All subjects were directly interviewed using a battery of structured interviews assessing tics, obsessive-compulsive symptoms, and ADHD symptoms using a clinician-reviewed self-report instrument developed by the TSAICG43. Present and worst-ever lifetime tic severity was assessed using the Yale Global Tic Severity Scale (YGTSS)45. Additional diagnostic instruments included the Yale Brown Obsessive Compulsive Inventory (YBOCS), adult or child version, as appropriate, the Diagnostic Confidence Index (DCI) to assess the confidence of the tic diagnoses, the Kiddie- Schedule for Affective Disorders and Schizophrenia (K-SADS) for children and the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID) for adults46, 47. Diagnoses of TS, CMVT, OCD, and ADHD were made by two or more independent clinicians using a best-estimate/consensus approach and following DSM-IV criteria13, 48. A diagnosis of OCB was made when symptoms were present but time and severity criteria were not met (i.e., the subject had at least mild distress and interference, but the symptoms took up less than one hour a day).
