From the CDC: Understanding Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a condition characterized by impaired social communication as well as restricted and repetitive behaviors. It is considered a neurodevelopmental disorder because it is associated with neurologic changes that may begin in prenatal or early postnatal life, alters the typical pattern of child development, and produces chronic signs and symptoms that usually manifest in early childhood and have potential long-term consequences. In past decades, autism was conceptualized as a strictly defined set of behaviors, usually accompanied by intellectual impairment. Today, it is recognized as a spectrum, ranging from mild to severe, in which behaviors vary substantially and the majority of children who fall on the spectrum have average to above average intellectual ability. Here, the authors discuss the risk factors for ASD, its epidemiology, common concurrent conditions, evaluation, diagnosis, treatments, and outcomes.