Cognitive mechanisms of change in OCD: Inferential confusion, obsessive beliefs, and mindfulness across three randomized treatments

Cognitive-behavioral therapy (CBT) with exposure and response prevention (ERP) is widely regarded as the gold-standard psychological treatment for obsessive–compulsive disorder (OCD). Inference-based cognitive behavioral therapy (I-CBT) represents a distinct cognitive approach that targets inferential confusion, defined as a reasoning process whereby imagined possibilities are treated as reflecting reality, without relying on deliberate exposure. The present study reports further mechanism-focused analyses from a previously published multicenter randomized controlled trial (Aardema et al., 2022; ClinicalTrials.gov Identifier: NCT01794156) comparing CBT with ERP, I-CBT, and mindfulness-based stress reduction (MBSR) for OCD. A total of 111 participants with a primary diagnosis of OCD were randomized to one of three treatment conditions. Across treatments, therapy was associated with significant reductions in inferential confusion and obsessive belief domains, whereas dispositional mindfulness did not show significant change. At the bivariate level, residualized changes in inferential confusion, obsessive belief domains, and mindfulness were associated with reductions in OCD symptoms. However, when examined concurrently using mixed-effects models, only reductions in inferential confusion accounted for unique symptom improvement over time. This association was consistent across modalities and remained robust after controlling for concurrent anxiety and depression. Sensitivity analyses indicated that psychotropic medication use did not account for this association; controlling for medication strengthened the independent contribution of inferential confusion (partial η 2 ≈ .29). These findings indicate that inferential confusion was independently associated with symptom improvement in OCD across therapeutic approaches.