Changes in abdominal subcutaneous adipose tissue thickness associate with disease and anthropometric factors

Background: Three-dimensional (3D) mesh-derived phenotypes enable detailed characterisation of organ morphology and regional variation through statistical parametric maps (SPMs) and statistical shape analysis (SSA). While these techniques have been widely used for organ studies, their application to abdominal subcutaneous adipose tissue (ASAT) has been limited. This study investigates the associations between ASAT thickness, anthropometric traits, and clinical conditions, including type 2 diabetes (T2D) and hypertension. Methods: We analysed ASAT using MRI data from 44,515 participants in the UK Biobank who underwent baseline imaging, with a subset of 3088 participants receiving a follow-up scan approximately 2 years later. ASAT thickness was quantified using 3D surface meshes. Regional associations with anthropometric and clinical variables were examined using SPMs. Additionally, principal components of ASAT thickness, derived via SSA, were analysed for their association with future cardiovascular disease (CVD) risk. Results: ASAT thickness was significantly associated with age, alcohol consumption, visceral fat, total muscle mass, and various health-related traits. Longitudinal analysis revealed significant changes in ASAT thickness over a 2.5-year period in both sexes, independent of disease status at baseline. Notably, regional variations in hip ASAT thickness were associated with incident CVD in women (hazard ratio [HR]: 0.90, 95% CI: 0.84–0.97, p = 0.023) and with hypertension in both women (HR: 1.10, 95% CI: 1.03–1.21, p = 0.045) and men (HR: 0.88, 95% CI: 0.82–0.96, p = 0.014). Conclusions: 3D quantification and morphometric analysis of ASAT offer novel insights into the associations between abdominal fat distribution, lifestyle factors, and chronic disease risk. These techniques hold promise for enhancing our understanding of fat-related disease mechanisms in population-level studies.