Can autism be diagnosed by a child's sense of SMELL? Children with the disorder continue to sniff a bad odour for longer than those without

  • Children without autism have a sniff response in which they try and limit the flow of air through their nose when they smell something bad
  • But children with the disorder continue to smell the odour
  • New sniff test was accurate in diagnosing autism in 81% of children
  • Increasingly abnormal sniff response was associated with more severe symptoms of autism 

By Madlen Davies for MailOnline

Published: 12:02 EST, 2 July 2015 | Updated: 12:06 EST, 2 July 2015

Autism could be detected in toddlers by getting them to perform a simple 'sniff' test, new research suggests.

People might normally take a big sniff of something they expect to be pleasant, such as a rose, but try and limit the flow of air through their nose when they walk into a foul-smelling public toilet.

Now, researchers have found that people with autism spectrum disorder (ASD) don't make the natural adjustment like other people do.

Autistic children carry on sniffing in the same way, no matter how pleasant or awful the scent.

Most people take a big sniff out of something they expect to be pleasant but stop sniffing when they smell something unpleasant. But scientists discovered children with autism continue to sniff regardless

Most people take a big sniff out of something they expect to be pleasant but stop sniffing when they smell something unpleasant. But scientists discovered children with autism continue to sniff regardless

The findings suggest that non-verbal tests related to smell might serve as useful indicators of autism when youngsters are just a few months old.

This is a much earlier age than the condition can currently be confirmed.

Professor Noam Sobel, of the Weizmann Institute of Science, in Israel, said: 'The difference in sniffing pattern between the typically developing children and children with autism was simply overwhelming.'

He said earlier evidence had indicated that people with autism have impairments in 'internal action models'.

These are the brain templates we rely on to seamlessly coordinate our senses and actions. 

But it wasn't clear if this impairment would show up in a test of the sniff response.

To find out, Professor Sobel and his colleagues presented 18 children with autism and 18 normally developing children with pleasant and unpleasant odours and measured their sniff responses.

The average age of children in the study was seven. 

The researchers found that while children without autism adjusted their sniffing within 305 milliseconds of smelling an odour, the autistic children did not adjust their sniffing.

The difference in sniff response between the two groups was enough to correctly classify them as children with or without a diagnosis of ASD 81 per cent of the time.

The test could help diagnose autism in children when youngsters are just a few months old, much earlier age than the condition can currently be confirmed (file photo)

The test could help diagnose autism in children when youngsters are just a few months old, much earlier age than the condition can currently be confirmed (file photo)

And the researchers also reported that increasingly abnormal behaviour when it comes to sniffing was associated with increasingly severe autism symptoms, based on social but not motor impairments.

The findings suggest that a sniff test could be useful in a clinic setting, although the researchers emphasise their test is not yet ready for that.

Professor Sobel said: 'We can identify autism and its severity with meaningful accuracy within less than 10 minutes, using a test that is completely non-verbal and entails no task to follow.

'This raises the hope that these findings could form the base for development of a diagnostic tool that can be applied very early on, such as in toddlers only a few months old.

'Such early diagnosis would allow for more effective intervention.'

Now the researchers plan to test whether the sniff-response pattern they observed is specific to autism or whether it might show up also in people with other neuro-developmental conditions.

They also want to find out how early in life such a test might be used.

The research was published in the journal Current Biology. 

 

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