Autism and sniffing pattern may be linked, researchers find

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Ever been through a situation wherein you would have to restrain from breathing owing to the foul odour in a certain place? Ever visiting a garden where the flowers are blossoming at the fullest and the scent is just awesome and you can’t stop breathing in more air? Researchers say that this adjustment that we make to ensure that we breathe in as little or more air as possible based on the surroundings is something that can act as a gauge of whether a person is autistic or not.

According to a study published in Cell Press journal Current Biology, people with autism spectrum disorder (ASD) don’t make the natural adjustment of either letting in more air or letting is as little air as possible like other people do. Autistic children go right on sniffing in the same way, no matter how pleasant or awful the scent.

“The difference in sniffing pattern between the typically developing children and children with autism was simply overwhelming,” says Noam Sobel of the Weizmann Institute of Science in Israel.

Researchers have suggested that non-verbal tests related to smell might serve as useful early indicators of ASD.

There have been previous studies that have indicated that people with autism have impairments in “internal action models,” 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.

For their study, Sobel, Liron Rozenkrantz and their colleagues, enrolled a total of 36 children (18 with ASD and 18 normally developing children) – 34 boys and 2 girls (17 boys and 1 girl in each group) – and made them sniff pleasant and unpleasant odours and measured their responses. The average age of children in the study was 7.

Researchers found that normally developed children adjusted their sniffing within 305 milliseconds of smelling an odour, but children known to suffer from ASD showed no such response.

This particular sniff response was enough to correctly classify them as children with or without a diagnosis of ASD 81 per cent of the time. Moreover, the researchers report that increasingly aberrant sniffing was associated with increasingly severe autism symptoms, based on social but not motor impairments.

The findings suggest that a sniff test could be quite useful in the clinic, although the researchers emphasize that their test is in no way ready for that yet.

“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,” Sobel says. “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.”

The researchers now plan to test whether the sniff-response pattern they’ve observed is specific to autism or whether it might show up also in people with other neurodevelopmental conditions. They also want to find out how early in life such a test might be used. But the most immediate question for Sobel is “whether an olfactory impairment is at the heart of the social impairment in autism.”