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Autism rates rise nationally, but reasons remain unclear

The largest increases in diagnoses were among black children and Hispanic children.

The percentage of American children diagnosed with autism, Asperger syndrome or a related disorder increased by 23 between 2006 and 2008, although the reasons for that increase remains unclear, according to a new report by the Centers for Disease Control and Prevention (CDC).

The report, released Thursday, found that 1 in 88 American children aged eight years old in 2008 had been diagnosed with one of these developmental disorders, which are known collectively as autism spectrum disorders. That was up from 1 in 100 eight-year-olds in 2006 and 1 in 150 in 2002. (Data about eight-year-olds was used because most children with an autism spectrum disorder are diagnosed by that age.)

The data was collected through the Autism and Developmental Disabilities Monitoring (ADDM) Network, which includes 14 different areas of the United States. None of those areas is in Minnesota.

“Some of the increase is due to the way children are identified, diagnosed and served in their local communities, although exactly how much is due to these factors in unknown,” states a summary of the report on the CDC website.

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Indeed, the number of children diagnosed with an autism spectrum disorder varied widely, from 1 in 47 in Utah to 1 in 210 in Alabama.

The largest increases in diagnoses were among black children (91 percent) and Hispanic children (110 percent), probably because screening has improved among those populations, according to the CDC. The researchers also found that five times as many boys as girls were diagnosed with autism: 1 in 54 boys versus 1 in 252 girls.

No data for Minnesota

“The numbers are concerning,” said Maggie Diebel, director of the Minnesota Department of Health’s Community and Family Health Division, in a phone interview Thursday.

“As they say in the report,” she added, “we don’t know the reason behind them.”

The numbers may reflect a real increase in the prevalence rate, she said, or they may reflect the fact that more parents and health-care providers are aware of the signs and symptoms of autism, and thus more children are getting diagnosed.

Minnesota does not currently have an autism surveillance system, although the Health Department is currently investigating what it would take to put such a system in place, Diebel said.

No link to vaccines

Statistics regarding autism have become a controversial topic in Minnesota and elsewhere due to the belief among some parents that childhood vaccines triggered the disorder in their child.

Research has not supported that view, however. Last year, for example, after analyzing more than 1,000 studies, a 16-member committee of experts for the Institute of Medicine reported that it had found no link between childhood vaccines and autism.

“There is no evidence to date that shows any correlation between vaccination and autism,” said Diebel.

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Not getting your child vaccinated, however, puts him or her at greater risk of developing vaccine-preventable diseases, such as measles and whopping cough. These illnesses can be life threatening. Several Minnesota children were hospitalized in 2011 during a measles epidemic, which health officials linked to an unvaccinated child who had acquired the illness while travelling overseas.

Need for more research

As the CDC stresses in its report, scientists are working hard to identify the causes of autism spectrum disorder. Genetics is believed to play a role, but it does not appear to be the only factor. A recent twins study, for example, estimated that only 38 percent of the risk of developing autism can be attributed to genetics. Environmental factors — especially, perhaps, those encountered in the womb — appear to play a larger role in the development of the condition, those researchers concluded.

“Until we have a better handle on what the true rates are, it’s very difficult to try and address causation,” said Diebel.

In the meantime, Diebel and other health officials urge parents to be alert for the signs and symptoms of autism, which include a broad range of social and communication difficulties that start early in childhood.

Any concerns that a child is not meeting developmental milestones should be brought to the attention of the child’s pediatrician. Most delays do not mean that a child has an autism spectrum disorder, but research has shown that early screening, diagnosis and intervention can improve the long-term outcomes for children who do have it.

“With appropriate support, kids really do quite well, said Diebel.

Parents can find more about developmental milestones through the CDC’s “Learn the Signs. Act Early” program.