Autism article

This was in today’s paper in San Diego…
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In medical puzzle, autism rate is up tenfold since 1980s

Wider definitions just part of answer

By Sandra Blakeslee
NEW YORK TIMES NEWS SERVICE

January 1, 2003

Autism is about 10 times as prevalent today as it was in the 1980s, according to the largest study ever in the United States on the problem. Some of the increase is the result of widened definitions of the disorder, researchers say, but the explanation for the rest of the increase is unknown.

The study, conducted in metropolitan Atlanta in 1996, found that 3.4 in every 1,000 children 3 to 10 had mild to severe autism that year. In the late 1980s, 4 to 5 in every 10,000 children were thought to be afflicted.

The higher prevalence rate, described in today’s issue of the Journal of the American Medical Association, is in line with rates found in recent but smaller studies in the United States and abroad in which the autism prevalence was 4 to 6 children in 1,000.

The researchers, from the federal Centers for Disease Control and Prevention, said the prevalence rates they found would mean at least 425,000 Americans under age 18 have some form of autism, including 114,000 children under age 5.

Dr. Marshalyn Yeargin-Allsop, an epidemiologist at the National Center on Birth Defects and Developmental Disabilities, led the study.

Some of the increased prevalence can be explained by changes in the definition of autism, a brain disorder in which normal social interaction is difficult or impossible. In recent years, the definition has been widened to include milder forms of the disorder.

Most experts say they believe autism results from an interplay of genes and unknown environmental factors.

“No strong candidate environmental exposures have been identified,” said Dr. Eric Fombonne, an autism expert at McGill University and Montreal Children’s Hospital in Quebec. “Claims of an association with measles-mumps-rubella immunization have not been borne out by recent studies, and evidence for causal association with other exposures, such as mercury-containing vaccines, is weak,” Fombonne said.

Portia Iversen, the mother of an autistic child and the co-founder of Cure Autism Now, an advocacy group in Los Angeles, called the findings unsurprising. “We are in the midst of an autism epidemic in this country,” Iversen said. “We need the government to step in and take emergency action.”

Yeargin-Allsop said the researchers surveyed schools, clinics, doctors, nonprofit programs and other places that autistic children might have gone for services in 1996. Studies that look at autistic children in just one setting, such as special clinics, tend to find lower prevalence rates, she said.

Experts reviewed the medical records of each child and determined whether autism was diagnosed accurately. They did not examine the children themselves. Out of the 289,456 children 3 to 10 living in the five counties of metropolitan Atlanta in 1996, 987 had mild to severe autism, giving a prevalence rate of 3.4 per 1,000.

Yeargin-Allsop said 18 percent of the children found to have autism in 1996 had never had an accurate diagnosis. Many had been classified as having general developmental difficulties; the higher-functioning children had been missed entirely.

Copyright 2003 Union-Tribune Publishing Co.