The metabolic anatomy of Tourette's syndrome

The functional brain networks underlying the clinical manifestations of Gilles de la Tourette's syndrome (TS) are currently unknown. To identify these networks, we studied TS patients and normal subjects with 18F- fluorodeoxyglucose (FDG) and PET employing a statistical model of regional metabolic covariation. We studied 10 TS patients (mean age, 41.5 ± 12.7 years) who were either drug naive or medication free for at least 2 years. Ten normal volunteers (mean age, 42.5 ± 11.5) served as controls. We used quantitative FDG/PET to calculate global, regional, and normalized rates of glucose metabolism (GMR, rCMRGlc, and rCMRGlc/GMR) in all subjects. The Scaled Subprofile Model (SSM) was used to identify specific patterns of regional metabolic covariation associated with TS. We found that global and regional metabolic rates were normal in TS. SSM analysis identified two TS- related brain networks. One pattern (15.8% variance accounted for, VAF) was characterized by covariate bilateral metab...