Neural Predictors and Neural Changes Associated With Cognitive Behavior Therapy for Obssesive Compulsive Disorder

Obsessive-compulsive disorder (OCD) is a frequent and disabling disorder. Cognitive-behavior therapy (CBT) is the best treatment option available for OCD, although it achieves optimum results in less than half of the patients. The investigators will investigate the main neural circuits that predict CBT outcome in OCD and the neural changes associated with CBT in two separate randomized controlled trials (RCTs), one in an adult sample and another in a pediatric sample. In this two RCTs, OCD participants will be randomized to either intensive CBT (20 sessions in 1 month) by a experienced clinician or a waiting-list control (WLC) and will be assessed (by a blind assessor) and scanned before and after CBT. Patients will be offered CBT if they have been randomized to the WLC. At baseline, the investigators will also compare OCD patients with a group of healthy controls (HC). Secondary goals of the project include 1) assessing potential differences between children/adolescents and adults in the neural mechanisms involved in CBT for OCD; 2) assess the effectiveness of intensive CBT for children/adolescents and adults.