Sense of Smell May Help Identify Autism Spectrum Disorder

The sniff test identified cases of autism with 81% accuracy.

Wake up and smell the… autism? New research suggests that a sniff test can help accurately identify and classify people with autism spectrum disorder, specifically those with social impairment.

The study results, published in Current Biology, confirm the previous notion that impairment of internal action models, templates for sensory-motor coordination in the brain, is common in autism spectrum disorder.

Liron Rozenkrantz, MD, of the Weizmann Institute of Science in Israel, and colleagues used a non-verbal, non-task-dependent sniff response test with pleasant and unpleasant odors to test the IAM sniff response of 18 children with autism spectrum disorder and 18 matched, typically developing controls (17 boys, 1 girl in each group, avg. age 7 years).

The researchers found that typically-developing children had a typical, adult-like sniff response within 305 milliseconds of odor onset, while children with autism spectrum disorder showed no change in sniff response regardless of odor valance.

“The difference in sniffing pattern between the typically developing children and children with autism was simply overwhelming,” said study author Noam Sobel, MD.

The difference in sniff test response allowed for accurate diagnosis of autism spectrum disorder 81% of the time, and aberrant sniffing was associated with more severe autism spectrum disorder symptoms, specifically social (r = −0.72, P< 0.001), but not motor impairment (r < −0.38, P> 0.18).

The results point to a novel marker of autism spectrum disorder that links olfaction and autism as well as impaired internal action models with impaired social abilities.

“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 said. “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 plan to further explore the sniff response mechanism to see if it is unique to autism or if it can be applied to other neurodevelopmental disorders. They also plan to explore the effect of age on sniff response, and delve deeper into the relationship between olfactory impairment and social impairment in autism. 


  1. Rozenkrantz L et al. Curr Biol. 2015; doi:10.1016/j.cub.2015.05.048