Autism is usually caused by genetic transfer, and in rare cases, autism is strongly associated with agents that cause birth defects.[6] Controversies surround other proposed environmental causes, such as heavy metals, pesticides or childhood vaccines. The prevalence of autism is about 1–2 per 1,000 people worldwide, and the Centres for Disease Control and Prevention (CDC) report 20 per 1,000 children in the United States are diagnosed with autism as of 2012 (up from 11 per 1,000 in 2008).
Parents usually notice signs in the first two years of their child's life.[12] The signs usually develop gradually, but some autistic children first develop more normally and then regress.[13] Early behavioural, cognitive, or speech interventions can help autistic children gain self-care, social, and communication skills.[12] Although there is no known cure,[12] there have been reported cases of children who recovered.[14] Not many children with autism live independently after reaching adulthood, though some become successful. Characteristics
Autism is a highly variable neurodevelopmental disorder[17] that first appears during infancy or childhood, and generally follows a steady course without respite.[18] Symptoms gradually begin after the age of six months, become established by age two or three years,[19] and tend to continue through adulthood, although often in more muted form.[20] It is distinguished not by a single symptom, but by a characteristic triad of symptoms: impairments in social interaction; impairments in communication; and restricted interests and repetitive behaviour.
Social development
Social deficits