Sniff Test: Could We Diagnose Autism Through Smell?

Researchers are continually learning about autism, a behavioral disorder that's estimated to affect 1 in 68 children. Yet for many children, the initial diagnosis will not come so easily. The symptoms of the behavioral health issue are not always cut and dry for every patient, oftentimes resulting in a latent diagnosis. 

New findings published in the journal Current Biology reveal that people with autism spectrum disorder (ASD) may not distinguish between certain smells as easily as other children, suggesting that non-verbal tests related to smell could potentially serve as useful early indicators of ASD.

"The difference in sniffing pattern between the typically developing children and children with autism was simply overwhelming," said Noam Sobel of the Weizmann Institute of Science in Israel, in a news release. 

For the study, researchers presented 18 children around the age of 7 with ASD and 18 normally developing children (17 boys and 1 girl in each group) with both pleasant and unpleasant odors and measured their sniff responses.

Findings revealed that children without autism adjusted their sniffing within about 305 milliseconds when smelling a certain odor. However, this was not the case for children with ASD. They showed no response to the change in smell. Furthermore, the difference in sniff response between the two groups of kids was enough to correctly classify them as children with or without a diagnosis of ASD 81 percent of the time.

The study results show how a sniff test could be useful in a clinical setting. However, researchers also emphasized that their test is not quite ready 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 concluded. "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 researchers are ready to examine whether the sniff-response pattern they observed during the study may be specific just to autism or other neurodevelopment conditions, as well.

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