Autism is a brain disorder characterized by social problems, language trouble, and strange, repetitive behaviors -- although there's a wide variation among cases. Many children with autism exhibit baffling behaviors, such as constantly flapping their hands or walking on their toes. They might insist on highly organized or rigid activities, maybe eating only beige foods or constantly carrying around some object, such as a piece of string, says Michael Powers, PsyD, director of the Center for Children with Special Needs in Tolland, Connecticut, and assistant clinical professor of psychology at the Yale University Child Study Center.
And the disorder appears to be more and more common. According to Adrian Sandler, MD, chair of the American Academy of Pediatrics' committee on children with disabilities, it used to be five children in 10,000 who had autism -- now it's four or five in 1,000. Many experts attribute the surge in diagnoses at least in part to greater awareness of this mysterious disorder, which leaves children emotionally bereft. Kids with autism are not only unable to communicate their own thoughts and feelings, but they're also unable to understand the emotions of other people. These children have difficulty putting themselves in someone else's place, says Dr. Powers, and so they won't engage in play and pretending, or respond to others by smiling or nodding.What Causes Autism?
Researchers are working harder than ever to pin down the source of this confusing condition, which was first described in 1943. Initially, experts pegged autism as a psychological condition and blamed poor parenting. But the current thinking is that autism is a disorder of the brain.
By studying the brains of older autistic patients, researchers have discovered an absence of certain nerve cells in different parts of the brain, including the prefrontal cortex, which assigns emotional states to others -- one to understand, say, the difference between a dog that's wagging its tail and one that's snarling. Another impaired area is the amygdala, which allows for emotional learning, such as recalling the meaning behind a facial expression.
Ultimately, autism deprives children of a brain that can easily pull pieces of information together into a unified whole. Instead of seeing the big picture, they see the world as little parts, says Dr. Powers.
That may be why autistic kids cling to these repetitive activities and rituals -- these provide them with a sense of predictability and structure, which is comforting, Dr. Powers explains.
Although researchers aren't sure just what causes the brain's wiring to go awry, studies suggest that autism's roots lie in a person's genes. In a recent study, Karin Nelson, MD, a child neurologist with the National Institutes of Health, and her colleagues compared blood drawn from newborns later diagnosed with autism with the blood of typical infants. The blood of the autistic babies contained vasoactive intestinal peptide, a protein molecule that affects brain development. Researchers are also looking into other possible genetic markers for autism, in hopes that high-risk babies might be identified and treated sooner with current therapies. Dr. Nelson hopes that such knowledge will also lead to the development of new therapies.
Congress recently mandated increased federal funding to examine autism, including the establishment of five research centers. So experts hope to have a clearer picture before long.Why Is It on the Rise?
Researchers aren't just looking into exactly what causes autism -- they're also probing reasons for its recent skyrocketing incidence. Autism is so perplexing and mysterious that experts are beginning to worry that something in the environment may be causing it --- but so far, there's no evidence to support that, says Dr. Sandler.
In fact, many experts say that the rise may not be due to more kids being afflicted with autism, but rather more cases being diagnosed. Today, experts talk not just about autism, but about autism spectrum disorder, which encompasses a greater range of symptoms. It's possible that many of today's kids with autism used to be called something else, such as learning disabled or mentally retarded, says Dr. Powers. Other kids might have been labeled eccentric or unusual -- but not disabled.
For example, kids with Asperger syndrome, sometimes called high-functioning autism, fall under autism spectrum disorder, even though Asperger syndrome tends to be more subtle. A child with Asperger's isn't necessarily antisocial, but he may have difficulty having conversations or reading social cues. However, his language is normal and he may even be precocious, says Dr. Powers. Asperger's is typically diagnosed around age 6 or older. Before that, a child doesn't usually develop the intense interest in a certain subject, like trains or math -- that's the hallmark of Asperger syndrome.