Autism is a brain disorder that affects a person's ability to communicate, form relationships with others, and respond appropriately to the external world. People with the condition often exhibit repetitive behavior or focused, obsessive interests. Other characteristics of autism include problems with verbal and nonverbal communication and social interaction. Scientists aren't certain what causes the condition, but it's possible that both genetics and environment play a role. Because there is no cure, treatment focuses on minimizing the effects of the disorder. For many children, autism symptoms improve with treatment and with age.