeHR 1.00 (95% CI 0.80-1.24) for meeting recommended physical activity levels vs not, for dementia risk; no difference in 15-year cognitive decline across activity levels
- Evidence strengthNull-result
Limitations
Relies on self-reported physical activity, prone to recall and measurement error; single UK occupational cohort of civil servants, not necessarily representative of the general population; cannot fully separate reverse causation from residual confounding.
How this study scored 70/100
Published in a leading specialty journal, and it is a cohort study following people over time. Scored zero for 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, still being cited, senior author's track record, institution's track record and multicenter collaboration, so those were left out: it earned 45 of the 64 points we could judge it on, which is 70 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 9 / 10 | Tier 2 — leading specialty journal (BMJ) |
| 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 “null-result” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 2 / 5 | 2017 — within 10 year(s) of the newest study here |
| Sample size | 4 / 4 | 10,308 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) |
| 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 | 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 |
| Multicenter collaboration | — / 3 | Institutions not listed — left out of this score |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 28642251) |
| Free to read | 2 / 2 | Free to read |
| Points | 45 / 64 | Scored on 12 of 20 parts. We have no data for the rest, so they are left out: 45 of the 64 points we could judge it on is 70 out of 100. |
| Total | 70 / 100 | — |
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