Autism is a highly variable brain disorder characterized by impaired social interaction and communication, and by restricted and repetitive behavior, typically beginning before a child is three years old. Autism affects many parts of the brain although how and why this occurs is not understood.  Symptoms tend to continue through adulthood, although often in more muted form.

 

The number of people known to have autism has increased dramatically since the 1980s, partly due to changes in diagnostic practice; the question of whether actual prevalence has increased is unresolved.

 

Parents usually notice signs in the first two years of their child's life. Although early behavioral or cognitive intervention can help children gain self-care, social, and communication skills, there is no known cure. Not many children with autism live independently after reaching adulthood, though some become successful. An autistic culture has developed, with some individuals seeking a cure and others believing autism should be tolerated as a difference and not treated as a disorder.

 

Contrary to common beliefs, autistic children do not prefer being alone. Making and maintaining friendships often proves difficult for those with autism. 

 

About a third to a half of individuals with autism do not develop enough natural speech to meet their daily communication needs. Differences in communication may be present from the first year of life, and may include delayed onset of babbling, unusual gestures, diminished responsiveness, and vocal patterns that are not synchronized with the caregiver. In the second and third years, autistic children have less frequent and less diverse babbling, consonants, words, and word combinations; their gestures are less often integrated with words. Autistic children are more likely to repeat others' words or reverse pronouns, may have difficulty with imaginative play and with developing symbols into language.