MONDAY, Oct. 5, 2009 (HealthDay News) -- While research has suggested that the prevalence of autism spectrum disorders in American children was about 1 of every 150 children, a new government study estimates that the prevalence is more likely about 1 in every 91 children.
The study, which is published in the October issue of Pediatrics, estimated that 110 of every 10,000 U.S. youngsters will be diagnosed at some point in their lives with an autism spectrum disorder. That currently translates to about 673,000 American children with some form of autism, according to the study.
"I think this is a very important study that says the prevalence of autism spectrum disorders may be even higher than we suspected previously," said Geraldine Dawson, chief scientific officer of Autism Speaks.
"Autism is a major public health challenge, and this study is another call to action that we need to be able to provide care across the lifespan," she said.
Autism spectrum disorders are a group of neurodevelopmental disorders, including autism, Asperger syndrome and pervasive developmental disorder. Severity varies from child to child.
Characteristic behavior includes impaired social interaction, difficulty with communication and repetitive behaviors. Over a lifetime, health-care costs for someone with autism are estimated to be more than $1.6 million, according to the study.
The researchers culled data for the study from the 2007 National Survey of Children's Health, which included more than 78,000 children from across the country, all between 3 and 17 years old.
Parents of 1,412 children reported that a doctor had given their child a diagnosis of autism spectrum disorder. Only 913 parents, however, said their child currently had an autism spectrum disorder.
Of that group, 494 parents classified their child's autism as mild, and 320 parents described it as moderate. Just 90 parents said their child's autism was severe.
Cynthia Johnson, director of the Autism Center at Children's Hospital of Pittsburgh, part of the University of Pittsburgh Medical Center, attributed the increase to better diagnostic criteria and an increasing awareness of autism.
"This is more data that adds to what's already in existence that shows autism spectrum disorders are common," Johnson said.
As to the large percentage of children who were diagnosed with an autism spectrum disorder in the past, but whose parents said they currently were not autistic, Johnson said the reasons behind that finding were not clear.
She theorized, though, that "symptoms may lessen with early intensive services, especially for milder cases."
The authors also suggested that autism might have been considered during the initial diagnosis of a child but later dropped if the child turned out to have another disorder.
"We do know that individuals with autism can have a diagnosis early on and then lose that diagnosis, and we don't know the factors that could explain this," Dawson said. "Is it having received good, early behavioral intervention? Or, is there a group of kids that have better biological outcomes? Or, it may have something to do with how kids get diagnosed at different ages. Maybe as kids develop, they may not be getting the same kind of evaluations."
The study also found that the odds of receiving an autism spectrum disorder diagnosis were four times higher for boys than girls, and that non-Hispanic black and multiracial children were less likely to have an autism spectrum disorder than white children.
The U.S. National Institute of Neurological Disorders and Stroke has more on autism.