(This reference: Stewart SE,et al. Obsessive-Compulsive Disorder and OCD-Related Disorders. In: Stern TA, et al, editors. MGH: Comprehensive Clinical Psychiatry. Mosby/Elsevier Publ.; 2008.)
Many researchers have argued that early-onset or childhood OCD may be a distinct type of OCD. Between 1/5 and 1/2 of adults with OCD, developed the disorder in childhood. Childhood-onset OCD has been associated with greater severity and higher rates of compulsions without obsessions. When OCD begins in childhood, other disorders such as tic disorders, (ADHD) attention-deficit hyperactivity disorder, and anxiety disorders are more likely to be present. Also, genetic factors appear to play a larger role in the causes of OCD that onsets in youth.