The number of autism cases has increased threefold in 2000-2010. According to a study from the American Journal of Medical Genetics this rise is determined by the fact that classification system which categorizes patients who would have been diagnosed with other intellectual impairment disorder.
The number of autism diagnosis does not necessarily represent the real number of autism cases owing to the fact that autism is very easily confounded with other intellectual disabilities. According to CDC (the United States Centers for Disease Control and Prevention) statistics in 1975 there was only one cause of autism for five thousand people. In 2002 the rates exploded with one cause of autism for 150 people. In 2012 one in 68 people have autism.
The findings of this study suggest that that the prevalence of autism in the special education community has increased by 331 percent between 2000 and 2010. According to the researchers involved in the study this increase is caused by a diagnostic reclassification from commonly met comorbid characteristics like for example intellectual disability.
At the same time intellectual disability cases showed a drop in prevalence of nearly 64.2 percent of the increase reported in autism cases among children with ages between 3 and 18. The researchers also discovered that 75 percent of older children underwent the transition from intellectual disability to autism compared to younger children (only 48 percent). The negative correlations linked to autism and intellectual disability prevalence were different from state to state. This indicates that the distinct state health policies can significantly influence autism classification.
The research was conducted at Penn State University. Researchers from there analyzed data from the United States Individuals with Disabilities Education Act (IDEA) which contained information covering eleven years from approximately 6.2 million children in every year.
The research was led by Santhosh Girirajan who is an assistant professor of biochemistry and molecular biology and of anthropology at Penn State University. The author remarked:
“For quite some time, researchers have been struggling to sort disorders into categories based on observable clinical features, but it gets complicated with autism because every individual can show a different combination of features.”
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