Autistic disorder is a pervasive developmental disorder characterized by impaired social interaction and communication skills as well as restrictive and repetitive behaviors. It begins in childhood and can last throughout life. While the exact causes are unknown, autism may involve differences in brain structure and function as well as genetic factors. Diagnosis involves evaluation by an autism specialist and is usually made by age 3. Treatment includes early intervention, education programs, family support, and in some cases medication to increase learning and communication abilities and reduce problematic behaviors.