Previous studies have reported that the majority of children with autism spectrum disorders (ASD) present with behaviors and emotional responses suggestive of sensory modulation dysfunction (Tomchek & Dunn, 2007). Further, distinct profiles of sensory modulation function have been identified within ASD (Ausdereau et al 2012; Lane et al 2010, 2011; Ben-Sasson et al, 2008). Recently, associations have been made between patterns of sensory dysfunction and the core deficits of autism, specifically, repetitive behaviors, ritualism and communication competence (Boyd et al 2010; Lane et al, 2010). Moreover, sensory symptoms have been included in the proposed DSM-V criteria for ASD diagnosis (APA, 2012). A major challenge to efforts to identify effective interventions for individuals with ASD is the heterogeneity of the disorder. Phenotyping is the classification of a disorder based on relevant physical and behavioral characteristics for the purposes of reducing heterogeneity and improving management. A systematic investigation of sensory-based phenotypes in ASD is indicated given the frequency of reported difficulties in this area and evidence of strong associations between sensory dysfunction and specific ASD symptom and behavioral profiles.
This study sought to: 1) confirm the existence of distinct sensory subtypes in a large sample of children diagnosed with ASD and 2) examine the relationship between sensory subtypes and age, IQ, gender, autism severity and diagnosis on the spectrum.
We used a secondary analysis approach of data collected during diagnostic evaluations at a large, Midwestern, hospital-based center for autism services and research. Participants were 228 children diagnosed with an ASD aged between 2-10 years. Sensory symptoms were assessed via parent report using the Short Sensory Profile. Autism severity was calculated via the ADOS Calibrated Severity Score and IQ was measured using either the Mullen Scales for Early Learning or the Stanford-Binet-5. Model-based cluster analysis was used to determine the existence of distinct sensory subtypes. One-way ANOVA with post-hoc tests were used to determine differences between the subtypes on key demographic variables.
Four distinct sensory subtypes were revealed in our study supporting the results of previous reports. The subtypes differed from each other on the basis of severity of symptoms and number and type of sensory modalities affected. The four subtypes are: 1) no sensory impairment (n=84), 2) taste/smell sensitive (n=92), 3) postural inattentive (n=23) and 4) generalized sensory dysfunction (n=29). No significant differences were noted between the groups on the bases of autism severity, diagnosis on the spectrum or gender. The Taste/Smell Sensitive subtype was significantly younger than the other groups at diagnosis and had lower IQ. Age and IQ did not discriminate between the other three subtypes, however.
Our study provides evidence for the utility of sensory features as a means of characterizing meaningful subgroups of children with ASD. Sensory features were able to explain variability in our sample beyond traditional measures of age, autism severity and IQ. Future studies should 1) validate these behavioral subgroupings with biomarkers and 2) investigate the utility of the subtypes in predicting intervention response.
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See more of: Symptoms, Diagnosis & Phenotype