Researchers have developed a sniff response test to diagnose autism, meaning smells can be used to detect Autism Spectrum Disorder (ASD) very early on, like in toddlers only a few days old.

Details of the test have been published in the journal Current Biology. Researchers found that most people in the study adjusted their response to low-magnitude sniffs when presented with an awful smell such as rotten fish. They made the adjustments to avoid smelling the fish in contrast to people with ASD who didn't make these adjustments.

Noam Sobel of the Weizmann Institute of Science in Israel said people with ASD went on to sniff the same smell despite bad scent. He added that the difference in sniffing pattern between the typically developing children and children with autism paves the way for identifying children at risk of autism in early stages.

Internal action models (IAM) trigger body's actions based on sensory experiences. People with ASD usually have a reduced IAM.

A computer-controlled machine was built by Sobel, along with Liron Rozenkrantz and their colleagues to simultaneously deliver odours and measure nasal airflow.

Sobel said the test is completely non-verbal and requires no task to be followed by participants. Less than 10 minutes are taken to identify autism and its severity with meaningful accuracy by using the test.

The findings are encouraging as open doors for developing a diagnostic tool to identify children at risk of autism very early on.

"A good point, as they are saying, is seeing if it's specifically for children with autism or do all children who have any kind of developmental problems exhibit that same pattern?" said Vicki Gibbs Clinical Psychologist and Manager of the diagnostic service at Autism Spectrum Australia.