This page is alzhub.org's plain-English summary of a published study, not the paper itself. It is generated from the record we hold for this study, sourced and linked below — check the original for the full text and methods.

78/100

✓ Peer-reviewed alzhub usefulness score 78 out of 100. Prevention and risk

Topic: Risk, prevention and care in population studies

Objective Physical activity (PA) is associated with a decreased incidence of dementia, but much of the evidence comes from short follow-ups prone to reverse causation. This meta-analysis investigates the effect of study length on the association. Design A systematic review and meta-analysis. Pooled effect sizes, dose-response analysis and funnel plots were used to synthesise the results. Data sources CINAHL (last search 19 October 2021), PsycInfo, Scopus, PubMed, Web of Science (21 October 2021) and SPORTDiscus (26 October 2021). Eligibility criteria Studies of adults with a prospective follow-up of at least 1 year, a valid cognitive measure or cohort in mid-life at baseline and an estimate of the association between baseline PA and follow-up all-cause dementia, Alzheimer's disease or vascular dementia were included (n=58). Results PA was associated with a decreased risk of all-cause dementia (pooled relative risk 0.80, 95% CI 0.77 to 0.84, n=257 983), Alzheimer's disease (0.86, 95% CI 0.80 to 0.93, n=128 261) and vascular dementia (0.79, 95% CI 0.66 to 0.95, n=33 870), even in longer follow-ups (≥20 years) for all-cause dementia and Alzheimer's disease. Neither baseline age, follow-up length nor study quality significantly moderated the associations. Dose-response meta-analyses revealed significant linear, spline and quadratic trends within estimates for all-cause dementia incidence, but only a significant spline trend for Alzheimer's disease. Funnel plots showed possible publication bias for all-cause dementia and Alzheimer's disease. Conclusion PA was associated with lower incidence of all-cause dementia and Alzheimer's disease, even in longer follow-ups, supporting PA as a modifiable protective lifestyle factor, even after reducing the effects of reverse causation.

Key findings

Objective Physical activity (PA) is associated with a decreased incidence of dementia, but much of the evidence comes from short follow-ups prone to reverse causation.
Pooled effect sizes, dose-response analysis and funnel plots were used to synthesise the results.
Results PA was associated with a decreased risk of all-cause dementia (pooled relative risk 0.80, 95% CI 0.77 to 0.84, n=257 983), Alzheimer's disease (0.86, 95% CI 0.80 to 0.93, n=128 261) and vascular dementia (0.79, 95% CI 0.66 to 0.95, n=33 870), even in longer follow-ups (≥20 years) for all-cause dementia and Alzheimer's disease.
Neither baseline age, follow-up length nor study quality significantly moderated the associations.
Dose-response meta-analyses revealed significant linear, spline and quadratic trends within estimates for all-cause dementia incidence, but only a significant spline trend for Alzheimer's disease.

Why it matters

This review of 58 studies found that physical activity was linked to lower risk of dementia and Alzheimer's disease, even in follow-ups of 20 years or more. It is observational, so it cannot prove that exercise prevents dementia.

New to this subject? Start with our plain-English guide: Prevention →

Study details

Study designmeta-analysis
Participants257,983
Effect sizePooled RR 0.80 (95% CI 0.77-0.84) for all-cause dementia
Evidence strengthModerate

Limitations

Observational; mostly self-reported activity; funnel plots suggested publication bias for all-cause dementia and Alzheimer's.

How this study scored 78/100

Published in a peer-reviewed journal, and it is a meta-analysis pooling many studies. We have no data on free to read, so that was left out: it earned 76 of the 98 points we could judge it on, which is 78 out of 100.

Component	Points	Why
Journal tier	7 / 10	Tier 3 — peer-reviewed journal (British Journal of Sports Medicine)
Journal's citation record	3 / 4	British Journal of Sports Medicine: journal h-index 312 (OpenAlex, 2026-10-29)
Study design	12 / 12	A meta-analysis pooling many studies
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	3 / 5	2022 — within 6 year(s) of the newest study here
Sample size	4 / 4	257,983 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	A review of other studies — randomisation is not credited here
Times cited	6 / 7	Cited 418 times (OpenAlex, 2026-10-10)
Citations per year	5 / 5	69.7 citations a year over 6 year(s) since 2022
Impact for its field and year	4 / 6	Cited 17.5× the average for papers of its field and year (OpenAlex FWCI)
Cited by studies here	3 / 6	Cited by 22 other studies in this library
Still being cited	4 / 4	Cited 350 times in 2024–2026 (2026 still in progress; OpenAlex)
Senior author's track record	1 / 4	Last-listed author Katja Linda Waller: h-index 19 (OpenAlex, whole career)
Institution's track record	1 / 3	University of Helsinki: institution h-index 1,201 (OpenAlex)
Multi-centre collaboration	2 / 3	OpenAlex lists 6 institution(s) in 1 country
Indexed in PubMed	2 / 2	Indexed in PubMed (PMID 35301183)
Free to read	— / 2	Access not recorded — left out of this score
Points	76 / 98	Scored on 19 of 20 parts. We have no data for the rest, so they are left out: 76 of the 98 points we could judge it on is 78 out of 100.
Total	78 / 100	—

What each of these 20 components measures, and what this score is not →

Read the original

Full text: free to read — PubMed Central lists this copy as free to read: the link above (checked 10 Oct 2026).

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

Iso-Markku, P., Kujala, U. M., Knittle, K., Polet, J., Vuoksimaa, E., & Waller, K. (2022). Physical activity as a protective factor for dementia and Alzheimer's disease: systematic review, meta-analysis and quality assessment of cohort and case-control studies. British Journal of Sports Medicine. https://doi.org/10.1136/bjsports-2021-104981

Vancouver

Iso-Markku P, Kujala UM, Knittle K, Polet J, Vuoksimaa E, Waller K. Physical activity as a protective factor for dementia and Alzheimer's disease: systematic review, meta-analysis and quality assessment of cohort and case-control studies. British Journal of Sports Medicine. 2022. doi:10.1136/bjsports-2021-104981. PMID: 35301183.

BibTeX

@article{isomarkku2022-35301183,
  author  = {Iso-Markku, P. and Kujala, U. M. and Knittle, K. and Polet, J. and Vuoksimaa, E. and Waller, K.},
  title   = {{Physical activity as a protective factor for dementia and Alzheimer's disease: systematic review, meta-analysis and quality assessment of cohort and case-control studies}},
  journal = {British Journal of Sports Medicine},
  year    = {2022},
  doi     = {10.1136/bjsports-2021-104981},
  pmid    = {35301183},
  url     = {https://doi.org/10.1136/bjsports-2021-104981}
}

Studies this one cites

Referenced by this study and also in the alzhub library, so you can read them here. Showing 12 of 23.

Later studies that cite this one

22 studies in the alzhub library list this one in their references. Showing the 8 highest-scoring.

Related studies in Prevention and risk

Also tagged “biobank”

1,084 studies in the library carry the topic tag “biobank”; these are this study's neighbours in a fixed, alphabetical-by-hash tour of them, not the closest in content. All 1,084 tagged studies.

Similar studies

More on Prevention and risk

See all studies in Prevention and risk →