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The incidence of dementia: a meta-analysis
Jorm AF, Jolley D.. Neurology, 1998-09-01
Topic: Risk, prevention and care in population studies
Objective To carry out a meta-analysis of the age-specific incidence of all dementias, including AD and vascular dementia. Background Several meta-analyses have been carried out on dementia prevalence, but none on its incidence. Methods We used loess-curve fitting to analyze data from 23 published studies reporting age-specific incidence data. Results The incidence of both dementia and AD rose exponentially up to the age of 90 years, with no sign of leveling off. The incidence rates for vascular dementia varied greatly from study to study, but the trend was also for an exponential rise with age. There was no sex difference in dementia incidence (p = 0.21), but women tended to have a higher incidence of AD in very old age, and men tended to have a higher incidence of vascular dementia at younger ages. East Asian countries had a lower incidence of dementia than Europe (p = 0.0004), and also tended to have a lower incidence of AD. Conclusions The incidence of dementia rises exponentially to the age of 90 years. Any sex differences are small, and incidence is lower in East Asia than in Europe.
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APA 7th
Jorm, A. F., & Jolley, D. (1998). The incidence of dementia: a meta-analysis. Neurology. https://doi.org/10.1212/wnl.51.3.728
Vancouver
Jorm AF, Jolley D. The incidence of dementia: a meta-analysis. Neurology. 1998. doi:10.1212/wnl.51.3.728. PMID: 9748017.
BibTeX
@article{jorm1998-9748017,
author = {Jorm, A. F. and Jolley, D.},
title = {{The incidence of dementia: a meta-analysis}},
journal = {Neurology},
year = {1998},
doi = {10.1212/wnl.51.3.728},
pmid = {9748017},
url = {https://doi.org/10.1212/wnl.51.3.728}
}
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Key findings
- Results The incidence of both dementia and AD rose exponentially up to the age of 90 years, with no sign of leveling off.
Why it matters
This 1998 meta-analysis pooled 23 published studies and found that new cases of dementia and Alzheimer's disease rose exponentially with age up to 90, 'with no sign of leveling off.' It found no overall difference between women and men (p = 0.21), and a lower dementia incidence in East Asian countries than in Europe (p = 0.0004). It describes how often dementia appears at different ages and in different regions; it does not explain why, and it does not test any treatment or prevention.
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Study details
- Study designmeta-analysis
- Evidence strengthHigh
How this study scored 68/100
Published in a leading specialty journal, and it is a meta-analysis pooling many studies. Scored zero for sample size, effect reported and studied in people because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 9 / 10 | Tier 2 — leading specialty journal (Neurology) |
| Journal's citation record | 4 / 4 | Neurology: journal h-index 525 (OpenAlex, 2026-10-29) |
| Study design | 12 / 12 | A meta-analysis pooling many studies |
| Strength of evidence | 5 / 5 | Rated “high” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 1 / 5 | 1998 — older than 20 years, still counted |
| 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 | A review of other studies — randomisation is not credited here |
| Times cited | 6 / 7 | Cited 886 times (OpenAlex, 2026-10-10) |
| Citations per year | 4 / 5 | 29.5 citations a year over 30 year(s) since 1998 |
| Impact for its field and year | 4 / 6 | Cited 15.5× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 4 / 6 | Cited by 49 other studies in this library |
| Still being cited | 3 / 4 | Cited 59 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 2 / 4 | Last-listed author David J Jolley: h-index 34 (OpenAlex, whole career) |
| Institution's track record | 1 / 3 | The University of Melbourne: institution h-index 1,342 (OpenAlex) |
| Multi-centre collaboration | 1 / 3 | OpenAlex lists 3 institution(s) in 1 country |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 9748017) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Total | 68 / 100 | — |
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