A quarterly publication of the Autism Research Institute
Winter, 2016 | Number 1, Volume 30
Children with autism spectrum disorders (ASD) are impaired at detecting odors, a new study indicates.
Hirokazu Kumazaki and colleagues measured the odor-detecting ability of 23 children with ASD and 20 neurotypical children. All of the children were between eight and 16 years of age. The researchers used a pulse ejection system, which they say resolves problems associated with other techniques.
The researchers exposed the children to two scents: isoamyl acetate (which smells like banana) and allyl caproate (which smells like pineapple). They showed the children three boxes on a touch screen, telling them to touch the boxes and determine which one emitted an odor. When the children touched a particular box in each trial, an odor was emitted.
The researchers exposed the children to stronger odors first, decreasing the strength of the odors until the children successfully completed all trials or failed to detect an odor. They report, “Children with ASD were insensitive to both isoamyl acetate and allyl caproate compared to children with typical development.”
The researchers say that the effects of olfactory disturbances are pervasive. “For instance,” they say, “odor has been shown to have influence on mood as well as autonomic, endocrine, and immune functions. Odors have also been shown to play an important role in inducing emotional reactions, imitating the actions of others, and regulating social interactions.” In addition, they note, olfactory disturbances may contribute to the high rates of food selectivity in autism.
Thus, the researchers say, “insensitivity to some odors might have a tremendous impact on children with ASD” and may explain earlier research findings indicating that an abnormal response to smell is the strongest predictor of social impairment in children with ASD.
The findings of this research are also consistent with an earlier study (see ARRI 2015, Vol. 3) showing that children with ASD did not adjust their sniffing in a normal way when smelling pleasant or unpleasant odors. In that study, longer sniff durations for unpleasant versus pleasant odors correlated with greater social impairments.
“Assessment of olfactory detection thresholds in children with autism spectrum disorders using a pulse ejection system,” Hirokazu Kumazaki, Taro Muramatsu, Takashi X. Fujisawa, Masutomo Miyao, Eri Matsuura, Ken-ichi Okada, Hirotaka Kosaka, Akemi Tomoda, and Masaru Mimura, Molecular Autism, January 2016 (online). Address: Hirokazu Kumazaki, Research Center for Child Mental Development, University of Fukui, 23-3, Matsuokashimoaizuki, Eiheiji-cho, Yoshida-gun, Fukui 910-1193m Japan, [email protected].
