Panel A: Significant reductions (p < 0.05) were seen in serotonin transporter (SERT) BP in the midbrain, caudate, and putamen of subjects with Tourette syndrome (TS), when compared with normal controls. Panel C: No significant differences were seen in serotonin receptor (5-HT2AR) BP between TS and normal controls (p > 0.05). Panel B: When grouped by OCD status, the TS+OCD groups displayed significant decreases in SERT BP in midbrain, as compared with normal controls (p < 0.05). Panel D: When grouped by OCD status, TS+OCD subjects showed slightly higher 5-HT2A binding, but these results were not significant (p>0.1).