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How Do You Diagnose Autism?Michael Savage thinks doctors are getting it wrong.

By Juliet Lapidos
Updated Tuesday, July 22, 2008, at 6:57 PM ET
Michael Savage. Click image to expand.

Children's advocacy groups are demanding that Michael Savage apologize for denigrating autism as the "illness du jour" on his radio program last Wednesday. Savage also attributed the high prevalence of autism and related disorders to faulty diagnoses: "In 99 percent of the cases, it's a brat who hasn't been told to cut the act out." How do doctors spot the disorder?

Surveillance and interviews. According to the American Psychiatric Association's Diagnostic and Statistical Manual, autism is an early onset disorder—it appears before the age of 3—characterized by poor social and communication skills and repetitive behavior. There's no biological test to determine whether a kid has these problems, so pediatricians are encouraged to look out for warning signs—like failure to make eye contact, inability to form relationships with peers, and delayed language skills. If there's cause for a concern, a specialist will typically use a standardized questionnaire to interview the child's parents and teachers: Does little Bobby show interest in people he doesn't know? How does he show interest? Does he prefer solitary play? The specialist will also spend some one-on-one time with the child, noting how he uses toys, responds to images, and whether he engages in conversation.

Per the DSM, clinicians should diagnose a child with autism only if he is judged to have six or more social and linguistic impairments. The threshold is lower for so-called "autism spectrum disorders." A child might be described as having Asperger's if he exhibits some ritualized behavior plus at least two social-interaction impairments—e.g., he can't make friends and has trouble with nonverbal communication like eye contact—but has no significant delay in language acquisition. A child who has severe social interaction or language problems but doesn't quite meet the criteria for autism or Asperger's might end up with a diagnosis of "Pervasive Developmental Disorder Not Otherwise Specified." (For more details on how the DSM classifies these disorders, click here.)

The number of cases of autism-related disorders has skyrocketed in recent years. This past November, Hillary Clinton issued a press release claiming that the diagnosis rate had leapt from one in 10,000 in 1993 to one in 150 in 2007. That's not quite right—the rate was about four in 10,000 as far back as the 1970s and had already climbed to one in 200 in the 1980s. Either way, the numbers have gone up, leading some to wonder whether America is experiencing an epidemic. Some observers have mistakenly blamed mercury in vaccines; others, like Slate's Gregg Easterbrook, say television could be the culprit. Meanwhile, skeptics like Michael Savage hold a "cartel of doctors and drug companies" responsible for creating a panic.

What's certain is that the DSM definition has become more expansive. In the version of the manual from 1968, the word "autism" appears as a symptom of childhood schizophrenia. It only became its own category in 1980, and in 1987 the diagnosis required a finding of eight social and linguistic impairments rather than six. In 1994, the term Asperger's was introduced so doctors could diagnose a lesser form of the disorder. Awareness is also affecting the diagnosis rate: Clinicians know what to look for and are encouraged to act quickly when they notice symptoms.

Got a question about today's news? Ask the Explainer.

Explainer thanks Roy Richard Grinker of George Washington University, Ami Klin of Yale University, and Adriana Di Martino of NYU.

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Juliet Lapidos is a Slate assistant editor.
Photograph of Michael Savage by John Storey/AP Photo. Photograph of the baby on Slate's home page from Morguefile.
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