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"Inside the Autistic Mind" is an article written by Claudia Wallis that appeared in Time Magazine on May 15, 2006.
She tells us that more than 60 years after autism was first described by American psychiatrist Leo Kanner, there are still more questions than answers about this complex disorder. Its causes are still uncertain, as are the reasons for the rapidly rising incidence of autism in the U.S., Japan, England, Denmark and France. But slowly, steadily, many myths about autism are falling away, as scientists get a better picture of what's going on in the bodies and brains of people with autism and as more of those who are profoundly affected, like Hannah, are able to give voice to their experience. Among the surprises:
Dr. Thomas Insel, director of the National Institute of Mental Health (NIMH), which funds much of the nation's autism research, remembers a time when the disorder was rarely diagnosed. "When my brother trained at Children's Hospital at Harvard in the 1970s, they admitted a child with autism, and the head of the hospital brought all of the residents through to see," says Insel. He said, "You've got to see this case; you'll never see it again."
Alas, he was mistaken. According to the Centers for Disease Control and Prevention (CDC), about 1 in 166 American children born today will fall somewhere on the autistic spectrum. That's double the rate of 10 years ago and 10 times the estimated incidence a generation ago. While some have doubted the new figures, two surveys released last week by the CDC were in keeping with this shocking incidence.
No one can say why the numbers have soared. Greater awareness and public health campaigns to encourage earlier diagnosis have surely played a part, since in the past, I many such children were probably labeled retarded or insane and hidden in institutions. But environmental factors may also be contributing to the spike. To get to the bottom of that mystery and others, federal funding for autism research has more than tripled in the past decade, to $100 million, although it pales in comparison with the estimated $500 million spent on childhood cancers, which affect fewer youngsters.
At the Center for Children's Environmental Health and Disease Prevention at the University of California at Davis, toxicologist Isaac Pessah is studying hair, blood, urine and tissue samples from 700 families with autism. He's testing for 17 metals, traces of pesticides, opioids and other toxicants.
In March Pessah caused a stir by releasing a study that showed that even the low level of mercury used in vaccines preserved with thimerosal, long a suspect in autism, can trigger irregularities in the immune-system cells-at least in the test tube. But he does not regard thimerosal (which has been removed from routine childhood vaccines) as anything like a smoking gun. "There's probably no one trigger that's causing autism from the environmental side," says Pessah, "and there's no one gene that's causing it."
Indeed, most researchers believe autism arises from a combination of genetic vulnerabilities and environmental triggers. An identical twin of a child with autism has a 60% to 90% chance of also being affected. And there's little doubt that a vulnerability to ASD runs in some families: the sibling of a child with autism has about a 10% chance of having ASD.
Gene scientists working on autism have found suspicious spots on chromosomes 2, 5, 7, 11 and 17, but there are probably dozens of genes at work. "We think there are a number of different autisms, each of which could have a different cause and different genes involved," says David Amaral, research director of the MIND (Medical Investigation of Neurodevelopmental Disorders) Institute, also at U.C. Davis.
Amaral is heading MIND'S efforts to assemble a database of clinical, behavioral and genetic information on 1,800 autistic kids. One goal is to clearly define autism subtypes.
"It's hard to do the genetics if you're talking about four or five different syndromes," says NIMH chief Insel. "Does the presence of seizures define a separate illness? What about the kids who seem to develop normally for the first year and a half and then regress-is that a separate thing?" And what about the large number of autistic kids who have serious gastrointestinal problems and the many with immune dysfunctions-are they distinct subtypes?
Amaral and colleague Judy Van de Water, believe they are onto a major discovery about the origins of at least one type of autism-a strongly familial variety. They have detected aberrant antibodies in the blood of kids from families with a pattern of ASD and, significantly, in mothers with more than one autistic child. "These antibodies are actually raised against proteins in the fetal brain," says Amaral, who recently submitted a paper on the discovery.
The working hypothesis is that these antibodies may alter brain development in ways that lead to autism. If correct, the finding could lead to a maternal blood test and the use of a therapy called plasmapheresis to clear antibodies from the mother's blood. "You get a sense of the excitement," says Amaral, "if you could prevent, say, 20% of kids from getting autism. But we don't want to raise false hopes."
Wallis says whether the cause is maternal antibodies, heavy metals or something else, there is no question that the brains of young children with autism have unusual features.
To begin with, they tend to be too big. In studies based on magnetic resonance imaging (MRI) and basic tape-measure readings, neuroscientist Eric Courchesne at Children's Hospital of San Diego showed that while children with autism are born with ordinary-size brains, they experience a rapid expansion by age 2-particularly in the frontal lobes. By age 4, says Courchesne, autistic children tend to have brains the size of a normal 13-year-old.
This aberrant growth is even more pronounced in girls, he says, although for reasons that remain mysterious, only 1 out of 5 children with autism is female. More recent studies by Amaral and others have found that the amygdala, an area associated with social behavior, is also oversize, a finding Amaral believes is related to the high levels of anxiety seen in as many as 80% of people with autism.
Harvard pediatric neurologist Dr. Martha Herbert reported last year that the excess white matter in autistic brains has a specific distribution: local areas tend to be overconnected, while links between more distant regions of the brain are weak. The brain's right and left hemispheres are also poorly connected. It's as if there are too many competing local services but no long distance.
Wallis says that this observation jibes neatly with imaging studies that look at live brain activity in autistic people. Studies using functional MRI show a lack of coordination among brain regions, says Marcel Just, director of Carnegie Mellon's Center for Cognitive Brain Imaging in Pittsburgh, Pa. Just has scanned dozens of 15- to 35-year-old autistic people with IQs in the normal range, giving them thinking tasks as he monitors their brain activity. "One thing you see," says Just, "is that activity in different areas is not going up and down at the same time. There's a lack of synchronization, sort of like a difference between a jam session and a string quartet. In autism, each area does its own thing."
What remains unclear is whether the inter-connectivity problem is the result of autism or its cause. Perhaps all that excess wiring is like the extra blood vessels around the heart of a person who has suffered a heart attack-the body's attempt to route around a problem. Or perhaps the abnormal growth of the brain has to do with the immune system; researchers at Johns Hopkins have found signs that autistic brains have chronic inflammation. "It's impossible to tell the chicken from the egg at this point," Just says.
Autistic people have been shown to use their brains in unusual ways: they memorize alphabet characters in a part of the brain that ordinarily processes shapes. They tend to use the visual centers in the back of the brain for tasks usually handled by the prefrontal cortex. They often look at the mouth instead of the eyes of someone who is speaking. Their focus, says psychologist Ami Klin of Yale's Child Study Center, is "not on the social allegiances-for example, the longing gaze of a mother-but physical allegiances-a mouth that moves."
Wallis asks, "Do these differences reflect fundamental pathology, or are they downstream effects of some more basic problem?" No one knows, she says. But the fact that early intervention brings better results for children with ASD could be a clue that some of the odd brain anatomy and activity are secondary-and perhaps even preventable. Studies that look at whether early therapy might help normalize the brain are beginning at York University in Toronto, but results are probably years away.