SLC6A4 and Compulsive behaviors: Here, we investigated for the first time SERT binding in TS patients with and without OCD (TS − OCD) compared to both healthy controls (HC) and OCD patients as well as the influence of escitalopram using the potent SERT imaging ligand [123I]2-((2-((dimethylamino)methyl)phenyl)thio)-5-iodophenylamine ([123I]ADAM) and single-photon emission tomography (SPECT).