About 60% of the increase in the prevalence of autism spectrum disorders has been caused by broader diagnostic criteria and new reporting practices, according to a Danish study published in JAMA Pediatrics. Although the study was of Danish children, some of the findings would apply in the United States as well, a researcher not involved in the study told LiveScience.
“The percentage of children with autism worldwide has increased in recent years, but it’s not clear whether this rise is due mainly to changes in how doctors diagnose autism and report cases, or if there is some factor in children’s environment that is affecting autism rates,” reported LiveScience.
The researchers examined the records for nearly 678,000 children born between 1980 and 1991. “During this period, 3,956 of the children were diagnosed with autism, and most of these cases (95 percent) were reported after 1995,” reported LiveScience. “These changes in reporting practices include a 1994 change in the criteria used to diagnose autism, and also a 1995 change in the way autism cases are recorded in Denmark’s health system.”
(Abstract) Explaining the Increase in the Prevalence of Autism Spectrum DisordersThe Proportion Attributable to Changes in Reporting Practices (Hansen, Stefan N. et al. JAMA Pediatr. Published online November 03, 2014. doi: 10.1001/jamapediatrics.2014.1893)
Autism’s Rise: Researchers Look at Why Cases Are Increasing (LiveScience, November 3, 2014)