Many children diagnosed with autism at a young age no longer display symptoms when they are older, new research has found.
The study found one third of children who had been previously diagnosed with autism spectrum disorder, no longer had the diagnosis when their parents were later questioned.
The researchers surveyed 92,000 parents of children aged 17 and younger in the US in 2007 and 2008.
Of 1,366 parents that said their child had been previously diagnosed with autism spectrum disorder, 453 said they no longer had the condition.
The study, published in Paediatrics, revealed that many children with autism have other developmental or psychiatric conditions including learning disabilities, speech delays and attention disorders.
It was found that those with two or more of these conditions were five times more likely to continue to have an autism diagnosis.
The researchers didn’t study the link between autism diagnosis and other developmental or psychiatric conditions. But as some of the symptoms overlap, it is thought that this could lead to confusion and potential misdiagnosis.
For instance, children with hearing problems were less likely to be considered autistic later on. One theory is that the lack of response and engagement associated with impaired hearing could be mistaken for autism.
Lead researcher, Dr Andrew Zimmerman, from Massachusetts General Hospital for Children argues that the study findings should not be put down to misdiagnosis alone.
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,” he said.
“We think that earlier treatment is essential and there are reasons to think that we can improve the kids. I'm very optimistic.”
Past studies have also found some children who originally have an autism spectrum disorder eventually lose that diagnosis and are no longer considered autistic.
Other experts are sceptical about the concept of children 'outgrowing' autism.
Dr Georgina Gomez-de-la-Cuesta, Action Research Leader for The National Autistic Society, told The Huffington Post: "Autism is a serious, lifelong and disabling condition - a child with autism will grow up to be an adult with autism.
"While there is no cure for autism, securing the right support, implementing strategies to manage behaviours and creating the best environment can help manage anxieties and sensory difficulties associated with the condition.
"Although this could lead to improvements in behaviour, the underlying autism remains and can continue to pose very real challenges at every stage in life."
Professor John Matson, at Louisiana State University insists that once someone has been correctly diagnosed with autism, they will always need to take medication: “When you’re autistic, you’re autistic. It’s a very stable condition.”
He said even when symptoms improve, people with autism have to keep getting treatment and work to maintain that progress, it was reported in the Daily Mail.
A recent study discovered a link between autism spectrum disorder and low birth weight while another found a difference in the gut bacteria of autistic children compared to non-autistic children.