Exploring the Peaks and Potholes: Understanding positive and negative effects of concentrated exposure treatment for obsessive-compulsive disorder

The Bergen 4-Day Treatment offers brief concentrated exposure with response prevention (cERP) for obsessive-compulsive disorder (OCD). To date, this intervention has primarily been studied in Norway, and no study has been done on its side effects. We tested the safety, feasibility, and effectiveness of cERP in Germany and compared cERP to a historical inpatient control group. Thirty-three patients with OCD were treated with cERP. We assessed severity of OCD (primary outcome: Y-BOCS), depression, global functioning, self-esteem, self-efficacy, experiential avoidance, and quality of life at baseline (t0), two weeks after t0 (t1), and three months after t1 (t2). Side effects were assessed at t1 and t2. The changes in OCD were compared to a matched historical inpatient control group ( n = 33) treated at the same site. The cERP group improved over time, with a large effect size in OCD symptoms and other outcome measures. Improvement of OCD symptoms over treatment was superior in the cERP group compared to the historical control group, with a medium effect size for OCD symptoms. 53–56% of the participants reported at least one side effect (e.g., exhaustion). cERP is safe and effective in the treatment of OCD and can be successfully implemented in Germany. • ERP is highly effective for OCD, though its availability is limited in Germany. • Bergen-4-day treatment (B4DT) is a brief concentrated ERP therapy. • B4DT group was superior compared to a historical control group. • Approximately half of the participants reported at least one side effect. • B4DT can be successfully implemented outside Norway.