Exploring sensory phenotypes in autism spectrum disorder

Abstract

Background: Atypical reactions to the sensory environment are often reported in autistic individuals, with a high degree of variability across the sensory modalities. These sensory differences have been shown to promote challenging behaviours and distress in autistic individuals and are predictive of other functions including motor, social, and cognitive abilities. Preliminary research suggests that specific sensory differences may cluster together within individuals creating discrete sensory phenotypes. However, the manner in which these sensory differences cluster, and whether the resulting phenotypes are associated with specific cognitive and social challenges is unclear.

Methods: Short sensory profile data from 599 autistic children and adults between the ages of 1 and 21 years were subjected to a K-means cluster analysis. Analysis of variances compared age, adaptive behaviour, and traits associated with autism, attention-deficit and hyperactivity disorder, and obsessive and compulsive disorder across the resultant clusters.

Results: A five-cluster model was found to minimize error variance and produce five sensory phenotypes: (1) sensory adaptive, (2) generalized sensory differences, (3) taste and smell sensitivity, (4) under-responsive and sensation seeking, and (5) movement difficulties with low energy. Age, adaptive behaviour, and traits associated with autism, attention-deficit and hyperactivity disorder, and obsessive and compulsive disorder were found to differ significantly across the five phenotypes.

Limitations: The results were based on parent-report measures of sensory processing, adaptive behaviour, traits associated with autism, attention-deficit and hyperactivity disorder, and obsessive and compulsive disorder, which may limit the generalizability of the findings. Further, not all measures are standardized, or psychometrically validated with an autism population. Autistic individuals with an intellectual disability were underrepresented in this sample. Further, as these data were obtained from established records from a large provincial database, not all measures were completed for all individuals.

Conclusions: These findings suggest that sensory difficulties in autistic individuals can be clustered into sensory phenotypes, and that these phenotypes are associated with behavioural differences. Given the large degree of heterogeneity in sensory difficulties seen in the autistic population, these sensory phenotypes represent an effective way to parse that heterogeneity and create phenotypes that may aid in the development of effective treatments and interventions for sensory difficulties.

Keywords: ADHD traits; Adaptive behaviour; Autism spectrum disorder; Cluster analysis; OCD traits; Restrictive and repetitive behaviours; Sensory phenotypes; Sensory processing; Social communication.

Fig. 1

Short sensory profile domain Z-scores across the k 2–6 cluster solutions. Negative z-scores are indicative of increased sensory difficulties. Line weights between cluster solutions represent the number of participants remaining/changing clusters across solutions. Error bars indicate standard error of the mean

Fig. 2

Short sensory profile domain raw scores across the five sensory phenotypes: sensory adaptive (SA), generalized sensory difference (GSD), taste and smell sensitive (TSS), under-responsive and sensory seeking (URSS), and movement difficulties with low energy. Error bars indicate standard error of the mean. Green (typical difference), yellow (probable difference), and red (definite difference) classification is based on a comparison with the performance of children without disabilities [10]

Fig. 3

Age (A), IQ (B), and Sex (C) assigned at birth as a function of sensory phenotype (sensory phenotypes: sensory adaptive (SA), generalized sensory difference (GSD), taste and smell sensitive (TSS), under-responsive and sensory seeking (URSS), and movement difficulties with low energy (M/LEW). Error bars indicate standard error of the mean. Note: *indicates significance at p < 0.05

Fig. 4

Adaptive behaviours as a function of sensory phenotype (sensory phenotypes: sensory adaptive (SA), generalized sensory difference (GSD), taste and smell sensitive (TSS), under-responsive and sensory seeking (URSS), and movement difficulties with low energy (M/LEW). Error bars indicate standard error of the mean. Note: *indicates significance at p < 0.05

Fig. 5

Repetitive behaviours, measured by the RBS, and social behaviours, measured by the SCQ, as a function of sensory phenotype. Error bars indicate standard error of the mean. Higher scores are indicative of more repetitive behaviours on the RBS, and more social difficulties on the SCQ. Note: *indicates significance at p < 0.05

Fig. 6

ADHD traits (inattention, hyperactivity) as measured by the SWAN, and OCD traits, as measured by the TOCS, as a function of sensory phenotype. Higher scores on the SWAN are indicative of more ADHD traits, while lower scores on the TOCS are indicative of more OCD traits. Error bars indicate standard error of the mean. Note: *indicates significance at p < 0.05