Twenty years ago, people diagnosed with autism were relatively rare, and the public’s awareness of the disorder was chiefly limited to Hollywood depictions such as that in the 1988 Academy Award-winning movie Rain Man. Today, many people know a neighbor, friend or classmate who is dealing with autism—prevalence has risen about twenty-fold since 1990. But what’s behind this startling increase? Scientists agree that some of it is due to changes in diagnosis and awareness, but just how much is hotly debated.
“The best papers I’ve seen suggest that there is a genuine increase,” Ricardo Dolmetsch says. “But it’s not as big as it seems. A big, big contribution is societal awareness and changes in diagnostic criteria.”
There have been at least two shifts in diagnosis, says Dolmetsch, an assistant professor of neurobiology at Stanford University. First, some kids who might have once been diagnosed as mentally retarded now are recognized as autistic. Second, children with autism display some of the same characteristics as those who have attention-deficit hyperactivity disorder (ADHD). When the diagnosis is ambiguous, doctors in California tend to diagnose autism rather than ADHD, because the state pays for services (such as behavioral therapy) for autism but not ADHD, Dolmetsch says.
Moreover, the medical establishment’s thinking about what constitutes abnormal behavior has shifted, says Joachim Hallmayer, associate professor of psychiatry and behavioral sciences at Stanford. “There’s no doubt that what we diagnose as autism is different than what we diagnosed 20 years ago.” Autism has been on the rise globally, but the explosion of cases occurs at different times in different countries, which points to a large role for societal awareness, Hallmayer says.
Some of the increase is definitely real, though, according to Antonio Hardan. He cites two contributors. More premature babies are surviving, and preemies are at high risk of autism (about 10 percent will develop it), and more couples are having babies when they’re older, which increases the risk of genetic errors that can lead to autism.
Could something in the environment also be a factor? Maybe, the researchers say, but there is little scientific evidence to back any such claim. Despite widespread concerns about a link between pediatric vaccinations and autism, vaccines have been soundly exonerated, they say.
Paula Gani, says her 4-year-old son Marcus, who has a milder form of autism, “is one of those kids who would not have been diagnosed 20 years ago.” But the diagnosis and early intervention he’s received are likely rewriting his future. He made limited eye contact and didn’t engage socially when he was diagnosed two years ago, but “yesterday, we were going out to pizza with another mom and her kid. And he took the other little boy’s hand and started singing ‘The more we get together, together, together . . . ‘,” she recounts. “It’s a huge difference.”
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