For years, rising autism diagnoses have fueled claims that the disorder is becoming increasingly common. But a major study of more than 62,000 children has found that the underlying rate of autism may have remained remarkably stable all along, even as diagnoses have risen dramatically. Researchers analyzed 12 consecutive birth cohorts comprising 62,081 children born between 1998 and 2010 in South Korea.
Their goal was to answer a longstanding question: does the growing number of autism diagnoses reflect a genuine increase in autism itself, or are health systems simply becoming better at recognizing children who were previously overlooked? The study, which used DSM-5 and was published in JAMA Pediatrics, found that the seven-year cumulative incidence of autism spectrum disorder (ASD) remained stable across all birth cohorts examined. Incidence rates ranged from 1.9 percent to 3.2 percent, while prevalence at age 7 ranged from 2.0 percent to 3.4 percent, with no statistically significant upward trend.
"The biggest misconception in general is that rising recorded prevalence automatically proves an 'autism epidemic,'" lead author Young Shin Kim, MD, Ph.D., told Newsweek. "Prevalence is the proportion of people with autism in a population at a given time." Kim's work in this community started in 2005. When researchers first studied the population, they found many children who met diagnostic criteria for autism but had never received a diagnosis or support services.
Those children were often absent from official counts because they had not yet entered clinical or educational systems. That earlier discovery prompted the team to examine whether autism incidence was changing over time. Instead, they found that the overall rate remained almost identical to the results reported in their landmark 2011 study.
"We were struck by how stable the findings were," Kim said. The changing pattern observed by researchers was how many children had already been recognized. In later birth cohorts, a greater proportion of autistic children had been identified through clinical or educational services before researchers conducted their assessments.
The gap between children already known to services and those newly identified through population screening narrowed substantially, suggesting detection has improved. One group, however, continued to be missed. The researchers found that girls with autism were disproportionately represented among previously undiagnosed children identified through screening.
Extract — continue reading at the source.
