Autism is a behavior disorder, characterized by an impairment in social communication, social interaction, and social imagination. A U.S. study of autism has found that about one in 150 American children has autism.
Those with autism often have a restricted range of interests and display repetitive behaviors and mannerisms, along with altered reactions to the everyday environment.
The new numbers are based on the largest, most convincing study done so far in the United States, and trump previous estimates that placed the prevalence at 1 in 166.
The difference means roughly 50,000 more children and young adults may have autism and related disorders than was previously thought. US government scientists declined to call the results a complete surprise: The new estimate is on the high end of a prevalence range identified in other recent studies, they said. But one advocate said the study should cause policy-makers and the public to revise how they think of autism.
The new research involved an intense review of medical and school records for children and gives the clearest picture yet of how common autism is in some parts of the country, CDC officials said. The results suggest 560,000 children and young adults have the autistic condition.
Autism is a complex disorder usually not diagnosed in children until after age 3. It is characterized by a range of behaviors, including difficulty in expressing needs and inability to socialize. The cause is not known.
Although autism is behaviorally defined, it is now well recognized to be the endpoint of several organic causes. These include prenatal problems such as rubella (measles) infection, untreated metabolic disorders, and anticonvulsant medication taken during pregnancy, as well as postnatal infections such as encephalitis. A specific medical cause is found in only a minority of people with autism (6?10%, depending on the study). Epilepsy occurs more commonly than usual in patients with this disorder and was one of the early indications that this was a neurobiological problem and not one caused by parental behavior or the environment.