Challenging heights: Findings from a proof-of-principle randomized controlled trial testing interpretation bias modification as an adjunct to exposure therapy for acrophobic patients

Exposure is highly effective for treating acrophobia and there is growing consensus that cognitive mechanisms play an important role in exposure-based therapies. The present randomized controlled trial investigated whether adding a Cognitive Bias Modification - Interpretation (CBM-I) training to a single-session exposure therapy further facilitates cognitive change. The sample included diagnosed acrophobia patients (N = 81), all of whom received exposure therapy. One day later they were randomized to receive either CBM-I or a sham training. The CBM-I trained patients to interpret and appraise ambiguous, height-related scenarios in a less threatening and adaptive manner, whereas the sham training comprised ambiguous, neutral scenarios. Outcomes included changes in interpretational biases (Encoding Recognition Task, Heights Interpretation Questionnaire, Scrambled Sentences Task), acrophobia-related symptoms (Acrophobia Questionnaire), and behavioral avoidance (Behavioral Approach Test). In intention-to-treat analyses patients receiving CBM-I showed a greater reduction in interpretational biases post-training compared to the sham condition (primary outcome). However, group differences were not sustained at follow-up, with both groups demonstrating improvements across all outcomes, except for the Scrambled Sentences Task. No significant group differences in reductions in other acrophobia-related cognitions, symptoms, or behavior emerged over time. Exploratory analyses revealed strong associations between the assessed cognitive, behavioral, and subjective outcomes, but not with the hormonal measures (progesterone, estradiol). To conclude, our findings suggest that while CBM-I can temporarily facilitate cognitive change in the context of exposure, its long-term benefits and downstream effects may require further optimization. Future research should refine CBM-I protocols to maximize its efficacy as a potential adjunct to exposure therapy.