American Academy of Pediatrics questions autism data
By Sheilah Downey
A study published today in Pediatrics stating that autism rates are affecting 1 in 91 children is raising alarm bells throughout the nation, with some health officials calling it a "public health crisis."
But the statistics in the study are "not as accurate" as an earlier study, says the American Academy of Pediatrics (AAP) in a response to parents.
The autism study data was taken from a telephone survey of 78,000 parents who were asked if they had ever been told their child had autism spectrum disorder (ASD). Based on the parent's reports, the study estimated that the prevalence of the disorder was 110 per 10,000 children or 1 in 91.
Based on the 2007 National Survey of Children's Health, the study found that an estimated 637,000 children ages 3 to 17 had a current diagnosis of the illness.
In a response to the study posted on their website, the AAP says the statistic, 1 in 91 children, is off base because of the way the study was done. The more valid statistic, 1 in 150 children, was taken from the 2002 Autism and Development Disabilities Monitoring (ADDM) Network.
"ADDM data is more accurate than a survey based on parent responses because it confirms the reports of parents and caregivers with a review of the children's medical records," states the AAP letter.
Researchers on the National Survey of Children's Health suggested the numbers may be higher because other disorders, including Asperger and pervasive developmental disorders, were included in the survey.
They also said that public awareness and identification of autism is increasing, leading to higher and earlier diagnoses.
The odds for having autism were four times higher for boys than for girls, said researchers, and white children were more likely than black children to have autism.
Approximately 38 percent of the children who were diagnosed with autism were reported to no longer have the diagnosis.
The AAP said it is possible for children who have been diagnosed with autism to "improve over time."
"Studies have found three percent to 25 percent of children improve to the point they are no longer considered to have autism," states the release. "However, they may continue to have other developmental and behavioral symptoms. The children who improve are likely to have good learning abilities and to have received behavioral therapy."
The AAP also said it is important to have children screened early for the disorder, as early as 18 and 24 months of age. An early diagnosis will lead to effective interventions so that children with autism and related disorders may reach their maximum potential.
Because ASD has so many variables, says the AAP, it has posed "a great challenge to researchers" looking for a cause.
One of the factors that contribute to the condition is genetics, according to the AAP.
"There appear to be multiple genes that predispose an individual for the development of specific symptoms of ASD. Identifiable genetic conditions may account for 10 percent to 20 percent of ASD cases. Siblings of children with ASD have a higher likelihood of being diagnosed with an ASD, or to have isolated symptoms of ASD."
Another factor is environmental factors. There is evidence that prenatal exposure to particular medications (such as valproate), testosterone level, alcohol exposure, and infections (including rubella and cytomegalovirus) may be associated with an increased risk of autism, says the AAP.
Children born prematurely and at very low birth weights are also at higher risk of developing autism.
And while many mothers are worried about vaccines, the AAP that has already been ruled out as a link with autism.
"The one exposure that has been studied is vaccines," says the AAP. "Expert review of the scientific literature finds no causal link between vaccines and autism."
Scientists studying autism and other disorders are examining brain function and are identifying abnormal connectivity between brain cells responsible for imitation, facial expression and sensory processing.
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