THE report by the Centers for Disease Control and Prevention that one in 88 American children have an autism spectrum disorder has stoked a debate about why the condition’s prevalence continues to rise.
The C.D.C. said it was possible that the increase could be entirely attributed to better detection by teachers and doctors, while holding out the possibility of unknown environmental factors.
But the report, released last month, also appears to be serving as a lightning rod for those who question the legitimacy of a diagnosis whose estimated prevalence has nearly doubled since 2007.
As one person commenting on The New York Times’s online article about it put it, parents “want an ‘out’ for why little Johnny is a little hard to control.” Or, as another skeptic posted on a different Web site, “Just like how all of a sudden everyone had A.D.H.D. in the ’90s, now everyone has autism.”
The diagnosis criteria for autism spectrum disorders were broadened in the 1990s to encompass not just the most severely affected children, who might be intellectually disabled, nonverbal or prone to self-injury, but those with widely varying symptoms and intellectual abilities who shared a fundamental difficulty with social interaction. As a result, the makeup of the autism population has shifted: only about a third of those identified by the C.D.C. as autistic last month had an intellectual disability, compared with about half a decade ago.
Thomas Frazier, director of research at the Cleveland Clinic Center for Autism, has argued for diagnostic criteria that would continue to include individuals whose impairments might be considered milder. “Our world is such a social world,” he said. “I don’t care if you have a 150 I.Q., if you have a social problem, that’s a real problem. You’re going to have problems getting along with your boss, with your spouse, with friends.”
But whether the diagnosis is now too broad is a subject of dispute even among mental health professionals. The group in charge of autism criteria for the new version of the Diagnostic and Statistical Manual of Mental Disorders has proposed changes that would exclude some who currently qualify, reducing the combination of behavioral traits through which the diagnosis can be reached from a mind-boggling 2,027 to 11, according to one estimate.
Biology, so far, does not hold the answers: there is no blood test or brain scan to diagnose autism. The condition has a large genetic component, and has been linked to new mutations that distinguish affected individuals even from their parents. But thousands of different combinations of gene variants could contribute to the atypical brain development believed to be at the root of the condition, and the process of cataloging them and understanding their function has just begun.
“When you think about that one in 88, those ‘ones’ are all so different,” said Brett Abrahams, an autism researcher at Albert Einstein College of Medicine. “Two people can have the same mutation and be affected very differently in terms of severity. So it’s not clear how to define these subsets.”