Home › Research › Prevention and risk
Potentially modifiable risk factors for dementia in identical twins
Gatz M, Mortimer JA, Fratiglioni L, Johansson B, Berg S, Reynolds CA, Pedersen NL.. Alzheimer's & dementia : the journal of the Alzheimer's Association, 2006-04-01
Topic: Risk, prevention and care in population studies
Background The purpose of this study was to test nongenetic factors that might explain discordance for dementia in monozygotic twin pairs. Risk factors included education, engaged lifestyle in midlife, and early life circumstances indexed by tooth loss, short adult height, and parental social class. Methods Data are from the HARMONY study, including members of the Swedish Twin Registry age 65 and older and alive in 1998, who were screened and assessed clinically for dementia. Analyses included a case-control design to evaluate the risk factors and a co-twin control design that permits testing nongenetic risk factors while controlling for genetic influences. Case-control analyses included 310 dementia cases and 3,063 nondemented controls. There were 106 monozygotic twin pairs discordant for dementia. Risk factors were assessed independently by the Swedish Twin Registry three decades previously. Results Case-control findings showed that history of tooth loss before age 35 and low educational attainment were significant risk factors for Alzheimer's disease, with short adult height also contributing to risk for total dementia. In co-twin control analyses, only history of tooth loss before age 35 was a significant risk factor for Alzheimer's disease, whereas low educational attainment also contributed to risk for total dementia and lack of physical exercise to risk for non-Alzheimer's dementias. Conclusions Potentially modifiable risk factors from early and midlife, with a cumulative detrimental effect on the brain, contribute to risk of dementia. Based on the association with tooth loss, further investigation of inflammatory load as a risk factor for Alzheimer's disease is warranted.
Cite this study APA, Vancouver, BibTeX · download .bib or .ris
APA 7th
Gatz, M., Mortimer, J. A., Fratiglioni, L., Johansson, B., Berg, S., Reynolds, C. A., et al. (2006). Potentially modifiable risk factors for dementia in identical twins. Alzheimer's & dementia : the journal of the Alzheimer's Association. https://doi.org/10.1016/j.jalz.2006.01.002
Vancouver
Gatz M, Mortimer JA, Fratiglioni L, Johansson B, Berg S, Reynolds CA, et al. Potentially modifiable risk factors for dementia in identical twins. Alzheimer's & dementia : the journal of the Alzheimer's Association. 2006. doi:10.1016/j.jalz.2006.01.002. PMID: 19595867.
BibTeX
@article{gatz2006-19595867,
author = {Gatz, M. and Mortimer, J. A. and Fratiglioni, L. and Johansson, B. and Berg, S. and Reynolds, C. A. and Pedersen, N. L.},
title = {{Potentially modifiable risk factors for dementia in identical twins}},
journal = {Alzheimer's \& dementia : the journal of the Alzheimer's Association},
year = {2006},
doi = {10.1016/j.jalz.2006.01.002},
pmid = {19595867},
url = {https://doi.org/10.1016/j.jalz.2006.01.002}
}
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 7 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
- Results Case-control findings showed that history of tooth loss before age 35 and low educational attainment were significant risk factors for Alzheimer's disease, with short adult height also contributing to risk for total dementia.
- In co-twin control analyses, only history of tooth loss before age 35 was a significant risk factor for Alzheimer's disease, whereas low educational attainment also contributed to risk for total dementia and lack of physical exercise to risk for non-Alzheimer's dementias.
Why it matters
In this twin study, a history of tooth loss before age 35 was a significant risk factor for Alzheimer's disease even in co-twin analyses controlling for genetic influences, and low educational attainment contributed to risk for total dementia. These findings identify possible risk factors but do not show that any intervention prevents or treats dementia.
New to this subject? Start with our plain-English guide: Prevention →
Study details
- Study designcase-control study
- Participants310
- Evidence strengthModerate
How this study scored 62/100
Published in a leading specialty journal, and it is a case-control study. Scored zero for effect reported and randomised / blinded because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 9 / 10 | Tier 2 — leading specialty journal (Alzheimer's & dementia : the journal of the Alzheimer's Association) |
| Journal's citation record | 2 / 4 | Alzheimer s & Dementia: journal h-index 228 (OpenAlex, 2026-10-29) |
| Study design | 6 / 12 | A case-control study |
| 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 | 1 / 5 | 2006 — older than 20 years, still counted |
| Sample size | 2 / 4 | 310 participants |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| 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 | 5 / 7 | Cited 238 times (OpenAlex, 2026-10-10) |
| Citations per year | 3 / 5 | 10.8 citations a year over 22 year(s) since 2006 |
| Impact for its field and year | 3 / 6 | Cited 5.7× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 3 / 6 | Cited by 12 other studies in this library |
| Still being cited | 2 / 4 | Cited 22 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 4 / 4 | Last-listed author Nancy L. Pedersen: h-index 167 (OpenAlex, whole career) |
| Institution's track record | 2 / 3 | University of Southern California: institution h-index 1,521 (OpenAlex) |
| Multi-centre collaboration | 2 / 3 | OpenAlex lists 6 institution(s) in 2 countries |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 19595867) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Total | 62 / 100 | — |
What each of these 20 components measures, and what this score is not →
Read the original
May need a subscription OpenAlex found no free copy of the full text (checked 6 Feb 1020), so the publisher may charge for it. The PubMed abstract is free.
Studies this one cites
Referenced by this study and also in the alzhub library, so you can read them here.
Later studies that cite this one
12 studies in the alzhub library list this one in their references. Showing the 8 highest-scoring.
Related studies in Prevention and risk
Also tagged “incidence”
1,084 studies in the library carry the topic tag “incidence”; 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.