Autism is a developmental disorder characterized by abnormalities in speech and communication, impaired social functioning, and repetitive behaviors and interests. The term "Autism spectrum disorders" or ASD is often used to include autistic disorder, Asperger syndrome and pervasive developmental disorder-not otherwise specified (PDD-NOS). Epidemiological research suggests that ASDs affect at least 60 per 10,000 youth, with estimates as high as 120 per 10,000.