Obsessive-compulsive disorder and comorbid posttraumatic stress disorder

Abstract Posttraumatic stress disorder (PTSD) occurs with relative frequency among patients with obsessive-compulsive disorder (OCD). The two disorders share common features including intrusive thoughts and avoidance behaviors that may overlap and result in a complex clinical presentation. This chapter provides an overview of the background and nature of the comorbidity between OCD and PTSD, including the phenomenon of posttraumatic OCD. Similarities and differences between the cognitive behavior treatments for each disorder are discussed. Treatment considerations based on the functional relationship between OCD and PTSD are illustrated through two case studies.