Autism is a disorder of neural development characterized by impaired social interaction and communication, and by restricted and repetitive behavior.
These signs all begin before a child is three years old. It is a highly variable neurodevelopmental disorder that first appears during infancy or childhood, and generally follows a steady course without remission. Basically, Autism affects information processing in the brain by altering how nerve cells and their synapses connect and organize; how this occurs is not well understood. The prevalence of autism is about 1–2 per 1,000 people; the prevalence of ASD is about 6 per 1,000, with about four times as many males as females.
The number of people diagnosed with autism has increased dramatically since the 1980s, partly due to changes in diagnostic practice; the question of whether actual prevalence has increased is unresolved. For the year 2010, studies show that if 4 million children are born in the United States every year, approximately 36,500 children will eventually be diagnosed with an ASD.
Assuming the prevalence rate has been constant over the past two decades, we can estimate that about 730,000 individuals between the ages of 0 to 21 have an ASD. It is one of three recognized disorders in the autism spectrum (ASDs), the other two being Asperger syndrome, which lacks delays in cognitive development and language, and Pervasive Developmental Disorder-Not Otherwise Specified (commonly abbreviated as PDD-NOS), which is diagnosed when the full set of criteria for autism or Asperger syndrome are not met.
The effects of this disorder have a huge impact to a certain individual and to the people surrounding him. Children with high-functioning autism suffer from more intense and frequent loneliness compared to non-autistic peers, despite the common belief that children with autism prefer to be alone.
Making and maintaining friendships often proves to be difficult for those with autism. In a pair of studies, high-functioning autistic children aged 8–15 performed equally well as, and adults better than, individually matched controls at basic language tasks involving vocabulary and spelling. Both autistic groups performed worse than controls at complex language tasks such as figurative language, comprehension and inference.