title: Enhanced olfactory sensitivity in autism spectrum conditions.
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.
authors.affiliation: Autism Research Centre, Department of Psychiatry, University of Cambridge, Douglas House, 18b Trumpington Road, Cambridge, CB2 8AH UK ; Department of Psychology, University of Bath, Bath, BA2 7AY UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Ashwin
authors.affiliation: Autism Research Centre, Department of Psychiatry, University of Cambridge, Douglas House, 18b Trumpington Road, Cambridge, CB2 8AH UK.
authors.forename: Emma
authors.initials: E
authors.lastname: Chapman
authors.affiliation: Autism Research Centre, Department of Psychiatry, University of Cambridge, Douglas House, 18b Trumpington Road, Cambridge, CB2 8AH UK.
authors.forename: Jessica
authors.initials: J
authors.lastname: Howells
authors.affiliation: Autism Research Centre, Department of Psychiatry, University of Cambridge, Douglas House, 18b Trumpington Road, Cambridge, CB2 8AH UK.
authors.forename: Danielle
authors.initials: D
authors.lastname: Rhydderch
authors.affiliation: Department of Psychology, University of Bath, Bath, BA2 7AY UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Walker
authors.affiliation: Autism Research Centre, Department of Psychiatry, University of Cambridge, Douglas House, 18b Trumpington Road, Cambridge, CB2 8AH UK ; Cambridgeshire and Peterborough NHS Foundation Trust, CLASS Clinic, Cambridge, CB21 5EF UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Baron-Cohen
keywords: Asperger syndrome; Autism; Autistic traits; Olfaction; Sensory hypersensitivity