Alternative Treatment to Reduce Chronicity in OCD: Research Into Brain Response and Adequacy of Treatment

Rationale: Obsessive-Compulsive Disorder (OCD) is a disabling neuropsychiatric disorder that often has a chronic disease course. The standard psychotherapeutic treatment Cognitive Behavioural Therapy (CBT) is unable to redeem about half of all patients and is rejected by many because of its anxiety provoking methods. A promising alternative is the Interference Based Approach (IBA), which appears to be as effective as CBT, and more effective for patients with poor insight. The current study will investigate the proposed IBA non-inferiority to CBT. Furthermore, the neurobiological working mechanisms of both treatments will be investigated. Both treatment modalities are expected to alter activity and connectivity in different functional brain networks. In order to lead the way towards personalized care for OCD patients, clinical and neurobiological predictors of response to treatment will be studied. The eventual aim of this study is to prevent the demoralizing effect of undergoing an ineffective treatment by future prediction of whether an individual patient will respond better to IBA or CBT. This also contributes to solving the costs and waiting times for CBT. Objective: To investigate non-inferiority of IBA compared to CBT and to unravel the neurobiological working mechanisms of both treatment modalities. Study design: Multicentre randomized controlled trial. Study population: 203 adults with a primary diagnosis of OCD and 43 healthy controls, matched on gender, age and educational level. Intervention: The 203 adults with the primary diagnosis of OCD will be divided into the experimental- (IBA) and control intervention (CBT). Healthy controls will not receive an intervention. Main study parameters/endpoints: Clinical measures (e.g. severity of OCD symptoms, disease insight), neurocognitive capabilities (performance on neuropsychological tests), neural correlates on brain structure (i.e. white matter integrity, grey matter volume) and brain function (i.e., activ