Internet-based Behavior Therapy for Adults With Tourette Syndrome

This study protocol outlines a parallel-group, randomized controlled trial (RCT) designed to evaluate the effectiveness of Internet-delivered behavior therapy (BT) based on exposure with response prevention (ERP) for adults with Tourette syndrome (TS) or chronic tic disorder (CTD). The primary aim is to evaluate the effects of Internet-delivered ERP-based BT on tic severity compared to a control condition offering general psychological support at week 11 counting from the treatment start. The primary outcome measure is the Yale Global Tic Severity Scale - Total Tic Severity subscale (YGTSS-TTS). Secondary outcomes include measures of tics-related impairment, work and social adjustment, rates of responders, self-rated tic severity, symptoms of depression, and quality of life. Long-term maintenance of results will be assessed at week 23 and 14 months after the treatment start. Participants will be recruited nationwide. The intervention group will receive 10 weeks of ERP-based therapy delivered through an online platform, with therapist support. The control group will receive psychoeducational content and general psychological support. Adherence to treatment, adverse events, and patient safety will be closely monitored throughout the trial. The study population will be intent-to-treat and the between-group differences at the primary endpoint will be assessed using an analysis of covariance (ANCOVA) with pre-score of the measure as covariate. A health-economic evaluation will assess the cost-effectiveness of the intervention.