Is autism truly on the rise?

Anecdotal reports from schools, doctors, service agencies and parent groups suggests a dramatic increase in children with the neurological disorder. But some experts say that could simply be a result of growing awareness of the condition: More children are being diagnosed because more people know about it.

The new study, done in the Atlanta area, found that 34 of every 10,000 children had autism or a related condition - compared with a rate of 4 to 5 for every 10,000 reported in previous studies conducted elsewhere in the last 20 years.

"The results certainly confirm the impression that many professionals ... have that there are more children who fit the criteria for autism," said Marshalyn Yeargin-Allsopp.

Yeargin-Allsopp is a medical epidemiologist with the National Center on Birth Defects and Developmental Disabilities at the Centers for Disease Control and Prevention.

She headed the study.

"It's clear there are more children being identified for services," she said. "But it could be because services are available, more children are being identified."

The data, published recently in the Journal of the American Medical Association, supports several other recent studies in the United States and Europe that found the rate of autism is higher than once thought. Whether more children are developing autism compared with previous generations is impossible to say, because there are no long-term studies tracking trends.

Also, a broadening of the definition of autism to include milder forms, and a better understanding of the disorder, have led to more children being evaluated and more cases diagnosed.

The Atlanta study, which included children 3 to 10 years old in the five-county metropolitan area in 1996, is part of a larger effort by the CDC to get accurate regional measures of just how big a problem autism is.

Autism is a brain disorder that hinders the ability to communicate, interact and form relationships, and go about day-to-day life. Because the disorder, which ranges from mild to severe, tends to run in families, a strong genetic component is suspected.

But researchers also are looking at other factors, such as environmental influences, that may come into play. Some parents suspect childhood vaccines, but medical scientists are skeptical of that link.

Like the Atlanta study, the studies in Philadelphia and elsewhere won't be able to answer whether the real incidence of autism has increased, since there are no comparable previous studies in those communities. However, they will establish a baseline reading for future research.

"What matters is there are more children out there with autistic disorders than we ever knew and they need services," said Jennifer Pinto-Martin, an associate professor at the University of Pennsylvania School of Nursing and a lead investigator for the CDC study in the Philadelphia area.

The research, done in collaboration with Children's Hospital of Philadelphia, has several components.

The first part will focus on children ages 3 to 8 in the Philadelphia area. Using records from schools, doctors, medical clinics and other official sources, researchers will determine the rate of autism and related disorders.

In another study, being done in several areas around the country, researchers will compare hundreds of autistic children ages 3 to 5 with a matched group who don't have the disorder. The goal is to find out what's similar or different between the groups, which might point to some possible causes for autism.

The debate over whether something is fueling an epidemic of autism was heightened in November with the release of a report in California, which attempted to explain a dramatic increase in the number of children getting services for autism in that state. The report said the increase could not be explained away by a broadening of criteria for the disorder, or the relocation of families to California for the express purpose of getting help for their children. It suggested other factors were at work.

Susan E. Levy, the medical director of the Regional Autism Center at Children's Hospital in Philadelphia and a co-director of the Philadelphia study, said that getting an accurate measure of the scope of autism will lead to something more important:

"Getting a more objective count will help people predict and plan better for what resources are needed," she said.