ill eat the enzyme three times a day - they sprinkle the tasteless powder over their food - for 90 days. After that time period, parents can opt to give their children the enzyme for up to a year, whether they were in the treatment group or the placebo group.
Researchers will use interviews with parents and other behavioral tests to assess whether there are any changes in the children's symptoms.
"The treatment is enormously simple, but finding it out wasn't simple at all," said Joan Fallon, chief executive of Curemark, who is a pediatric chiropractor who works with autistic children. "Is it theoretical? Yes. But we hope the trials will give some benefit to a subgroup of children. And we hope our trials will make other researchers look at the physiology of the disorder."
Fallon took an interest in enzyme replacement when she saw that many autistic children had diets heavy in carbohydrates - french fries and pastas and breads - but hardly any protein. These kids may avoid protein because they're missing the enzyme to help them digest it.
That enzyme helps the body break down proteins in a process that produces certain amino acids, which are important for brain development and communication between brain cells. So some autistic kids aren't eating enough protein to begin with, and what protein they do eat isn't being digested properly. The idea is that those missing amino acids may be a cause of autism.
At least anecdotally, doctors seem to agree that gastrointestinal problems are common among autistic children. And many parents have reported - again, anecdotally - that dietary changes help improve symptoms of autism.
So it's possible that giving the enzyme to children who are missing it will help some autistic kids, doctors say. At the very least, it's worth testing, especially since the enzyme itself is unlikely to have any side effects, some researchers say.
"I do think there is a subgroup of kids who have these gastrointestinal symptoms or some difficulty digesting proteins, who may have that relate somewhat to autism," said Dr. Robert Hendren, director of child and adolescent psychiatry at UCSF. "We're always thinking about what else we can try. What else we can do that might help these kids. We have a responsibility to leave no stone unturned."
Much of the research into treatments for autism is based on anecdotal evidence, Hardan said. Doctors often hear of reports from parents who try one trick or another to help ease symptoms in their children, and if something sounds promising, they'll test the treatment in a scientific study.
"I meet with a lot of parents, and they support our research. But some of them, they want something this afternoon, not tomorrow," Hardan said. "And I understand that, it's very frustrating. But that's science. It takes time."
What is autism?
Autism, which usually appears before age 3, is one of a group of developmental problems that generally affect three key areas: social interaction, language and behavior. While there is no cure, early treatment can make a difference.
Causes: Autism has no single, known cause and probably has many. These may include genetic problems that can make a child more susceptible to the disorder or worsen symptoms. Environmental factors may also contribute.
Symptoms: Children with autism show unique patterns of behavior, but common symptoms include delayed development, poor eye contact, failure to hear others, resistance to close contact and unawareness of others' feelings.
Source: Mayo Clinic