Neck Circumference, Brain Imaging Measures, and Neuropsychological Testing Measures

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.