Chronic tics are a disabling neuropsychiatric symptom associated with multiple child-onset mental disorders. Chronic tics affect 1-3% of youth 1 and are associated with impaired functioning, emotional and behavioral problems, physical pain, diminished quality of life, peer victimization, and a fourfold increased risk of suicide compared to the general population. Large randomized trials have demonstrated the superiority of CBIT over supportive therapy in child and adult patients. However, in these trials, only 52% of children and 38% of adults showed clinically meaningful tic improvement, meaning that 50-60% of patients do not benefit from CBIT. CBIT success relies on an ability to suppress tics that many youth lack. The central aim of CBIT is to enhance voluntary tic suppression. Better tic suppression ability drives CBIT improvement 10 and predicts lower tic burden over the course of illness. During the core CBIT procedure, competing response training, patients learn to inhibit tics by engaging in a competing motor action. However, research shows that many youth lack this fundamental tic suppression ability that CBIT aspires to enhance.

This study will examine the clinical and neural effects of a treatment combining Comprehensive Behavioral Intervention for Tics (CBIT) and transcranial magnetic stimulation (TMS) to the supplementary motor area (SMA) in young people with tic disorder.

Inclusion Criteria:

• Age 12-21 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, consenting parent, and adult participant required to have English fluency and literacy 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 6 weeks and expect to remain stable for the approximately 3-week intervention protocol (with the exception of those taking neuroleptic/antipsychotic medications). Those who previously received tic-specific therapy will be included if they meet the tic severity criterion.

Youth receiving other forms of psychotherapy will be included provided these treatments are not focused on tics. All concurrent treatments will be monitored during the study period.

Exclusion Criteria:

• Medical conditions contraindicated or associated with altered TMS risk profile, including history of intracranial pathology, epilepsy or seizure disorders, traumatic brain injury, brain tumor, stroke, implanted medical devices or metallic objects in the head, current pregnancy or girls of childbearing age not using effective contraception, or any other medical condition deemed serious or contraindicated by a study physician.
• Inability to undergo MRI (e.g., metal in body, claustrophobia, orthodontia)
• Active suicidality.
• Previous diagnosis of psychosis or cognitive disability.
• Substance abuse or dependence within the past year.
• Concurrent psychotherapy focused on tics.
• Neuroleptic/antipsychotic medications.
• Pregnant according to the medical history or a urine pregnancy test; and menstruating individuals capable of becoming pregnant and not using a highly effective form of contraception (FDA-approved hormonal contraceptive, IUD, tubal ligation)
• Taking a medication that has not reached stability criterion (same medication and dose for 6 weeks with no planned changes over the intervention period)