It may be possible to diagnose autism by giving children a
sniff test, a new study suggests.
Most people instinctively take a big whiff when they
encounter a pleasant smell and limit their breathing when they encounter a foul
smell.
Children with autism spectrum disorder don’t make this
natural adjustment, said Liron Rozenkrantz, a neuroscientist at the Weizmann
Institute of Science in Israel and one of the researchers involved with the
study...
They presented 18 children who had an autism diagnosis and
18 typically developing children with pleasant and unpleasant odors and
measured their sniff responses. The pleasant smells were rose and soap, and the
unpleasant smells were sour milk and rotten fish.
Typically developing children adjusted their sniffing almost
immediately — within about 305 milliseconds. Children with autism did not
respond as rapidly. As they were exposed to the smells, the children were
watching a cartoon or playing a video game.
“It’s a semi-automated response,” Ms. Rozenkrantz said. “It
does not require the subject’s attention.”
Using the sniff test alone, the researchers, who had not
been told which children had autism, were able to correctly identify those with
autism 81 percent of the time.
They also found that the farther removed an autistic child’s
sniff response was from the average for typically developing children, the more
severe the child’s social impairments were.
Liron Rozenkrantz, Ditza Zachor, Iris Heller, Anton Plotkin,
Aharon Weissbrod, Kobi Snitz, Lavi Secundo, Noam Sobel. A Mechanistic Link between Olfaction and
Autism Spectrum Disorder. Current
Biology. Current Biology Publication stage: In Press Corrected Proof
Courtesy of:
http://www.medpagetoday.com/InfectiousDisease/GeneralInfectiousDisease/52454?isalert=1&uun=g906366d4251R5793688u&xid=NL_breakingnews_2015-07-06
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Rozenkrantz L, Zachor D, Heller I, Plotkin A, Weissbrod A, Snitz K, Secundo L, Sobel N. A Mechanistic Link between Olfaction and Autism Spectrum Disorder. Curr Biol. 2015 Jul 20;25(14):1904-10.
ReplyDeleteAbstract
Internal action models (IAMs) are brain templates for sensory-motor coordination underlying diverse behaviors. An emerging theory suggests that impaired IAMs are a common theme in autism spectrum disorder (ASD). However, whether impaired IAMs occur across sensory systems and how they relate to the major phenotype of ASD, namely impaired social communication, remains unclear. Olfaction relies on an IAM known as the sniff response, where sniff magnitude is automatically modulated to account for odor valence. To test the failed IAM theory in olfaction, we precisely measured the non-verbal non-task-dependent sniff response concurrent with pleasant and unpleasant odors in 36 children--18 with ASD and 18 matched typically developing (TD) controls. We found that whereas TD children generated a typical adult-like sniff response within 305 ms of odor onset, ASD children had a profoundly altered sniff response, sniffing equally regardless of odor valance. This difference persisted despite equal reported odor perception and allowed for 81% correct ASD classification based on the sniff response alone (binomial, p < 0.001). Moreover, increasingly aberrant sniffing was associated with increasingly severe ASD (r = -0.75, p < 0.001), specifically with social (r = -0.72, p < 0.001), but not motor (r < -0.38, p > 0.18), impairment. These results uncover a novel ASD marker implying a mechanistic link between the underpinnings of olfaction and ASD and directly linking an impaired IAM with impaired social abilities.