As always with sudden increases the method of measuring has changed
The number of U.S. school children placed in special education programs due to autism more than tripled from 2000 to 2010, to nearly 420,000. But a new study argues much of that increase likely came as educators swapped one diagnosis for another. The overall percentage of kids diagnosed with a collection of brain development problems that includes autism remained unchanged, suggesting that children who used to be labeled with conditions such as “intellectual disability” were in fact autistic.“If you asked me, ‘Is there a real increase in the prevalence of autism?’ maybe there is, but probably much lower than the reported magnitude,” says Santhosh Girirajan, a geneticist at Pennsylvania State University (Penn State), University Park.In the new study, Girirajan and colleagues combed through data collected in each state for approximately 6.2 million U.S. school children with disabilities who are enrolled in special education programs. The information is collected each year under the federal Individuals with Disabilities Education Act. Based on his or her diagnosis, each child was assigned to one of 13 broader categories, ranging from autism to physical challenges such as blindness.Between 2000 and 2010, the number of children in the autism category more than tripled from 93,624 in 2000 to 419,647 a decade later. Yet nearly two-thirds of that increase was matched by a decline in the rate at which children were labeled as having an “intellectual disability.” The number of kids in that category fell from 637,270 to 457,478.The data indicate that the autism rise is partly the result of students being moved from one category to another, Girirajan says.