Autism is a developmental disorder that appears in the first 3 years of life, and affects the brain's normal development of social and communication skills.

Autism is a physical condition linked to abnormal biology and chemistry in the brain. The exact causes of these abnormalities remain unknown, but this is a very active area of research. There are probably a combination of factors that lead to autism.

Behaviors:
"Acts up" with intense tantrums
Gets stuck on a single topic or task (perseveration)
Has a short attention span
Has very narrow interests
Is overactive or very passive
Shows aggression to others or self
Shows a strong need for sameness
Uses repetitive body movements