Physiological and Behavioral Characterization of Sensory Dysfunction in Autism

Background: Unusual responses to sensation or sensory dysfunction (SD) are extremely prevalent (80-90%) in individuals with Autistic Spectrum Disorder (ASD) and present some of the most challenging obstacles by limiting adaptive behaviors and participation in life activities. Nevertheless, SD in autism is poorly characterized, its mechanisms are not well understood, and current practices to address SD lack an adequate theoretical basis and empirical data to support their utility.

Objectives:  This paper presents data describing the physiological and behavioral responses to sensation in 60 well characterized subjects with ASD between 6-9 years of age in comparison to 20  controls.  Relationships between physiological and behavioral variables are reported.  Aims include: 1) Compare physiological activity at baseline and during 7 sensory challenges; 2) Compare behavioral responses to sensation; 3) Evaluate whether physiological reactions predict behavioral responses to sensation and adaptive behavior.

Methods: Sixty well characterized children with ASD were tested during the Sensory Challenge Protocol, a unique laboratory procedure designed to assess autonomic nervous system activity in response to sensory challenges in the auditory, tactile, olfactory, visual and vestibular systems.  MindWare BioLab was used to collect physiological data at baseline and during the sensory challenges. Behavioral responses to sensation were measured by the Short Sensory Profile and the Sensory Processing Measure, and the Vineland Adaptive Behavior Scales-II was used to collect data about adaptive behaviors.  Multiple linear regression will be performed to predict behavioral response to sensation from physiological reactivity after controlling for gender and mental age.

Results: Data collection and analysis will be completed in March 2012.  Pilot findings suggest that children with ASD have different physiological profiles at rest and in response to sensation than typically developing controls.  In addition, there are specific patterns of ANS activity that are related to behavioral responses to sensation.  For example, decreased heart rate variability (a measure of parasympathetic nervous system activity) is expected to be associated with poor adaptive behavior and greater observed sensory dysfunction. 

Conclusions: Objective characterization of SD in ASD may yield important information regarding the type, patterns and severity of sensory features in autism, including their impact on adaptive behaviors.  In addition, this knowledge provides insight into intervention targets for sensory features in ASD.