Sensory Processing Subtypes in Autism: Association with Adaptive Behavior and Autism Severity

Background: It is widely reported that children with autism frequently experience difficulties in sensory processing (Ashburner, Ziviani & Rodger, 2008; Baker, Lane, Angley & Young, 2008; Rogers & Ozonoff, 2005; Tomchek & Dunn, 2007). Direct reports from caregivers and adults with autism reveal a strong perception that negative behaviors associated with sensory processing difficulties are barriers to achieving competence in social participation and communication (Koenig and Kinnealey, 2008). Characteristic patterns of sensory processing in autism, however, are yet to be identified. It is also unclear how sensory processing difficulties contribute to the clinical presentation of the disorder.

Objectives: The aims of this study were twofold: 1) to describe patterns of sensory processing difficulties within a single diagnostic category of autism, and 2) to examine the relationship between sensory processing patterns in this group, adaptive behavior and autism severity.

Methods: Caregivers of children (n=54) with Autistic Disorder aged between 33-115 months were administered the Short Sensory Profile, the Vineland Adaptive Behaviour Scales and the Childhood Autism Rating Scale. Participants were recruited via an autism early intervention program and were either on the wait list, currently enrolled or had completed the program. Correlation, regression and model-based cluster analyses were used to examine the data.

Results: Model-based cluster analysis revealed three distinct sensory processing autism subtypes. These subtypes have been given the preliminary labels of: Sensory-Based Inattentive Seeking, Sensory Modulation with Movement Dysfunction and Sensory Modulation with Taste/Smell Dysfunction. Sensory subtypes were differentiated by the number of sensory domains affected and performance on taste/smell sensitivity and movement-related sensory behavior. Further, nearly all participants (92.6%) exhibited difficulties in auditory filtering. Sensory processing subtypes predicted communication competence and maladaptive behavior. Specifically, those participants with taste/smell dysfunction were noted to have the greatest communication impairment. Greater severity in sensory processing dysfunction was also highly predictive of maladaptive behaviors. Sensory subtypes were not strongly associated with autism severity.

Conclusions: This study found that children with Autistic Disorder exhibit three distinct sensory processing subtypes. These subtypes were found to be predictive of communication competence and maladaptive behaviors. Study findings suggest that consideration of the specific sensory domains affected in autism rather than broad patterns of sensory under- or over-responsivity may guide more targeted and effective intervention strategies. Further, this study lays the foundation for the generation of more specific hypotheses regarding the mechanisms of sensory processing dysfunction in autism and supports the continued use of sensory-based interventions in the remediation of communication and behavioural difficulties in autism.