US autism estimate rises to 1 in 68 children

The US government's estimate of autism has moved up again to 1 in 68 US children, a 30 per cent increase in two years.
But health officials say the new number may not mean autism is more common. Much of the increase is believed to be from a cultural and medical shift, with doctors diagnosing autism more frequently, especially in children with milder problems.
"We can't dismiss the numbers. But we can't interpret it to mean more people are getting the disorder," said Marisela Huerta, a psychologist at the New York-Presbyterian Centre for Autism and the Developing Brain in suburban White Plains, New York.

The Centres for Disease Control and Prevention released the latest estimate yesterday. The Atlanta-based agency said its calculation means autism affects roughly 1.2 million Americans under 21.
Two years ago, the CDC put the estimate at 1 in 88 children, or about 1 million.
The cause or causes of autism are still not known. Without any blood test or other medical tests for autism, diagnosis is not an exact science. It's identified by making judgments about a child's behaviour.

Yesterday's report is considered the most comprehensive on the frequency of autism. Researchers gathered data in 2010 from areas in 11 states -- Alabama, Arizona, Arkansas, Colorado, Georgia, Maryland, Missouri, New Jersey, North Carolina, Utah and Wisconsin.

The report focused on 8-year-olds because most autism is diagnosed by that age. The researchers checked health and school records to see which children met the criteria for autism, even if they hadn't been formally diagnosed.
Then, the researchers calculated how common autism was in each place and overall.
The CDC started using this method in 2007 when it came up with an estimate of 1 in 150 children. Two years later, it went to 1 in 110. In 2012, it went to 1 in 88.
Last year, the CDC released results of a less reliable calculation -- from a survey of parents -- which suggested as many as 1 in 50 children have autism.