A recent study in the journal Current Biology has found new information about autism spectrum disorder (ASD) that could possibly lead to diagnosing autism through smell. Researchers from the Weizmann Institute of Science compared a small group of children who had been diagnosed with autism to a group of children who had not been diagnosed with autism. They measured differences in how each group reacted to pleasant and unpleasant smells and discovered that researchers who were unaware of each child’s diagnosis were able to accurately diagnosis ASD 81% of the time based purely on the child’s response to strong smells such as roses or rotten fish. 
For the children without an autism diagnosis, their response time to more distinctive smells was almost immediate with varying nasal airflows based on the type of smell (pleasant versus unpleasant). Children with ASD were also able to perceive the more pungent aromas; however, there was little to no adjustment in their sniffing from smell to smell. In other words, children without autism reacted positively to pleasant smells by increasing their inhaling breaths and negatively to unpleasant smells by decreasing or stopping their nasal airflow, while children with autism did not adjust their breathing.
Researchers also found that the sniff-response of children with autism spectrum disorder is linked to social impairment. While olfactory functions are a “semi-automated response,” as one of the lead researchers Lion Rozenkrantz explains in a New York Times article, the study has revealed that sniff-response is not merely an indication of impaired motor functions. Using other tests that measure motor impairment, the researchers were able to confirm that their study went beyond reflecting physiological conditions. Instead, the researchers believe they can use the sniff-response test to determine the severity of social impairment for children with autism.
Based on this study, researchers suggest that the link between smell and social impairment is significant because smell plays a large role in human interaction. The researchers believe their results are further evidence that olfactory functions and smells help us to “gage and influence the emotions of others,” and that it is impaired smell that not only helps to diagnose, but also contributes to the social behavior of children with autism.
Most importantly, this research provides a possible alternative method for diagnosing autism. While this study is preliminary, with further research the sniff-response test could allow for a nonverbal mode of testing for autism in young children. Having a nonverbal test is significant because it opens up the possibility of early age diagnosis. Because it is nonverbal, and as Rozenkrantz points out, “only requires breathing,” this new finding could change the way autism is detected in the near future. If you have any questions about the connection between smell and autism, please feel free to contact Dr. Stephanie Foster by emailing Stephanie@kidswork.biz.