Olfaction in the autism spectrum (original) (raw)
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Olfactory processing in adults with autism spectrum disorders
Molecular Autism, 2016
Background: As evidenced in the DSM-V, autism spectrum disorders (ASD) are often characterized by atypical sensory behavior (hyper-or hypo-reactivity), but very few studies have evaluated olfactory abilities in individuals with ASD. Methods: Fifteen adults with ASD and 15 typically developing participants underwent olfactory tests focused on superficial (suprathreshold detection task), perceptual (intensity and pleasantness judgment tasks), and semantic (identification task) odor processing. Results: In terms of suprathreshold detection performance, decreased discrimination scores and increased bias scores were observed in the ASD group. Furthermore, the participants with ASD exhibited increased intensity judgment scores and impaired scores for pleasantness judgments of unpleasant odorants. Decreased identification performance was also observed in the participants with ASD compared with the typically developing participants. This decrease was partly attributed to a higher number of near misses (a category close to veridical labels) among the participants with ASD than was observed among the typically developing participants. Conclusions: The changes in discrimination and bias scores were the result of a high number of false alarms among the participants with ASD, which suggests the adoption of a liberal attitude in their responses. Atypical intensity and pleasantness ratings were associated with hyperresponsiveness and flattened emotional reactions, respectively, which are typical of participants with ASD. The high number of near misses as non-veridical labels suggested that categorical processing is functional in individuals with ASD and could be explained by attentiondeficit/hyperactivity disorder. These findings are discussed in terms of dysfunction of the olfactory system.
Olfactory Functions in Adults With Autism Spectrum Disorders
Perception, 2017
Autism spectrum disorders (ASD) are often characterized by atypical sensory behavior (hyper-or hyporeactivity) although evidence is scarce regarding olfactory abilities in ASD; 16 adults with highfunctioning ASD (mean age: 38.2, SD: 9.7) and 14 healthy control subjects (mean age: 42.0 years, SD: 12.5) were assessed in odor threshold, free and cued odor identification, and perceived pleasantness, intensity, and edibility of everyday odors. Although results showed no differences between groups, the Bayes Factors (close to 1) suggested that the evidence for no group differences on the threshold and identification tests was inconclusive. In contrast, there was some evidence for no group differences on perceived edibility (BF 01 ¼ 2.69) and perceived intensity (BF 01 ¼ 2.80). These results do not provide conclusive evidence for or against differences between ASD and healthy controls on olfactory abilities. However, they suggest that there are no apparent group differences in subjective ratings of odors.
Olfactory Detection Thresholds and Adaptation in Adults with Autism Spectrum Condition
Sensory issues have been widely reported in Autism Spectrum Conditions (ASC). Since olfaction is one of the least investigated senses in ASC, the current studies explore olfactory detection thresholds and adaptation to olfactory stimuli in adults with ASC. 80 participants took part, 38 (18 females, 20 males) with ASC and 42 control participants (20 males, 22 females). A subgroup of participants (N = 19 in each group) also conducted an adaptation task. Standardized ''Sniffin' Sticks'' were used to measure olfactory detection levels and adaptation. Adults with and without ASC showed similar olfactory detection thresholds, and similar adaptation to an olfactory stimulus. Since diminished adaptation in ASC has been previously suggested, future research needs to examine adaptation in other modalities as well.
Enhanced olfactory sensitivity in autism spectrum conditions
Molecular Autism, 2014
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.
Research in Autism Spectrum Disorders, 2008
Early olfactory identification deficits have been associated with neurodevelopmental arrest of limbicprefrontal networks. These same networks are implicated in development of autistic-spectrum disorders. We aimed to investigate olfactory identification ability in children with high functioning autism (HFA). Fifteen children with HFA (aged 5-9 years) and 15 age-, gender-and IQ-matched controls (CTL) were compared on their performance on a visual analogue of the University of Pennsylvania Smell Identification Test (UPSIT). The hypothesis that children with HFA would exhibit impaired olfactory identification ability was not supported. However, contrary to the relationship found in the CTLs, smell identification ability was negatively associated with age in HFA. The results suggest some disruption of normal developmental association between olfactory ability and age in HFA. The visual analogue of the UPSIT warrants further investigation to determine its validity and reliability in normal and other clinical populations.
A Mechanistic Link between Olfaction and Autism Spectrum Disorder
Current Biology, 2015
Sniffs are automatically modulatedvigorous sniffs for pleasant and truncated sniffs for unpleasant odors. Rozenkrantz et al. find that children with autism do not modulate sniffs, consequently taking vigorous sniffs of odors such as rotten fish. This language and task-free marker puts sensory-motor coordination at the mechanistic heart of autism.
Olfactory Function Assessment in Italian Subjects with Autism Spectrum Disorder
Chemosensory Perception, 2017
Introduction The olfactory system is associated with several brain areas that might be involved in neurodegenerative processes and neurodevelopmental disorders. For this reason, investigation of the olfactory function plays an important role in the assessment of individuals with autism spectrum disorder (ASD), a neurodevelopmental disorder characterized by an impairment in social communication and by a restricted and repetitive pattern of behaviors. The aim of this study was to examine odor detection threshold, discrimination, and identification in participants with ASD compared to typically developing (TD) controls. Methods Thirty Italian subjects (15 with ASD, mean age 19 ± 0.5 years, and 15 TD controls, mean age 21.7 ± 0.4 years) were evaluated by means of the Sniffin' Sticks extended test through three different parameters, odor detection threshold, discrimination, and identification, and their sum the threshold, discrimination, and identification (TDI) score. Results Our results indicated that the participants with ASD showed an impairment in odor detection threshold and TDI score compared to TD controls. No differences were found in odor identification and discrimination. Participants with ASD were significantly poorer in correctly identifying the following odors: leather, apple, rose, cinnamon, garlic, cloves, and anis. However, they were significantly better than TD controls in correctly identifying the odor of the following fruits: orange, banana, and lemon. Conclusion and Implications Our data provide a comprehensive evaluation of the three olfactory components in an Italian population and confirm an impaired odor detection threshold and TDI score in subjects with ASD compared to TD controls. In conclusion, these results suggest that the Sniffin' Sticks extended test might be a valid tool in early detection and differential diagnosis of neurodevelopmental disorders.
Molecular autism, 2016
Atypical responsiveness to olfactory stimuli has been reported as the strongest predictor of social impairment in children with autism spectrum disorders (ASD). However, previous laboratory-based sensory psychophysical studies that have aimed to investigate olfactory sensitivity in children with ASD have produced inconsistent results. The methodology of these studies is limited by several factors, and more sophisticated approaches are required to produce consistent results. We measured olfactory detection thresholds in children with ASD and typical development (TD) using a pulse ejection system-a newly developed methodology designed to resolve problems encountered in previous studies. The two odorants used as stimuli were isoamyl acetate and allyl caproate. Forty-three participants took part in this study: 23 (6 females, 17 males) children with ASD and 20 with TD (6 females, 14 males). Olfactory detection thresholds of children with ASD were significantly higher than those of TD chi...