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71/100

✓ Peer-reviewed alzhub usefulness score 71 out of 100. Risk factors

Topic: Risk, prevention and care in population studies

Plain-language summary

Objective The relation of overweight to dementia is controversial. We aimed to examine the association of midlife overweight and obesity with dementia, Alzheimer disease (AD), and vascular dementia (VaD) in late life, and to verify the hypothesis that genetic and early-life environmental factors contribute to the observed association. Methods From the Swedish Twin Registry, 8,534 twin individuals aged ≥65 (mean age 74.4) were assessed to detect dementia cases (DSM-IV criteria). Height and weight at midlife (mean age 43.4) were available in the Registry. Data were analyzed as follows: 1) unmatched case-control analysis for all twins using generalized estimating equation (GEE) models and 2) cotwin matched case-control approach for dementia-discordant twin pairs by conditional logistic regression taking into account lifespan vascular disorders and diabetes. Results Among all participants, dementia was diagnosed in 350 subjects, and 114 persons had questionable dementia. Overweight (body mass index [BMI] >25-30) and obesity (BMI >30) at midlife were present in 2,541 (29.8%) individuals. In fully adjusted GEE models, compared with normal BMI (20-25), overweight and obesity at midlife were related to dementia with odds ratios (ORs) (95% CIs) of 1.71 (1.30-2.25) and 3.88 (2.12-7.11), respectively. Conditional logistic regression analysis in 137 dementia-discordant twin pairs led to an attenuated midlife BMI-dementia association. The difference in ORs from the GEE and the matched case-control analysis was statistically significant (p = 0.019). Conclusions Both overweight and obesity at midlife independently increase the risk of dementia, AD, and VaD. Genetic and early-life environmental factors may contribute to the midlife high adiposity-dementia association.

What this study adds

Evidence grade: Moderate

This is a case-control study of 350 participants. Among 8,534 Swedish twins, people who were overweight or obese around age 43 had higher odds of dementia after 65 (odds ratios 1.71 and 3.88 versus BMI 20–25). Reported effect size: 29.8%.

Taken from this record’s own fields, not from reading the paper. The grade is assigned from the abstract’s wording; what that means.

Cite this study APA, Vancouver, BibTeX · download .bib or .ris

APA 7th

Xu, W. L., Atti, A. R., Gatz, M., Pedersen, N. L., Johansson, B., & Fratiglioni, L. (2011). Midlife overweight and obesity increase late-life dementia risk: a population-based twin study. Neurology. https://doi.org/10.1212/wnl.0b013e3182190d09

Vancouver

Xu WL, Atti AR, Gatz M, Pedersen NL, Johansson B, Fratiglioni L. Midlife overweight and obesity increase late-life dementia risk: a population-based twin study. Neurology. 2011. doi:10.1212/wnl.0b013e3182190d09. PMID: 21536637.

BibTeX

@article{xu2011-21536637,
  author  = {Xu, W. L. and Atti, A. R. and Gatz, M. and Pedersen, N. L. and Johansson, B. and Fratiglioni, L.},
  title   = {{Midlife overweight and obesity increase late-life dementia risk: a population-based twin study}},
  journal = {Neurology},
  year    = {2011},
  doi     = {10.1212/wnl.0b013e3182190d09},
  pmid    = {21536637},
  url     = {https://doi.org/10.1212/wnl.0b013e3182190d09}
}

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How to read this study

Design: this is a case-control study. People with the condition are compared with people without it, looking backward at past exposures. Recall of the past can be uneven between the groups, and the design shows association, not cause.
Size: the record lists 350 participants. Ask whether that is enough for the question, and who they were.
Effect: the record reports “29.8%”. A statistically significant result can still be small in daily life.

What the evidence grade means here

This page is graded moderate. alzhub.org assigns the grade automatically from keywords in the abstract, not from reading the paper. Moderate means the abstract mentions a cohort, case-control or longitudinal design. It can add at most 5 of the 100 points in the study score, and it is a label about design, not a verdict on whether the findings are true.

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Key findings

Results Among all participants, dementia was diagnosed in 350 subjects, and 114 persons had questionable dementia.
In fully adjusted GEE models, compared with normal BMI (20-25), overweight and obesity at midlife were related to dementia with odds ratios (ORs) (95% CIs) of 1.71 (1.30-2.25) and 3.88 (2.12-7.11), respectively.
The difference in ORs from the GEE and the matched case-control analysis was statistically significant (p = 0.019).

Why it matters

Among 8,534 Swedish twins, people who were overweight or obese around age 43 had higher odds of dementia after 65 (odds ratios 1.71 and 3.88 versus BMI 20–25). When twins were compared with their own co-twin in 137 pairs, the link was weaker, which the authors say suggests genes and early-life environment explain part of it. This is an association from observational data; the study did not test whether changing weight changes dementia risk.

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Study details

Study designcase-control study
Participants350
Effect size29.8%
Evidence strengthModerate

How this study scored 71/100

Published in a leading specialty journal, and it is a case-control study. Scored zero for randomized / blinded 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	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	2011 — within 20 year(s) of the newest study here
Sample size	2 / 4	350 participants
Effect reported	2 / 3	Effect reported as a number, without an interval or test
Studied in people	3 / 3	Studied in people (participant count stated)
Randomized / blinded	0 / 2	No randomization or blinding stated — scores zero (not stated in the record — scored 0)
Times cited	6 / 7	Cited 479 times (OpenAlex, 2026-10-10)
Citations per year	4 / 5	28.2 citations a year over 17 year(s) since 2011
Impact for its field and year	5 / 6	Cited 21.0× the average for papers of its field and year (OpenAlex FWCI)
Cited by studies here	3 / 6	Cited by 22 other studies in this library
Still being cited	3 / 4	Cited 82 times in 2024–2026 (2026 still in progress; OpenAlex)
Senior author's track record	4 / 4	Last-listed author Laura Fratiglioni: h-index 133 (OpenAlex, whole career)
Institution's track record	2 / 3	University of Southern California: institution h-index 1,521 (OpenAlex)
Multicenter collaboration	2 / 3	OpenAlex lists 5 institution(s) in 4 countries
Indexed in PubMed	2 / 2	Indexed in PubMed (PMID 21536637)
Free to read	0 / 2	Behind a paywall — scores zero
Total	71 / 100	—

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