Is Acceptance and Commitment Therapy Effective for Any Obsessive-Compulsive Symptom Dimensions?

OBJECTIVE: Acceptance and commitment therapy (ACT) has been recently introduced for treating obsessive-compulsive disorder (OCD). Although there are data supporting the efficacy of ACT, only few studies have investigated the effectiveness of ACT against any obsessivecompulsive (OC) symptom dimension or a specific dimension alone. METHODS: In total, 64 patients with OCD received an 8-session ACT group program. All measures were evaluated before and after treatment. The Dimensional Obsessive-Compulsive Scale was used to assess OCD severity across the four empirically supported symptom dimensions (i.e., contamination, responsibility for harm, unacceptable thoughts, and symmetry). ACT processes were evaluated using the Acceptance and Action Questionnaire-II (AAQ-II), Acceptance and Action Questionnaire for Obsessions and Compulsions (AAQOC), and Cognitive Fusion Questionnaire. RESULTS: After an 8-week program, there were significant reductions in all four OC symptom dimensions after ACT. The unacceptable thoughts and contamination domains had medium effect size. The responsibility for harm and symmetry dimensions had small effect size. The unacceptable thoughts dimension was significantly correlated with all ACT process measures. The symmetry dimension was significantly correlated with AAQ-OC and AAQ-II scores while the responsibility for harm dimension was correlated with AAQ-II alone. However, the contamination dimension was not associated with any process measures. CONCLUSION: ACT may be effective for managing all four symptom dimensions with small to moderate effect size. Moreover, depending on the symptom dimension, there may be different relationship patterns between symptom reduction and changes in ACT processes.