Need for speed: Evaluating slopes of OCD recovery in behavior therapy enhanced with d-cycloserine

Evidence suggests that the antibiotic d-cycloserine (DCS) enhances the treatment effects of exposure and response prevention (ERP) for Obsessive–Compulsive Disorder (OCD). Further, evidence suggests that the effects of DCS diminish partway through treatment, but it is unclear to what extent. In an effort to evaluate these issues, the current study re-analyzes data from a 10-session randomized controlled trial of ERP + DCS versus ERP + placebo in a sample of 22 adults with OCD. We analyzed repeated-measures mixed models with random slopes and intercepts across different intervals: sessions 1–10, 1–5, and 6–10. The results indicate that the course of ERP was 2.3 times faster over the full 10 sessions for the DCS compared to the placebo group, and nearly six times quicker in the first half of ERP. Further interpretation of the results suggests that DCS does not amplify the effects of ERP, but instead initiates treatment effects sooner in treatment. In addition, DCS does not necessarily lose its effect over repeated use, but instead may exhaust its maximum utility after effectively jump-starting ERP. Ultimately, DCS may provide a means for curtailing treatment costs, decreasing treatment dropout and refusal rates, and enhancing access to care.