BOSTON (ASRN.ORG)- At the far end of the basement playroom, Jack Irzyk, 4, smiles as he bobs up and down to the beat of a popular radio tune. He runs his fingers over the corrugated speaker of his boom box, feeling out the texture; once in awhile, he snaps the tape player open and closed. Alone, with his hand on the radio dial, he's content. "It's easy for him to relate to music," explains his mother, Lea Irzyk. "He can control it—music happens on his own terms."

While Lea was pregnant with her second son, Joe, she noticed that Jack wasn't developing like other boys his age. His language was slow: although he could make sounds representing the entire animal kingdom, at almost 2, he could not say "mama." He was a finicky eater, and the texture of fresh fruits and vegetables provoked a gag reflex. But it was his social skills that led Lea and her husband Bob to believe something wasn't right. While their friends' kids would tear around the house, playing chase, Lea would often find Jack lying on the floor by himself, his eyes fixated on the wheels of his toy train as they spun around and around. Instead of engaging his peers, "he would zone out and just stare at nothing," says Lea. Two months after Joe was born, Jack was diagnosed with a less severe form of classic autism, called Pervasive Developmental Disorder–Not Otherwise Specified, or PDD-NOS. 

Clinicians now view autism as a spectrum of neurological disorders, characterized by deficits in social interaction, impaired language, and/or repetitive or restricted behavior. Called autism spectrum disorders (ASDs), they're the fastest growing set of serious developmental disabilities in the United States. According to the Centers for Disease Control and Prevention, one of every 150 children will receive a diagnosis of the disorder by the time they are 8—a rate 10 times higher than it was in the 1980s. Some attribute this hike to a loosening of diagnostic standards and enhanced screening; others believe there's been a substantial increase in cases.

Sixty years after it was first recognized, there are still more questions than answers about the disorder. But despite the elusiveness of autism's causes, there's a consensus among clinicians that treatment should begin as early in life as possible. Many experts suggest that there's a crucial window of plasticity in the child's developing brain when interventions are most effective. Treatments vary depending on the needs of the child; typically, children undergo a combination of intensive behavioral therapy like Applied Behavioral Analysis (ABA) therapy, in which clinicians teach children basic social skills by breaking them down into the smallest steps possible, and speech and language therapy. 

Lea and Bob dropped everything to get Jack into as many services as possible. "We went through what we call a functioning denial," says Lea. "We didn't want to believe the diagnosis, but we had no time to waste." And then there was the question of their newborn, Joe. Because genetics plays an important role in autism, a sibling of a child with autism has up to a 20 percent chance of developing an ASD. Would Joe have autism as well? And if so, would there be a way to detect it earlier so interventions could begin? 

Charles Nelson, PhD, director of the Laboratories of Cognitive Neuroscience at Children's Hospital Boston, is committed to answering that question. By studying the brain development of babies with a higher risk of autism, like Joe, Nelson hopes to discover early indicators that could be used to identify autism in infants. 

Unlike some serious childhood illnesses, like leukemia, there are no blood tests or scans to detect autism, so doctors are left to diagnose it by observing behaviors. Although children with autism are typically diagnosed around age 3 or 4, researchers have found that subtle symptoms can be detected in children much earlier in life, sometimes even before age 1. In 2007, the American Academy of Pediatrics formally recommended that doctors screen all children for autism at 18 months and 2 years, in a concerted effort to get children into treatment as early as possible. 

But relying on behavioral measures to identify autism is tricky in children that young, and even harder in infants. "There's a fine line between deciding if something is abnormal or just different," says Nelson. Development varies enormously from one child to another, and many of the early signs of autism, like being fussy and difficult to feed, are exhibited in typically developing kids. Some of the telltale behavioral indicators of autism, like not responding to one's name when called, aren't applicable until age 1. "The behavioral repertoire of a young infant is limited," says Nelson. "But that doesn't mean things aren't going on upstairs." 

By using imaging tools to look directly at the brain, Nelson hopes to find subtle indicators of autism long before the disorder manifests behaviorally. "The development of language can be witnessed in an infant's brain long before it is expressed," says Nelson. 

These brain studies are coupled with behavioral studies, using a series of standardized tests. Nelson believes that making an accurate prediction of autism in infants won't hinge on a single behavioral measure or neurological test result, but rather a collection of atypical signs. The infants are videotaped while they play with toys and interact socially, allowing researchers to scrutinize potential clues. Parents also fill out an online diary noting the infants' behavior each week, which they share with the researchers. "The parents might recognize signs of autism in their children before the age of 1, because of their experience with their other child," says Nelson. 

The infants are followed to 36 months of age and the lab tracks which children develop ASDs. Nelson believes that if he can find reliable markers for autism at 6 months, new interventions can be developed. "The term 'intervention' is a misnomer," says Nelson. "If we do it early enough and it's that successful, it might actually be prevention." 

Before infants acquire language skills, most communication is non-verbal, which requires them to decode facial signals. From birth on, babies are naturally inclined to look at and focus on faces. 

"Babies just like faces," says Nelson. But the ability to understand and interpret facial expressions appears to be damaged in many people with autism. Nelson wondered if the infants who would go on to develop autism would exhibit atypical brain activity when shown pictures of faces.

In his lab, infants are shown alternating photos of their mother and a stranger, while sensors lightly placed on the baby's head record their brains' responses; in addition, a specially constructed eye tracker records where the baby looks. Nelson's earlier research with typically developing children found that the picture of the mother elicits a larger brain response (which signals attention) than the picture of the stranger. "We can see within four-tenths of a second that the child has recognized their mother," says Nelson. 

But in examining the brain activity of the high-risk infants, he noticed their brains didn't recognize faces in the same way. They responded more slowly to their mothers' faces, and the area of brain that was activated differed from that of the low-risk infants. 

Another neurological test examines the way babies begin to process language. "One of the hallmarks of autism is a language delay," says Vanessa Vogel-Farley, a research coordinator in Nelson's lab. In normally developing babies, previous research demonstrated that at 6 months old, babies can distinguish sounds in virtually any language, but by 1 year, they can only discriminate sounds in their native language. That specialization to the native language is a normal step in acquiring language, says Vogel-Farley. "The developing infant brain is like a sponge," she says. "It adapts extremely fast to the language it hears every day." As the brain becomes an expert in the native language, it stops being able to understand other languages. Preliminary results show that the brains of high- and low-risk infants respond differently to the language test, but the study hasn't had enough participants to show any conclusive outcomes yet.

Although Nelson emphasizes that it's early in the study, these findings suggest facial processing and language skills may be corrupted at a very early age in children with autism. It's possible that in the future, these crucial growth skills can be tested in babies with a sibling with autism to ascertain if they too will develop the disorder. 

Sitting on the floor, Joe, now 2, plays with his blocks. He picks up a plastic triangle and tries to fit it into a circle-sized opening without success. His mother picks up the circle and deliberately feeds it though the hole with an exclamation of "Pop!" Joe catches on, and imitates her without a pause. According to traditional behavioral measures, Joe does not appear to have autism like his older brother, but he will continue to be part of the study for one more year. Nelson's next step in his research will be to add a genetic component to the project, which should help in creating a more complete picture of autism. "We want to collect genes from the families to add to the imaging and behaviors to create a profile," he says. He will team up with the Children's Hospital Informatics Program (CHIP) to pull the data together in a meaningful way.

After two years of intensive behavioral therapy, Jack is in preschool, where he learns with six other boys with ASDs. Each week, he spends a half hour in a regular classroom so he can model the behavior of his peers. The Irzyks aim to have him fully integrated by kindergarten. "If he's not ready, we're not going to push it," his mom says. 

Organizing and planning Jack's therapies can be time consuming (he has two hours of ABA therapy every weekday, occupational therapy twice a week and speech therapy once a week), but the improvements in his language and social skills are striking. "It's incredible," says Lea. "He's a totally different child now." 

Sometimes, she and her husband imagine what Jack's development could be like had he been diagnosed with autism before age 2. "After treatment began, Jack's development skyrocketed," she says. "We wonder, what if we caught it 6 months earlier? Time is really of the essence."

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