Brown adipose and central nervous system glucose uptake is lower during cold exposure in older compared to young men: a preliminary PET study.

The purpose of this study was to determine the activity of brown adipose tissue (BAT) and the central nervous system (CNS) during cold exposure in young and older men. Two young, 24 and 21 years, and two older, 76 and 74 years, men participated in the study. Positron emission tomography images showed cold-induced BAT activity was absent in older men but clearly present in the clavicular region of the young men (Standardized Uptake Value: SUVmean: 3.12 and 3.71). Statistical parametric mapping revealed cortical brain activity was lower in the older men within areas of the frontal, parietal, temporal, and occipital lobes, and the thalamus (peak-level p uncorr  < 0.036). Cervical spinal cord SUVmean values tended to be lower for older (SUVmean: 1.64 and 1.61) compared to young men (SUVmean: 1.91 and 1.71). These preliminary findings suggest lower BAT activity in older men may in part be due to lower CNS activity.