Overview

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.

Eligibility

Inclusion Criteria:

≥ 18 years of age.

Primary diagnosis of TS/CTD, according to criteria in Diagnostic and Statistical Manual of mental disorders 5th edition.

Provided digital informed consent.

Have a Total Tic Severity Score (TTS) of >15, or >10 for individuals with motor or vocal tics only, in the past week, as measured by the Yale Global Tic Severity Scale (YGTSS).

Being willing and able to follow the study procedures and participate in the 10-week treatment program.

Being fluent in Swedish.

Have regular access to a computer connected to the Internet, sufficient technical skills to use the treatment platform, as well as a mobile phone to receive text messages.

Exclusion Criteria:

Ongoing or planned psychological treatment for TS/CTD.

Previous BT for tics of a minimum of 8 sessions with a qualified therapist within 12 months prior to assessment.

Adjustment of medication for tics within the last two months prior to assessment.

Severe psychiatric comorbidities such as organic brain disorders, bipolar disorder, ongoing psychosis, anorexia nervosa or substance use disorders that can interfere with the treatment for TS/CTD.

Acute psychiatric problems such as severe depression or suicidal risk needing immediate psychiatric care.

Severe tics causing immediate risk to the participants themselves or to others and requiring urgent medical attention.