(KRT) - A major new government study has found a much higher prevalence of autism than studies done in the 1980s and early 1990s. The findings, though, still don't answer an important question:

Is autism truly on the rise?

Anecdotal reports from schools, doctors, service agencies and parent groups suggest 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 per 10,000 reported in previous studies conducted elsewhere in the last two decades.

"The results certainly confirm the impression that many professionals and others have that there are more children who fit the criteria for autism," said Marshalyn Yeargin-Allsopp. 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 (JAMA), support several other recent studies in the United States and Europe, which found the rate of autism is higher than once thought. Whether there really are more children 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 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. In this area, CDC-funded studies are under way both in New Jersey and in the Philadelphia region to determine the prevalence and to look for possible causes and risk factors.

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. Parents of autistic children often report that their children seemed healthy and normal in the first months or year of life, but then stalled or regressed in their development.

"She was a terrific, great baby, absolutely normal, until she was 2," recalls Julie Clipp of East Greenville, Pa., whose daughter, Casey Ralston, 10, has autism.

Casey attends the Timothy School, a state-approved private facility in Berwyn, Pa., that can barely keep up with the demand for its services.

Applications to the school, which specializes in autism, are booming: For every four or five students accepted, 35 or 40 are turned away, said Judy D'Angelo, director of the school, which has 54 students between ages 5 to 16. She said referrals have increased 20 percent to 25 percent over the last five years.

"I really am concerned that we have so many that we can't help," she said.

Linda Tino of Havertown, Pa., whose 9-year-old son, Gregory, attends the school, said that even with more public awareness of autism, an ordinary outing with her son to a store or restaurant can turn into a nightmare. Because autistic children often make strange vocalizations and repetitive movements, and exhibit other unusual behaviors, they can attract unwanted attention. A huffy mother once told Tino: "If you can't control him, you shouldn't take him out in public."

Like the Atlanta study, the studies under way in Philadelphia, New Jersey and elsewhere also 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 living in the Philadelphia area. Using records from schools, doctors' offices, 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 of children who don't have the disorder. The goal is to find out what's similar or different between the two groups, which might point to some possible causes for autism.

"We will be asking the mothers all kinds of questions," Pinto-Martin said. "What happened to these kids from the time they were conceived until they turned 3 years old?"

In New Jersey, a prevalence study is being done looking at 8-year-olds and using a similar approach to the Philadelphia effort. Children with autism are identified through official records, and then an expert reviews the records to determine whether the diagnosis is correct.

"Since no one ever established a base rate for autism in New Jersey, it will be impossible to say whether we're seeing a change in prevalence or not," said Walter Zahorodny, a researcher at the New Jersey Medical School who is heading the study. Researchers will, however, be able to compare the results with a 1998 CDC-funded study done in Brick Township, N.J., which found a rate of 40 per 10,000 for autism and 67 per 10,000 for autism and related disorders.

New Jersey also is establishing an autism database, by asking parents of children with autism and adults with the disorder to complete a lengthy questionnaire.

"This will give a much greater depth of information," Zahorodny said, and will be used to search for possible causes and risk factors.

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, suggesting other factors were at work.

In an editorial in JAMA accompanying the Atlanta study, Eric Fombonne, an autism expert at Montreal Children's Hospital, said there is little evidence to support the notion that there is an epidemic of autism. He said that while the reported increases in the prevalence of autism reflect changes in diagnostic practices and the availability of services, other factors can't be ruled out.

Susan E. Levy, medical director of the Regional Autism Center at Children's Hospital in Philadelphia and codirector of the Philadelphia study, said getting an accurate measure of the scope of autism will lead to something even more important: "Getting a more objective count will help people predict and plan better for what resources are needed."

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