A new study suggests that the increasing rate of autism may be largely due to reclassification, in which children with other brain development problems are being included in the headcount.
The CDC recently reported that one in 68 children in the United States have autism spectrum disorder (ASD). The rate has increased by 6 to 15 percent each year from 2002 to 2010.
The cause of autism remains to be a mystery and scientists have been scouring for genetic and environmental data in an attempt to crack it. But is it really the genes or the polluted environment that is contributing to the increasing prevalence of autism? Researchers at Pennsylvania State University argue that the increase could be more likely reclassification.
Santhosh Girirajan, assistant professor of biochemistry and molecular biology and of anthropology at Penn State and the study leader, worked with his colleagues in analyzing the medical data of 6.2 million children enrolled in special education programs between 2000 and 2010.
The analysis showed that the number of children diagnosed with autism more than tripled during the study period. The additional rate includes the children who were originally diagnosed with "intellectual disability."
"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" Girirajan said in a university news release. "The tricky part is how to deal with individuals who have multiple diagnoses because, the set of features that define autism is commonly found in individuals with other cognitive or neurological deficits."
The researchers concluded that the increasing autism rate is more likely due to movements of children from one category to another. They also noticed that autism diagnosis varies per state.
The study was published in the July 22 issue of the American Journal of Medical Genetics.
