Internet-based acceptance and commitment therapy for obsessive-compulsive symptoms: A randomized controlled trial.

Subthreshold obsessive-compulsive symptoms (OCS) are associated with increased distress, help seeking behaviours, and functional problems, and may predict progression into further mental health problems. This study investigated the effectiveness of a four-module internet-based acceptance and commitment therapy (iACT) for adults with OCS compared to internet-based progressive relaxation training (iPRT). Eighty-nine adults with OCS participated in a single-blinded randomised controlled trial of iACT or iPRT. Self-report assessments of OCS, psychological flexibility, and quality of life, among others, were measured at baseline, post-treatment, and at three-month follow-up. Both iACT and iPRT showed large pre-post improvements in OCS (b = 6.32, p < 0.001, d = 0.8) and medium improvements in psychological flexibility (b = -0.38, p = 0.011, d = 0.47) and quality of life (b = -5.26, p = 0.008, d = 0.58), with no significant differences in effects between groups. All improvements were maintained at follow-up. There were no differences in attrition or adherence between groups. iACT was rated more favourably by participants at post-treatment, and there were some differences in qualitative feedback across groups. These findings suggest both iPRT and iACT may be helpful in improving mental health in adults with OCS, but that iACT may be more acceptable.