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Association between urban green space coverage and incident Alzheimer’s disease among older adults in metropolitan South Korea: a population-based retrospective cohort study
Lee H, Cho Y, Park SJ, Kang JH, Chung J, Yu J, Park YJ, Seo D et al.. Research Square, 2026-09-14
Topic: Air pollution and environmental exposures
Background Urban green space (UGS) may support cognitive health in later life, but longitudinal evidence from rapidly aging Asian cities remains limited. We examined the association between officially designated UGS coverage and incident Alzheimer's disease (AD) among older adults in metropolitan South Korea. Methods This population-based retrospective cohort study used the Korean National Health Insurance Service database linked to health screening data. We included 95,822 adults aged 65 years or older residing in seven metropolitan areas who underwent health screening in 2009–2010. UGS coverage in 2010 was defined as the proportion of officially designated parks and open green spaces within each residential district and categorized into quartiles. Participants were followed from January 1, 2011, until incident AD, death, or December 31, 2023. Cox proportional hazards models estimated adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs). Results During follow-up, 21,733 incident AD cases occurred, with incidence rates of 24.71, 21.04, 19.14, and 22.17 per 1,000 person-years across Q1–Q4. In the fully adjusted model, higher UGS coverage was associated with modestly lower AD risk (aHR 0.96 [95% CI, 0.92–0.999] for Q2, 0.90 [0.86–0.94] for Q3, and 0.94 [0.90–0.97] for Q4; P for trend < 0.001). Conclusions Higher UGS coverage was associated with a lower risk of incident AD among older adults in urban South Korea. These findings support further investigation of urban green infrastructure as a potentially modifiable environmental factor for cognitive health in aging populations.
Key findings
- Results During follow-up, 21,733 incident AD cases occurred, with incidence rates of 24.71, 21.04, 19.14, and 22.17 per 1,000 person-years across Q1–Q4.
- In the fully adjusted model, higher UGS coverage was associated with modestly lower AD risk (aHR 0.96 [95% CI, 0.92–0.999] for Q2, 0.90 [0.86–0.94] for Q3, and 0.94 [0.90–0.97] for Q4; P for trend < 0.001).
- Conclusions Higher UGS coverage was associated with a lower risk of incident AD among older adults in urban South Korea.
- These findings support further investigation of urban green infrastructure as a potentially modifiable environmental factor for cognitive health in aging populations.
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Study details
- Study designcohort study
- Participants95,822
- Effect sizeaHR 0.96
- Evidence strengthModerate
How this study scored 16/100
Preprint — not yet peer-reviewed. It scored 52 on the same rubric, but non-peer-reviewed sources are capped at 16, so it shows as 16. Scored zero for randomised / blinded because the record does not state it. We have no data on times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record, institution's track record and multi-centre collaboration, so those were left out: it earned 32 of the 62 points we could judge it on, which is 52 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 2 / 10 | Tier 4 — not a peer-reviewed journal (Research Square) |
| Journal's citation record | 0 / 4 | Not a journal article, so the journal's record does not count |
| Study design | 7 / 12 | A cohort study following people over time |
| Strength of evidence | 3 / 5 | Rated “moderate” in our summary |
| Peer-review validation | 4 / 10 | Preprint — not yet peer-reviewed. Hosted on a preprint server. |
| How recent | 5 / 5 | 2026 — within 1 year(s) of the newest study here |
| Sample size | 4 / 4 | 95,822 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 | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| 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 | 1 / 2 | Not in PubMed, but has a DOI |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Points | 32 / 62 | Scored on 12 of 20 parts. We have no data for the rest, so they are left out: 32 of the 62 points we could judge it on is 52 out of 100. |
| Total | 52 / 100 | Capped to 16 because this is not a peer-reviewed article. |
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APA 7th
Lee, H., Cho, Y., Park, S. J., Kang, J. H., Chung, J., Yu, J., et al. (2026). Association between urban green space coverage and incident Alzheimer’s disease among older adults in metropolitan South Korea: a population-based retrospective cohort study. Research Square. https://doi.org/10.21203/rs.3.rs-10506133/v1
Vancouver
Lee H, Cho Y, Park SJ, Kang JH, Chung J, Yu J, et al. Association between urban green space coverage and incident Alzheimer’s disease among older adults in metropolitan South Korea: a population-based retrospective cohort study. Research Square. 2026. doi:10.21203/rs.3.rs-10506133/v1.
BibTeX
@article{lee2026-e65dac19,
author = {Lee, H. and Cho, Y. and Park, S. J. and Kang, J. H. and Chung, J. and Yu, J. and Park, Y. J. and Seo, D. and others},
title = {{Association between urban green space coverage and incident Alzheimer’s disease among older adults in metropolitan South Korea: a population-based retrospective cohort study}},
journal = {Research Square},
year = {2026},
doi = {10.21203/rs.3.rs-10506133/v1},
url = {https://doi.org/10.21203/rs.3.rs-10506133/v1}
}