Evaluation of Inference-Based Therapy (Doubt Therapy) as a Self-Help Tool for Obsessive-Compulsive Disorder

Introduction: Inference-based therapy (IBT) is a novel therapeutic approach aimed at reducing obsessive-compulsive symptoms. For this study, the original therapist-guided protocol was adapted for self-help administration. Method: Fifty patients with obsessive-compulsive disorder who had been recruited via specialized online fora were randomly allocated to either IBT or a wait-list control condition. At baseline and 4 weeks later, questionnaires tapping into psychopathology, quality of life, and faulty reasoning were administered. Results: The completion rate was acceptable (74%) and not significantly different across groups. Relative to controls, patients in the IBT group showed modest but significant symptom decline on obsessions (Yale-Brown Obsessive-Compulsive Scale [Y-BOCS] self-report and Obsessive–Compulsive Inventory—Revised [OCI-R]) and washing compulsions (OCI-R) across time. No significant differences emerged for depression, quality of life, and inferential confusion. Ratings at the post-assessment suggest that the training was well accepted among patients. Test–retest reliability was high indicating good quality of the data. Discussion: This study confirms prior research suggesting that IBT is effective as a stand-alone technique. Follow-up studies are needed to elucidate the long-term effects of the training and whether positive effects are maintained if IBT is introduced as an add-on to standard treatment (i.e., cognitive behavioral therapy/medication).