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Incidence of dementia diagnosis in Denmark, 1986–2023: an age-period-cohort analysis
Julia Callaway, Cosmo Strozza, Óskar Daði Jóhannsson. Social Science & Medicine, 2026-01-08
Topic: Risk, prevention and care in population studies
Denmark is experiencing unprecedented population ageing, highlighting the importance of understanding age-related diseases, including dementia. Dementia is a syndrome characterised by progressive decline in cognitive function that interferes with daily activities and independent living. This study quantifies changes in dementia diagnosis across ages, time periods, and birth cohorts in Denmark. Using Danish registry data from 1986 to 2023, we analysed all individuals aged 50 and older, corresponding to the birth cohorts 1886-1973. We conducted an age-period-cohort analysis and stratified by sex. Dementia diagnosis was measured by either: 1) hospitalisation for dementia via ICD codes; or 2) filling at least two prescriptions for a dementia-related drug. Dementia diagnoses increased with age across cohorts and periods. The age effect showed rates beginning to rise around age 75 and peaking in the late 80s and early 90s. Looking at the period effect, incidence rates begin to increase in 1997 when the first dementia-related drugs became available, followed by a decrease in later years. Younger cohorts showed lower dementia incidence rates compared to older cohorts at similar ages, likely due to changes to modifiable risk factors. Findings from this study contribute to understanding dementia risks on the age, period, and cohort levels, and can inform public health policies aimed at diagnosing cognitive decline and improving quality of life for older populations.
Key findings
- Younger cohorts showed lower dementia incidence rates compared to older cohorts at similar ages, likely due to changes to modifiable risk factors.
Why it matters
This age-period-cohort analysis found that younger cohorts in Denmark showed lower dementia incidence rates compared to older cohorts at similar ages, likely due to changes in modifiable risk factors. It also noted that dementia diagnoses increased with age and that incidence rates began to rise in 1997 when the first dementia-related drugs became available, followed by a decrease in later years.
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Study details
- Evidence strengthModerate
How this study scored 40/100
Published in a peer-reviewed journal. Scored zero for study design, sample size, effect reported, studied in people and randomised / blinded because the record does not state it. We have no data on senior author's track record, so that was left out: it earned 38 of the 96 points we could judge it on, which is 40 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Social Science & Medicine) |
| Journal's citation record | 3 / 4 | Social Science & Medicine: journal h-index 391 (OpenAlex, 2026-10-29) |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| 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 | 5 / 5 | 2026 — within 1 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 | 1 / 7 | Cited 2 times (OpenAlex, 2026-10-10) |
| Citations per year | 1 / 5 | 1.0 citations a year over 2 year(s) since 2026 |
| Impact for its field and year | 4 / 6 | Cited 9.5× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 0 / 6 | No other study in this library cites it |
| Still being cited | 0 / 4 | Cited 2 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | — / 4 | OpenAlex's profile for last-listed author Óskar Daði Jóhannsson holds only 2 work(s), too few to judge a track record — left out of this score |
| Institution's track record | 0 / 3 | University of Southern Denmark: institution h-index 692 (OpenAlex) |
| Multi-centre collaboration | 0 / 3 | OpenAlex lists 1 institution(s) in 1 country — scores zero (affiliation lists can be incomplete) |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 41539062) |
| Free to read | 2 / 2 | Free to read |
| Points | 38 / 96 | Scored on 19 of 20 parts. We have no data for the rest, so they are left out: 38 of the 96 points we could judge it on is 40 out of 100. |
| Total | 40 / 100 | — |
What each of these 20 components measures, and what this score is not →
Read the original
- DOI: 10.1016/j.socscimed.2026.118951
- PubMed: 41539062
- Original source →
- Free full text: Social Science & Medicine →
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
Callaway, J., Strozza, C., & Jóhannsson, Ó. D. (2026). Incidence of dementia diagnosis in Denmark, 1986–2023: an age-period-cohort analysis. Social Science & Medicine. https://doi.org/10.1016/j.socscimed.2026.118951
Vancouver
Callaway J, Strozza C, Jóhannsson ÓD. Incidence of dementia diagnosis in Denmark, 1986–2023: an age-period-cohort analysis. Social Science & Medicine. 2026. doi:10.1016/j.socscimed.2026.118951. PMID: 41539062.
BibTeX
@article{callaway2026-41539062,
author = {Callaway, Julia and Strozza, Cosmo and Jóhannsson, Óskar Daði},
title = {{Incidence of dementia diagnosis in Denmark, 1986–2023: an age-period-cohort analysis}},
journal = {Social Science \& Medicine},
year = {2026},
doi = {10.1016/j.socscimed.2026.118951},
pmid = {41539062},
url = {https://doi.org/10.1016/j.socscimed.2026.118951}
}
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