Integrating Exposure and Response Prevention and Habit Reversal Techniques to Treat a Tourettic Subtype of Obsessive-Compulsive Disorder (Tourettic OCD)

Participants are randomly allocated to one of four groups: (1) combined ERP and HbRT, (2) ERP alone, (3) HbRT alone, or (4) a supportive psychoeducation control. All participants receive 12 weekly one-to-one sessions (either in-person or remotely) of approximately fifty minutes. Symptoms will be assessed using the Yale Global Tic Severity Scale (YGTSS) and Yale-Brown Obsessive Compulsive Scale (Y-BOCS) by an independent clinician at the start of treatment, at Week 12, and again at Week 24.

• Exposure and Response Prevention (ERP) (Behavioral): Exposure and Response Prevention (ERP) is a behavioural intervention that involves gradual and systematic exposure to obsessional fears, distress, sensory discomfort, premonitory urges, and "not-just-right" experiences while refraining from compulsions, avoidance, reassurance seeking, and other safety behaviours. Treatment is delivered individually over 12 weekly 50-minute sessions, either face-to-face or remotely.
• Habit Reversal Training (HbRT (Behavioral): Habit Reversal Training (HbRT) is a behavioural intervention that includes awareness training, identification of premonitory urges and antecedents to tic expression, development and practice of competing responses, and strategies to generalise skills across settings. Treatment is delivered individually over 12 weekly 50-minute sessions, either face-to-face or remotely.
• Psychoeducation and Supportive Intervention (Behavioral): Psychoeducation and Supportive Therapy consists of structured education about obsessive-compulsive disorder, tic disorders, Tourettic obsessive-compulsive disorder, stress, and wellbeing, together with supportive discussion and general problem-solving. The intervention does not include Exposure and Response Prevention, Habit Reversal Training, or other targeted behavioural techniques. Treatment is delivered individually over 12 weekly 50-minute sessions, either face-to-face or remotely.

Primary outcomes

• Change From Baseline in Yale-Brown Obsessive Compulsive Scale Total Score [Baseline, Week 12 and Week 24]: Obsessive-compulsive symptom severity will be assessed using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). Total scores range from 0 to 40, with higher scores indicating greater obsessive-compulsive symptom severity. Change from baseline will be assessed at Week 12 and Week 24.
• Change From Baseline in Yale Global Tic Severity Scale Total Tic Severity Score [Baseline, Week 12 and Week 24]: Tic symptom severity will be assessed using the Yale Global Tic Severity Scale (YGTSS) Total Tic Severity Score. Scores range from 0 to 50, with higher scores indicating greater tic symptom severity. Change from baseline will be assessed at Week 12 and Week 24.

Secondary outcomes

• Change From Baseline in Yale Global Tic Severity Scale Global Severity Score [Baseline, Week 12 and Week 24]: Overall tic symptom severity and tic-related impairment will be assessed using the Yale Global Tic Severity Scale (YGTSS) Total Score. The Global Score is calculated by summing the Total Tic Severity Score (0-50) and the Impairment Score (0-50), resulting in a global score ranging from 0 to 100. Higher scores indicate greater overall tic severity and impairment. Change from baseline will be assessed at Week 12 and Week 24.

Sex: All, ages: 18 Years to 65 Years

Inclusion Criteria:

1. Age 18 years or older
2. All genders
3. Confirmation of a primary diagnosis of either:

a. Tourettes Disorder / Tourette Syndrome b. Persistent Motor or Vocal Tic Disorder / Chronic Motor or Vocal Tic Disorder c. Provisional Tic Disorder / Transient Motor Tics d. Other Specified Tic Disorder e. Unspecified Tic Disorder f. Obsessive-Compulsive Disorder \[d\] Participants taking psychotropic medication are eligible provided medication type and dose remain stable throughout the intervention period \[e\] Ability to provide sustained informed consent \[f\] A minimum score of 16 on YBOCS \[g\] A minimum score of 5 on the Premonitory Urge for Tics Scale (PUTS)

Exclusion Criteria:

1. Substance misuse
2. Current diagnosis of a personality disorder
3. Schizophrenia
4. Bipolar disorder
5. Contraindications to participation in a trial (i.e., active suicidal ideations and/or requirement of an interpreter)
6. Any psychiatric or neurological condition that, in the opinion of the investigators, would interfere with participation or interpretation of study outcomes.