Israeli scientists hope to sniff out autism

Research suggests measuring olfactory system responses to odors can help diagnose disorder from a very young age

Illustrative photo of a girl smelling flowers in a garden in northern Israel, in 2013. (Flash90)
Illustrative photo of a girl smelling flowers in a garden in northern Israel, in 2013. (Flash90)

A group of Israeli scientists is hoping to use autistic children’s distinct sniffing habits to help doctors diagnose the condition at a much younger age than previously possible.

A study by doctoral student Liron Rozenkrantz and Professor Noam Sobel, both from the Weizmann Institute of Science in Rehovot, suggests that autistic children may be diagnosed by their physical response to particularly pleasant and unpleasant odors.

Titled “A Mechanistic Link between Olfaction and Autism Spectrum Disorder,” the study zeroes in on internal action models (IAMs), brain templates for sensory-motor coordination underlying diverse behaviors.

The researchers compared 18 children with autism spectrum disorders to 18 typically developing children. All subjects were presented with pleasant and unpleasant odors to sniff. They were exposed 10 times to pleasant smells, such as rose or shampoo scents. They were also exposed 10 times to unpleasant odors, such as sour milk or rotten fish.

According to the researchers, a child with normal development characteristics will adjust his breathing when confronted with a particularly alluring scent (breath in deeply) or an exceptionally nasty one (limit breath intake). Children do this with remarkable speed — less than half a second on average. Autistic children, meanwhile, continue to breath normally, no matter the smell.

Professor Noam Sobel of the Weizmann Science Institute in  Rehovot. (Courtesy)
Professor Noam Sobel of the Weizmann Science Institute in Rehovot. (Courtesy)

In their experiment, the researchers were able to identify 17 of the 18 typically developing children and 12 of the 18 children with autism, the study said.

What the statistically impressive experiment (81 percent success in diagnosis) brings to the table is the capability to diagnose children even so young that developmental impairment may not yet be outwardly obvious. The “sniff response” is a “non-verbal, non-task-dependent” method, the scientists wrote in the July 2 issue of Current Biology. The method uncovers a “novel marker implying a mechanistic link between the underpinnings of olfaction and autism spectrum disorder directly linking an impaired IAM with impaired social abilities,” they added.

The test also found that increasingly abnormal behavior when it comes to sniffing pleasant or unpleasant smells was linked with increasingly severe autism symptoms, thus making the test potentially useful not just for ruling for or against a disorder of the autism variety but also on the severity of such a disorder on the autism spectrum.

Prof. Sobel was quoted by the Daily Mail as saying: “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.”

Despite the success of the experiment, researchers emphasize that it is not yet ready to be used as a clinical trial.

Their next project is to test whether the sniff-response pattern they observed is specific to disorders of the autism spectrum or whether it might also show up also in people with other neuro-developmental conditions.

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