Objectives The aim of this study was to evaluate whether computed tomography (CT) attenuation, as a measure of fat quality, is associated with cardiometabolic risk factors above and beyond fat ...quantity. Background Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) are pathogenic fat depots associated with cardiometabolic risk. Adipose tissue attenuation in CT images is variable, similar to adipose tissue volume. However, whether the quality of abdominal fat attenuation is associated with cardiometabolic risk independent of the quantity is uncertain. Methods Participants were drawn from the Framingham Heart Study CT substudy. The VAT and SAT volumes were acquired by semiquantitative assessment. Fat quality was measured by CT attenuation and recorded as mean Hounsfield unit (HU) within each fat depot. Sex-specific linear and logistic multivariable regression models were used to assess the association between standard deviation (SD) decrease in HU and each risk factor. Results Lower CT attenuation of VAT and SAT was correlated with higher body mass index levels in both sexes. Risk factors were generally more adverse with decreasing HU values. For example, in women, per 1 SD decrease in VAT HU, the odds ratio (OR) was increased for hypertension (OR: 1.80), impaired fasting glucose (OR: 2.10), metabolic syndrome (OR: 3.65), and insulin resistance (OR: 3.36; all p < 0.0001). In models that further adjusted for VAT volume, impaired fasting glucose, metabolic syndrome, and insulin resistance remained significant. Trends were similar but less pronounced for SAT and for men. There was evidence of an interaction between HU and fat volume among both women and men. Conclusions Lower CT attenuation of VAT and SAT is associated with adverse cardiometabolic risk above and beyond total adipose tissue volume. Qualitative indices of abdominal fat depots may provide insight regarding cardiometabolic risk independent of fat quantity.
Background Perivascular fat may have direct effects on local vascularity. Neck fat is associated with carotid intimal thickness, a predictor of brain aging outcomes. This study investigated whether ...neck circumference, an estimation of neck fat, has unique associations with brain aging outcomes. Methods The study sample (n = 2082, 53.5% women, mean age 60.9 years) was derived from Framingham Heart Study participants with brain magnetic resonance imaging (MRI) and neuropsychological (NP) test measures. Multivariable-adjusted regressions examined cross-sectional associations of neck circumference with brain MRI and NP test measures. Models were also constructed with waist circumference and body mass index (BMI) as exposures. Results A 1 standard deviation (2.8 cm women; 2.9 cm men) increment in neck circumference was associated with lower total cerebral brain volume (β = −.22, P = .0006) and lower frontal brain volume (β = −.55, P < .0001). However, a similar association was observed for both waist circumference and BMI. There were no associations between neck circumference and NP test measures after full covariate adjustment. Conclusions There were no unique associations between neck circumference and brain MRI or NP measures. Consistent with prior observations, all adiposity measures showed associations with more adverse brain MRI and NP measures, suggesting a global association of generalized adiposity.
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