The current data show that 1 in 50 children have been diagnosed with autism or a related disorder, such as Asperger's syndrome. The conditions are characterized by difficulty with communication, social functioning and by unusual responses to sensory information.
"Changes in ascertainment of autism spectrum disorders could occur because of changes in autism spectrum disorders awareness among parents or health-care professionals, increased access to diagnostic services, changes in how screening tests or diagnostic criteria are used, or increased special education placements in the community," the authors wrote.
More than one-third of the children in the study were diagnosed in or after 2008, some of whom were "well beyond" the age when autism should be clearly noticeable. The biggest increase was for boys and adolescents ages 14 to 17.
"Much of the prevalence increase from 2007 to 2011-2012 for school-aged children was the result of diagnoses of children with previously unrecognized autism spectrum disorder," the report said.
The parents' reports of diagnoses weren't substantiated through clinical evaluation or medical records, the authors wrote.
Mental health professionals have revised the standards for diagnosing autism in the newest version of their guidelines, the Diagnostic and Statistical Manual of Mental Disorders, which is scheduled to be released next month. Among the changes was a decision to collapse several conditions, including Asperger's syndrome and child disintegrative disorder, into a single autism diagnosis.
Critics have said the elimination of Asperger's as a unique diagnosis could limit access to care for some high- functioning people who previously may have been diagnosed with the syndrome. A study presented in January at a medical meeting suggested that as many as half of the high-functioning patients who had been diagnosed under the previous standards may be missed by the new ones.
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