Why Autism Rates Have Soared

The rate at which autism is diagnosed around the world has increased dramatically in just a generation, and researchers studying a comprehensive tracking system in Denmark say they can explain the majority of the uptick: new and improved diagnosis. In the medical journal JAMA Pediatrics, they argue that the huge jump in autism rates essentially isn't real, reports Forbes. More precisely, "the increase is likely more about previously unidentified autistic individuals getting an autism diagnosis than more individuals actually developing autism," writes Tara Haelle. For one thing, the word "autism" hasn't been around terribly long, and until the 1960s it was linked to schizophrenia. Even as recently as the 1980s, it was described as an "infantile" disorder, diagnosed only when symptoms appeared before age 3.

Denmark widened its definition of autism in 1994, and when the nation's health registries started tracking outpatient diagnoses in addition to those admitted to health care facilities in 1995, the autism rate soared. Similar diagnostic changes have occurred in the US, where 1 in 68 kids are diagnosed with the disorder, reports Time. Still, notes the San Francisco Chronicle, the findings account for only 60% of the increase. "I am not saying it explains everything," says the study's author. But it's "important because it shows a large part of the increase has nothing to do with the environment, but rather administrative decisions." (Other research suggests that exposure to high levels of air pollution in utero could raise a child's risk of autism.)