Brain scans may reveal why behavioral therapy helps some teens with tics

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Age 10-17 years at time of enrollment. * Current chronic motor and/or vocal tics, defined as tics for at least 1 year without a tic-free period of more than 3 consecutive months. Tics must not be due to a medical condition or the direct physiological effects of a substance. * At least moderate tic severity, defined as a Yale Global Tic Severity Scale total score ≥14 (≥9 for those with motor or vocal tics only). * Full scale IQ greater than 70. * Child participant required to have English fluency to ensure comprehension of study measures and instructions. * To increase external validity of findings, we will include participants taking psychotropic medications that have been stable for 4 weeks and expect to remain stable for the study period. Individuals receiving non-tic related psychotherapy involving procedures that overlap with CBIT can be eligible to participate if they refrain from receiving treatment once enrolled through the post-treatment assessment. All concurrent treatments will be monitored. Exclusion Criteria: * Inability to undergo MRI (e.g., metal in body, claustrophobia, orthodontia) and/or EEG. * Active suicidality Previous diagnosis of psychosis, cognitive disability, or structural brain disease that in the investigator opinion would impede participation. * History of seizure disorder * Active substance abuse or dependence. * Presence of another psychiatric or medical condition requiring immediate treatment and/or for which delay of treatment to focus on tics would be clinically inappropriate. Participants will not be excluded for comorbidities that commonly occur with TS (e.g., ADHD, OCD, anxiety) provided that this criterion is met, as only 10-15% of patients with TS have no comorbidities. * Concurrent psychotherapy focused on tics and/or involving procedures that overlap with CBIT (e.g., habit reversal therapy, exposure therapy targeting repetitive behaviors). * Psychotropic medication changes in the past 4 weeks and/or plans to change medication during the study period through post-treatment assessment. * ≥ 4 previous sessions of CBIT.