Until recently, psychiatrists have mainly been handling these kinds of behavioral changes. "A lot of these kids, before they see me, have been trialed on many different psychotropic drugs to try to relax them, to calm them down," Margolis explained on a Wednesday morning in April, as she sat at her cluttered desk in the gastroenterology research lab at Columbia. "Sometimes they work and sometimes they don't."

Dr. Kent Williams, a pediatric gastroenterologist at Nationwide Children's Hospital in Columbus, Ohio, agrees that many doctors are reluctant to consider other possibilities. "My heart goes out to the parents, because this is a daily struggle," he said. "Some physicians don't know what to do, so they give up."

Margolis, Williams and a handful of doctors across the country take a different approach. Instead of concentrating on the brain, they treat the gut.

Dr. Kara Margolis examines a patient. [Danielle Elliot] Dr. Kara Margolis examines a patient. [Danielle Elliot]

"Many doctors don't recognize that aggressive behavior is not part of autism," Margolis said. "This is really a new field." Research is showing that a common cause of autistic children acting out is simply because they're constipated -- which, from there, can mean they stop sleeping and eating well. They may become aggressive and frustrated because they have no other way of saying that their stomachs hurt.

Approximately one in 88 children in the U.S. has an autistic spectrum disorder. Up to 70 percent of them have gastrointestinal (GI) abnormalities at some point during childhood or adolescence. They are 3.5 times more likely to have constipation or chronic diarrhea than children who are not autistic. For years, parents have tried altering their children's diets to alleviate the issues, often restricting or completely eliminating gluten and dairy. But there is little scientific evidence supporting these dietary changes. Still signs keep pointing back to an underlying biological link between autism and GI issues.

A study published last year in the Journal of Abnormal Child Psychology linked the GI issues with behavior, showing that autistic children who have GI issues often experience extreme anxiety as well as regressions in behavior and communication skills. What's worse, the side effects of the psychotropic drugs that are prescribed to many autistic children may be intensifying the digestive issues. Once the GI issues are treated, aggressive and problematic behaviors sometimes subside.

At her first visit with Michael, Margolis suspected that he was nauseous and constipated, conditions that generally manifest in the area of the stomach where he was scratching. The nausea would explain why he often gagged and salivated during meals. She couldn't take x-rays because he was so hyperactive, but Margolis followed her instincts and treated him for constipation and reflux (gastritis).