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Newly diagnosed postoperative depression and incident dementia after major surgery: a Korean nationwide retrospective cohort study
Kim J, Kwon EJ, Ahn JH, Cho EA, Shim J, Lee S, Park M, Oh EJ.. Research Square, 2026-09-30
Topic: Health services, long-term care and technology
Background Depression is a potentially modifiable risk factor for dementia in the general population. Whether newly diagnosed postoperative depression is associated with subsequent dementia, and whether this association differs across patient subgroups, has not been well characterised in large surgical populations. Methods This nationwide retrospective cohort study used Korean National Health Insurance Service data on adults undergoing major cardiac or gastrointestinal surgery (2002–2022), excluding those with depression or major neurocognitive or neurological disorders in the preceding 5 years. Postoperative depression was defined as a new depressive disorder diagnosis with at least one antidepressant prescription within 1 year after surgery; those alive and free of dementia at postoperative day 365 entered the landmark analysis. Incident dementia was ascertained during postoperative years 1–6. After 1:3 propensity score matching on age, sex, and income, associations were estimated using Cox proportional hazards regression with sequential adjustment. Results Among 424,637 patients, 7,633 (1.8%) developed postoperative depression. The matched cohort comprised 30,532 patients: 7,633 with postoperative depression and 22,899 without. During follow-up, 786 dementia cases occurred. Postoperative depression was associated with incident dementia (adjusted HR 1.59, 95% CI 1.38–1.85; P < 0.001). The association was stronger in patients aged < 65 years (HR 2.88, 95% CI 1.81–4.58) than ≥ 65 years (HR 1.56, 95% CI 1.34–1.82; P for interaction = 0.005), and persisted when ascertainment was restricted to years 3–6 (HR 1.57, 95% CI 1.29–1.92). Conclusions Newly diagnosed postoperative depression was associated with increased dementia risk, particularly in patients aged < 65 years, supporting prospective evaluation as a potential marker of long-term cognitive risk. Trial registration: Clinical Research Information Service, KCT0012255. Registered 8 July 2026 (retrospectively registered).
Cite this study APA, Vancouver, BibTeX · download .bib or .ris
APA 7th
Kim, J., Kwon, E. J., Ahn, J. H., Cho, E. A., Shim, J., Lee, S., et al. (2026). Newly diagnosed postoperative depression and incident dementia after major surgery: a Korean nationwide retrospective cohort study. Research Square. https://doi.org/10.21203/rs.3.rs-10811216/v1
Vancouver
Kim J, Kwon EJ, Ahn JH, Cho EA, Shim J, Lee S, et al. Newly diagnosed postoperative depression and incident dementia after major surgery: a Korean nationwide retrospective cohort study. Research Square. 2026. doi:10.21203/rs.3.rs-10811216/v1.
BibTeX
@article{kim2026-183d1759,
author = {Kim, J. and Kwon, E. J. and Ahn, J. H. and Cho, E. A. and Shim, J. and Lee, S. and Park, M. and Oh, E. J.},
title = {{Newly diagnosed postoperative depression and incident dementia after major surgery: a Korean nationwide retrospective cohort study}},
journal = {Research Square},
year = {2026},
doi = {10.21203/rs.3.rs-10811216/v1},
url = {https://doi.org/10.21203/rs.3.rs-10811216/v1}
}
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 8 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
- Whether newly diagnosed postoperative depression is associated with subsequent dementia, and whether this association differs across patient subgroups, has not been well characterised in large surgical populations.
- Results Among 424,637 patients, 7,633 (1.8%) developed postoperative depression.
- Postoperative depression was associated with incident dementia (adjusted HR 1.59, 95% CI 1.38–1.85; P < 0.001).
- Conclusions Newly diagnosed postoperative depression was associated with increased dementia risk, particularly in patients aged < 65 years, supporting prospective evaluation as a potential marker of long-term cognitive risk.
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Study details
- Study designcohort study
- Participants424,637
- Effect size1.8%; HR 1.59; HR 2.88
- 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 | 424,637 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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