Fat distribution differs in symptom-free dementia mutation carriers
Body scans compared 13 symptom-free mutation carriers with 27 non-carriers and found differences in fat distribution and fat around internal organs.
Our read
Biomarkers- Studied:
- Cross-sectional study of symptom-free people, against non-carriers
- What changed:
- Symptom-free mutation carriers had a lower ratio of trunk fat to hip-and-thigh fat than non-carriers
- The catch:
- Only 13 carriers and 27 non-carriers had body scans
Editor of record: Boris Djordjevic · AgingResearch.News
Researchers conducted a cross-sectional observational study of 44 symptom-free people: 16 carried an expansion in the dementia-linked gene C9orf72, and 28 did not. All had brain scans; 13 carriers and 27 non-carriers also had a single whole-body scan measuring fat and lean mass.
Carriers had a lower ratio of trunk fat to hip-and-thigh fat and a smaller area of fat around internal organs than non-carriers. Carriers were on average 11–12 years before expected symptom onset. Total fat and lean mass did not differ between groups. In the pooled analysis of carriers and non-carriers, lower trunk-to-hip-and-thigh fat ratios and lower lean mass were associated with smaller volumes in several brain regions.
Why it matters
The authors interpret the findings as evidence that early changes in genetic frontotemporal dementia and amyotrophic lateral sclerosis extend beyond thinking and movement symptoms to broader body functions.
Caveats
Single body scans cannot establish changes over time or whether brain differences caused body composition differences. This small study excluded people with neurological, cognitive or psychiatric abnormalities, so its findings do not describe symptomatic patients.
- C9ORF72EXPANSION
- Lean mass
- Frontotemporal dementia
- Android-to-gynoid ratio
- Cortical, subcortical and thalamic volumes
- Humans
The paper
Changes in body composition in genetic C9orf72 carriers: The role of the hypothalamus and thalamus
The University of Sydney
Alzheimer's & Dementia, Jul 2026, Open access
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