The primary study will include 500 OCD patients who will receive the B4DT. Symptom severity will be prospectively measured before treatment, approximately 10 days after treatment and three months after treatment. Saliva samples will be collected for later extraction of DNA methylation during the first day of treatment, the last day of treatment, and three months after treatment. A substudy will use multimodal magnetic resonance imaging (MRI) before treatment, approximately 10 days after treatment and three months after treatment. The substudy will also 100 patients with social anxiety disorder or panic disorder for DNA methylation and MRI, as well as 50 healthy controls for MRI. Clinical data will be collected from a consent-based quality register (Kvalitetsregister for konsentrerte behandlingsformat).~The aim of the study is to investigate changes in DNA methylation as well as functional and structural brain networks that occur in patients undergoing B4DT, and to correlate these changes with immediate and long-term response to treatment.
Obsessive-compulsive disorder (OCD) and anxiety disorders are common and debilitating conditions which are often chronic when treatment is not provided. International guidelines recommend cognitive behavioral therapy (CBT) as the first-line treatment, and research has shown that CBT can be delivered over a concentrated period of time. The Bergen 4-Day Treatment (B4DT) is an exposure-based treatment which is delivered over four consecutive days. B4DT has been shown to induce rapid and long-lasting remission in around 70% of patients. This provides a platform for studying psychological and neurobiological changes associated with treatment response and non-response. The present study will investigate longitudinal changes in psychological measures and DNA methylation in patients who receive the B4DT, as well as a subset will also undergo multimodal brain imaging.