Inside Autism

POSTED 7 OCT 2004

1. Is autism on the rise?

2. Nature and nurture, but not vaccines

3. The system-making mind

4. Lighting up the brain

Shawn Cody, 15, sits at his desk while classroom activity swirls around him at the Edna Louise Spear elementary school in Port Jefferson, N.Y. For autistic children, who often value order above all else, coping with unpredictable social situations can be an onerous task. AP Photo/Ed Betz

Autism rates - and how they have changed over time -- are notoriously hard to gauge.

In the 1990s, concerned citizens in Brick Township, New Jersey, noticed growing autism rates in local schools and brought the CDC in to investigate. But were they seeing a true increase in autism or were doctors just better at diagnosing it? No one can say. Image: CDC

simple drawn face-sad faceIs autism on the rise?
Was there something in Brick Township's water? In the mid-1990s, residents of the coastal New Jersey community (population 76,000) noticed a troubling trend: the number of children with autism in schools and neighborhoods seemed to be growing. They formed a community action group. They collected data and interviewed local doctors. They wrote to their congressmen.

Boy sits at desk in classroomMeanwhile, epidemiologists at the Centers for Disease Control in Atlanta were fielding calls from doctors reporting the same thing. There seemed to be more children with autism than ever.

At the time, Marshalyn Yeargin-Allsopp was working on a CDC project studying the epidemiology of other developmental disorders, such as mental retardation and cerebral palsy.

"We have a more than 20-year history looking at developmental disorders," says Yeargin-Allsopp. "We collect information on children from three to ten years of age in metro Atlanta. We define a geographical area and try to count every single case. That was 290,000 children aged three to ten years in 1996. Four million people. 40,000 births a year."

In response to doctors' concerns, the CDC incorporated autism into the Atlanta project. Soon after, two congressmen from New Jersey asked the CDC to take a look at Brick Township.

"I'm a developmental pediatrician, and I did my training in the 1970s. We were told that autism was very rare," says Yeargin-Allsopp. "We went to the literature and found that the rate was supposed to be three to four children with autism in 10,000." The CDC sent a team of researchers to Brick Township and started to include autism in the existing Atlanta project. The numbers that returned clashed with expectations.

In Brick Township, the CDC found that four children for every 1,000 had classic autism or autistic disorder, and 6.7 children in 1,000 had a disorder on the "autism spectrum" (we'll get to that later). The findings in Atlanta were similar.

"The numbers were higher than what had been previously reported in the U.S.," says Yeargin-Allsopp. Other reports have added to fears that autism is growing. In 1999, the California Department of Developmental Services reported a 273 percent jump in the number of children being treated for autism between 1987 and 1998 in the state. In 2002, the U.S. Department of Education reported that nationwide autism rates had jumped 556 percent in a decade.

Map shows Brick Township, New Jersey on Atlantic coast.

What's going on? Autism rates -- and how they have changed over time -- are notoriously hard to gauge. There are standardized methods to diagnose the disorder, but this wasn't always the case. Not until the mid-1990s did the medical community reach a consensus. The inconsistency in medical records before then can confound researchers looking for trends.

Because more people, doctors included, are aware of autism and its warning signs now than 20 years ago, the numbers may be misleading. They may simply reflect more diagnoses rather than a rise in incidence. No one can say for sure, at least not yet.

"The definition has changed, the classification system has changed, there's greater recognition now than in the past, and there are services available for children with autism...For all of those reasons, it's very hard to compare the rates from the studies now to the rates from studies ten years ago," explains Yeargin-Allsopp.

What we do know
While epidemiologists puzzle through the numbers, other researchers are asking about biology -- what causes autism, and what does it do to the mind? In the infancy of autism research, the clinic was the best laboratory. Doctors observed their patients and took notes -- recording how people with autism reacted to their families; what their interests were; how, and if, they spoke. The work was critical for developing a clinical definition of autism.

Man sits at piano.
Many people with autism are unusually gifted in subjects like mathematics or music. AP Photo/Jim Lord

More recently, researchers have looked deeper, taking snapshots of the autistic mind at work to uncover faulty circuits. And geneticists have been teasing out the tangled contributions from DNA.

None of this is easy for any complex psychiatric disorder, especially one with so many faces. But a picture is emerging, if through a cloudy window. It reveals much about how the autistic mind works and, some say, about human nature itself.

cartoon, simple head--sad Aloneness and sameness
"Autism is not a disease," says Isabelle Rapin, an autism specialist at the Albert Einstein College of Medicine in New York. "It's a behaviorally defined syndrome, characterized by deficiencies in social ability, language and imagination, and rigidity and repetitive behaviors. It has a very broad range of severity from catastrophic to extremely mild, where you can argue that it overlaps with normality."

The broad nature of autism may be the reason nobody knew about it until 1943, when a doctor named Leo Kanner published a paper describing a disorder characterized by "a powerful desire for aloneness and sameness."

For decades after, autism was seen as the most severe childhood psychiatric condition. Half the children diagnosed with autism did not speak and had below-average intelligence. And they had the hallmark features of autism: poor social skills, narrow imaginations, and obsessive interests in strange topics.

In the 1990s, high-functioning autism (diagnosed when a person shows the features of autism but has average or better intelligence) began to attract attention. By the late 90s, doctors understood that autism is a spectrum of disorders, which are now divided into five categories.

Classic autism: the most severe, and best understood, of the autism spectrum disorders. People with classic autism have trouble interacting with other people and often make repeated, robotic movements. Developmental delays are common.

Asperger syndrome: language develops normally. IQ is generally average or above, typically with uneven abilities.

Disintegrative disorder: marked by normal early development, followed by worsening abilities in language, social interactions and everyday functioning.

Rett disorder: a rare genetic disorder caused by a defect in a single gene. Unlike other forms of autism Rett disorder affects more girls than boys.

Autism spectrum disorder not otherwise specified: The catch-all category. People with PDD have the three classic features of autism but don't fit the other subtypes. Includes high-functioning autism.

So what causes autism? No surprise: It's nature and nurture.

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Megan Anderson, project assistant; Terry Devitt, editor; Sarah Goforth, feature writer for this story; S.V. Medaris, designer/illustrator; David Tenenbaum, feature writer; Amy Toburen, content development executive

©2004, University of Wisconsin, Board of Regents.