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. 2014 Nov 20:5:53.
doi: 10.1186/2040-2392-5-53. eCollection 2014.

Enhanced olfactory sensitivity in autism spectrum conditions

Chris Ashwin  1 , Emma Chapman  2 , Jessica Howells  2 , Danielle Rhydderch  2 , Ian Walker  3 , Simon Baron-Cohen  4
Affiliations

Enhanced olfactory sensitivity in autism spectrum conditions

Chris Ashwin et al. Mol Autism. .

Abstract

Background: People with autism spectrum conditions (ASC) report heightened olfaction. Previous sensory experiments in people with ASC have reported hypersensitivity across visual, tactile, and auditory domains, but not olfaction. The aims of the present study were to investigate olfactory sensitivity in ASC, and to test the association of sensitivity to autistic traits.

Methods: We recruited 17 adult males diagnosed with ASC and 17 typical adult male controls and tested their olfactory sensitivity using the Alcohol Sniff Test (AST), a standardised clinical evaluation of olfactory detection. The AST involves varying the distance between subject and stimulus until an odour is barely detected. Participants with ASC also completed the Autism Spectrum Quotient (AQ) as a measure of autism traits.

Results: The ASC group detected the odour at a mean distance of 24.1 cm (SD =11.5) from the nose, compared to the control group, who detected it at a significantly shorter mean distance of 14.4 cm (SD =5.9). Detection distance was independent of age and IQ for both groups, but showed a significant positive correlation with autistic traits in the ASC group (r =0.522).

Conclusions: This is the first experimental demonstration, as far as the authors are aware, of superior olfactory perception in ASC and showing that greater olfactory sensitivity is correlated with a higher number of autistic traits. This is consistent with results from previous findings showing hypersensitivity in other sensory domains and may help explain anecdotal and questionnaire accounts of heightened olfactory sensitivity in ASC. Results are discussed in terms of possible underlying neurophysiology.

Keywords: Asperger syndrome; Autism; Autistic traits; Olfaction; Sensory hypersensitivity.

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Figures

Figure 1
Figure 1
Boxplot showing the mean distance (cm) from the nose at which the control and ASC groups were able to detect the odour in the Alcohol Sniff Test. Larger values reflect greater perceptual sensitivity and error bars represent standard error values.
Figure 2
Figure 2
Scatter plot showing the positive correlation between mean distance of odour detection thresholds (cm) and Autism-Spectrum Quotient scores (0 to 50) for the ASC group.
See this image and copyright information in PMC

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