By CAROLYN ABRAHAM in The Globe and Mail, Friday, October 18, 2002

The exploding number of children being diagnosed with autism in California cannot be explained by population growth or broader medical accounting, according to a study released yesterday.

Many people have found comfort in the idea that California's recent surge of autism cases -- resembling trends in several countries, including Canada -- are artificially inflated by immigration and broader diagnostic practices over the past decade.

But a statewide $1-million (U.S.) study undermines that view. The project adds the disturbing dimension that autism cases increasing elsewhere reflect a genuine increase in a disorder once considered rare. 

The project was funded by the California government and the Medical Investigation of Neurodevelopmental Disorders Institute at the University of California, Davis.

"We sense there has been a real increase, but like everyone else, we don't know why, and I don't think this finding is isolated to California," said Margaret Whelan, executive director of the Geneva Centre for Autism in Toronto.

Researchers at the University of California's Children's Hospital conclude that although medical practices, misdiagnoses and population growth are not fuelling the trend, autism cases -- with no apparent reason -- are increasing.

Cases of autism registered with the California Department of Developmental Services increase by an average of nearly 400 every three months, most of them children. From 1983 to 1995, the state's caseload ballooned more than 200 per cent, though the population increased only 20 per cent.

Autism is a complex neurological disorder that profoundly impairs abilities to communicate, socialize, respond to emotion or express it. Those affected often engage in repetitive and sometimes self-injurious behaviours, such as spinning and head banging. Symptoms vary widely in severity, and doctors often refer to it as autistic spectrum disorders.

Although genetics definitely plays a role, some experts suspect environmental factors as a contributor to autism. Controversy rages over the safety of childhood vaccinations, particularly the triple shot against measles, mumps and rubella. But recent studies debunk this link, and this latest study concludes that its sample size is too small to provide answers.

Dr. Byrd, who will discuss the California situation at the Geneva Centre for Autism conference in Toronto next week, said the increasing number of autism cases should place new emphasis on investigating environmental causes.

"This conflicts with the idea that this is largely a genetic disorder. Genetic disorders don't grow by three- or fourfold in this short span of time," Dr. Byrd said.

Researchers based the study on 684 children in two age groups, 7 to 9 and 17 to 19. They compared data between half of those diagnosed with full-syndrome autism and those with retardation, then analyzed any misclassifications.

Other researchers continue to investigate California's autism numbers, including a group backed by the U.S. Centers for Disease Control.

Research groups in Canada are planning similar investigations.

The results of the California study lend credibility to Ron Huff, the California state child psychologist whose numbers were attacked when he identified the autism increase in 1999. His report prompted this latest study of the disease.

Before the release of the results, Dr. Huff said in an interview: "Most people are saying, 'What does it matter if there has been an increase in the numbers?' Unless you're an academic, it doesn't matter. What matters is that it's real to you, and you're in need."