OCD encompasses a relatively frequent anxiety disorder, characterized by repetitive thoughts, impulses, or images (obsessions), and repetitive behaviors or mental acts (compulsions) that cause marked distress. OCD has its onset in late childhood and is present in about 2.5% of the adult population (Nestadt et al. 2009). It has been suggested that OCD is part of the ‘‘obsessive compulsive spectrum disorders’’ (Hollander et al. 1996, 2009). Disorders belonging to this spectrum are thought to share similarities in clinical symptoms, associated features, etiology, underlying neurobiology, and response to treatment.