Autism Experts Bring Insights to Seattle

By Tom Paulson

May 3, 2007

Scientists, parents work together to unravel mystery

In most cases, nobody can say what causes the disorder, sometimes better defined as a spectrum of related disorders, or whether the increasing number of diagnosed cases represents an actual increase or just improved recognition of the disease.

Autism. It is still largely a medical mystery.

More than 900 scientists, physicians, activists and parents from all around the world are gathering in Seattle this week to collaborate on solving that mystery. The sixth International Meeting for Autism Research, which runs Thursday through Saturday, is being held at Seattle Sheraton Hotel. It is not open to the public.

"We're certainly identifying more children with autism," said Geraldine Dawson, co-chairwoman of the conference and director of the University of Washington's Autism Center.

This disorder, largely diagnosed by behavioral patterns and generally described as a developmental disability impairing an individual's ability to communicate or fully engage in social activities, is now thought to occur in one of every 150 births.

Not that long ago, Dawson noted, autism was diagnosed rarely and often at a much later -- in her view, too late -- stage of development.

"We still have a problem with that," she said. Some studies indicate that the average age of a child diagnosed with autism is 7, she said.

"We can have a greater impact with treatment the earlier we can begin it," Dawson said. At the conference, she will present findings from her UW team's work indicating that symptoms of autism can be detected in infants as young as six months.

Others speaking at the meeting include Thomas Insel, director of the National Institute of Mental Health, Allan Jones, chief scientist at the Allen Institute for Brain Sciences and (by video presentation) the president of India, A.P.J. Abdul Kalam.

Most of those attending the conference are likely to be focused on such topics as the genes involved in autism, potential drug targets and better means of diagnosis or treatment.

The public dialogue on autism, however, tends to focus largely on speculation about its cause.

Vaccines, wheat gluten, artificial sweeteners, any number of environmental pollutants and even overexposure to television all have been proposed as potential causes of autism. Though often based on studies of dubious scientific merit, the lack of a firm answer on causation has created a firestorm around those studying the disorder.

The most popular such theory has been that a mercuric preservative, thimerosal, used in some vaccines is the cause of autism. Many powerful people such as Sen. Joe Lieberman, I-Conn., Rep. Dan Burton, R-Ind., and environmental activist Robert Kennedy Jr. have led the charge against thimerosal use in vaccines.

In 2003, when the U.S. Centers for Disease Control and Prevention issued a report concluding that numerous major studies in the United States and Europe could find no link between vaccines and autism, some CDC officials left the public health service after receiving death threats.

The preservative eventually was removed from all routine childhood vaccines, despite the lack of evidence of harm. Vaccines with thimerosal, such as flu vaccines, include a tiny amount of a chemical known as ethyl mercury -- about as much mercury as found in any serving of tuna today. Studies done in Europe have found no decline in autism rates since thimerosal was removed from vaccines.

But just as nature abhors a vacuum, the dearth of answers about autism prompts many to fill in the blanks with their own ideas.

"The increase in the prevalence (diagnosed cases) of autism makes people ask themselves, 'What accounts for this?' " Dawson said. "We don't know if there's been a true increase in cases, but it looks that way to people and they come up with theories."

As the diagnostic tools have improved, allowing for better and earlier detection of autism, the disorder has multiplied into several disorders. Since the 1940s, when it became an actual diagnosis in children, it has continued to split into varieties such as low-functioning autism, high-functioning autism and Asperger syndrome.

For that reason, most researchers today prefer to describe the disorder not in the singular, autism, but as "autism spectrum disorders."

"We now realize we're dealing with a very complex problem," Dawson said. "Most of us think there's more than one cause ... there's not going to be a simple answer here."

Several UW scientists, including Dawson, have participated in recent studies identifying genes involved in autism. Those studies demonstrate, among other things, that the developmental problems that lead to autism begin before birth -- eliminating vaccines or other post-birth experiences as a primary cause.

"We know that some cases of autism are caused by a single genetic mutation," Dawson said. "In perhaps 20 percent of the cases, we can identify the cause. But that means we can't identify causation 80 percent of the time."

Source: Seattle Post Intelligencer