Obsessive-Compulsive Disorder

This chapter aims to be of use to clinicians and scientist alike with an interest in understanding the most recent findings in the diagnosis, neuroscience, and treatment of obsessive-compulsive disorder (OCD). The focus is not only on the specific features of OCD but to highlight some of the important similarities and differences between OCD and the related disorders. One of the most significant changes recently is that OCD is no longer classified as an anxiety disorder, but, rather, is placed in its own diagnostic classification of obsessive-compulsive and related disorders (OCRDs). These related disorders include body dysmorphic disorder (BDD), hoarding disorder (HD), trichotillomania (hair-pulling disorder), and excoriation (skin-picking disorder). Expansions of research in the neuroscience, genomics, and clinical features, which are outlined in this chapter, highlight both shared features and important differences between these related disorders. These distinctions have important impacts on treatment because these related disorders can appear as comorbid with OCD but they can also appear without OCD. Other comorbid disorders with OCRDs including bipolar and depressive disorders, psychotic disorders, other anxiety disorders, and substance use disorders are also highlighted.