Repetitive but Not Interchangeable: Similarities and Differences in the Repetitive Behaviors of Tourette Syndrome, Obsessive-Compulsive Disorder, Tourettic Obsessive-Compulsive Disorder, and Autism Spectrum Disorder.

Repetitive behaviors are the hallmark of many neuropsychiatric disorders, including Tourette syndrome (TS), obsessive-compulsive disorder (OCD), and autism spectrum disorder (ASD). Tics, compulsions, and stereotypies may appear similar and can be difficult to disentangle. This review addresses similarities and differences between these behaviors including clinical presentations, neuroimaging, genetics, and treatment paradigms in order to clarify the relationship between these disorders. The extensive genetic and neurocircuitry-based similarities raise the possibility that in some cases TS and OCD may represent a single neuropsychiatric entity, such as Tourettic OCD, that lies along the impulsive-compulsive spectrum.