Autism spectrum disorder (ASD) is a complex developmental disorder that can cause problems with thinking, feeling, language and the ability to relate to others. It is a neurological disorder, which means it affects the functioning of the brain. The effects of autism and the severity of symptoms are different in each person.

Autism is usually first diagnosed in childhood. About one in 68 children is diagnosed with autism according to the Centers for Disease Control and Prevention. Autism spectrum disorder is three to four times more common in boys than in girls. Autism is most often a lifelong disorder, though there are more and more cases of children with ASD who eventually function independently, leading full lives. The information here focuses primarily on children and adolescents.