Efficacy and mediators of online cognitive therapy for taboo obsessions in adults with obsessive-compulsive disorder: Randomized controlled trial.

Taboo obsessions are ego-dystonic, recurrent, and intrusive thoughts involving aggressive, sexual and/or religious themes, which are common in individuals with obsessive-compulsive disorder (OCD). These symptoms are often challenging to treat with traditional, exposure-based approaches. Our research group has developed and successfully piloted an Internet-delivered intervention based on the cognitive framework of taboo obsessions (I-CT). The current randomized controlled trial evaluated the efficacy of I-CT compared to Internet-delivered general psychological support in reducing OCD symptom severity and associated impairments. A secondary aim was to investigate if the treatment effect was mediated by a reduction in negative appraisals, the proposed mechanism of change in cognitive therapy. Sixty-eight participants with a diagnosis of OCD and primary taboo obsessions were randomized to either I-CT or general psychological support for 8 weeks. The primary outcome was change on the clinician-rated Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), administered by masked assessors at pre- and post-treatment. Participants in both groups had a significant reduction of OCD symptom severity but those randomized to I-CT had significantly better outcomes (between group bootstrapped d = 0.69, [95% CI, 0.22-1.17]). The proportion of participants classed as responders and remitters was also higher in the I-CT group (odds ratio 2.33 and 1.77 respectively), though not significantly. A large portion of the treatment effect (55%) was mediated by change in negative appraisals. I-CT could be a promising treatment approach for individuals with taboo obsessions who do not wish, or are unable, to engage in, or do not respond to, exposure-based treatment for OCD.