The study looked at data from a phone survey of 92,000 parents of children aged 17 and younger in the U.S in 2007 and 2008 and found that one-third of children who had ever been diagnosed with an autism spectrum disorder no longer had the diagnosis at the time their parents were surveyed.
The research, led by Dr Andrew Zimmerman from Massachusetts General Hospital for Children, also noted that past studies have found some youngsters with an autism spectrum disorder diagnosis eventually lose it and are no longer considered autistic.
The researchers found that 1,366 parents said their child had a past or current diagnosis of an autism spectrum disorder and in 453 of those cases, the parents said their children no longer had the disorder or diagnosis.
They did find, however, that children with a learning disability or delayed development were more likely to continue to be classed as autistic, as were older children who also suffered from epilepsy and anxiety. They also reported that autism tends to go hand in hand with other mental and behavioural disorders.
Other experts are skeptical as to whether correctly-diagnosed children can grow out of the disorder, with Professor Johnny Matson of Louisiana State University telling Reuters: "When you're autistic, you're autistic. It's a very stable condition."
Dr Zimmerman however claims that recognising autism early and starting treatment can increase the likelihood for real, lasting improvement.
He said: "It's not unusual to see a child start out with more severe autism and then become more moderate and even mild as the years go by. A lot of the kids are improving, and we don't really know why, except we know there's a lot of moldability of the developing brain.
"We think that earlier treatment is essential and there are reasons to think that we can improve the kids. I'm very optimistic.'
The study is published in the journal Pediatrics.
What do you think? Has your child 'grown out of' an autism diagnosis?
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