Sensory Subtypes and Heart Rate Variability in Children with Autism Spectrum Disorder

Background:  

Sensory difficulties are a commonly occurring feature of Autism Spectrum Disorders (ASD) and are now included as one manifestation of the ‘Restricted, Repetitive Patterns of Behaviour, Interests, or Activities’ diagnostic criteria.  Their inclusion in the DSM as a diagnostic indicator necessitates a more thorough understanding of the mechanisms of these sensory features to guide assessment and intervention practices.  Currently subtype classification is based on parent-report data and validation of these using objective measures is needed.  Recently it has been reported that sensory features in children with ASD can be classified into sensory subtypes (Lane et al, 2014) and that these subtypes are distinct in the combination of sensory modalities affected and in the severity of symptoms. Based on these subtypes, findings suggest that there are two possible underlying mechanisms of sensory features in ASD: 1) difficulties in sensory reactivity and/or 2) difficulties with multisensory integration.  

Objectives:  

The aim of this study was to examine heart rate variability (HRV), a measure of autonomic nervous system function, in response to a standardized sensory challenge protocol as a function of sensory subtype   We hypothesized that children with ASD classified as sensory reactive will show significantly lower  HRV indicating reduced parasympathetic activity than those classified as having problems in multisensory integration.  This study builds on work showing that HRV during sensory challenges may be a biomarker of ASD (Schaaf, et al, 2013). 

Methods:  

Forty-six children with ASD aged 6-12 years were administered the Sensory Challenge Protocol (McIntosh, et al, 1999). HRV was collected via electrocardiography during baseline and stimulus administration.  General Linear Models were applied to examine differences in HRV by sensory subtype.

Results:  

Preliminary data shows that participants classified as sensory reactive show lower HRV at baseline and during stimulus administration than those in the multisensory group reflecting lower parasympathetic regulation of behaviour during sensory stimuli.  This finding is consistent with Schaaf, et al’s (2013) data but adds greater specificity based on sensory subtype and these findings have relevance in that they  may be useful for tailoring interventions by sensory subtype. 

Conclusions:  

Validation of classification of children with ASD by sensory subtype using objective measures such as HRV will provide data needed to individualize treatment planning based on biologic and clinical performance profiles.

A. E., Molloy, C. A., & Bishop, S. L. (2014). Classification of Children With Autism Spectrum Disorder by Sensory Subtype: A Case for Sensory-Based Phenotypes. Autism Research, 7(3), 322–333. doi:10.1002/aur.1368

Schaaf, R.C., Benevides, T., Leiby, B., Sandecki, J., (2013).  Autonomic Dysregulation during Sensory Stimulation in Children with Autism Spectrum Disorder.  Journal of Autism and Developmental Disorders. 10.1007/s10803-013-1924-6.

McIntosh, D. N., Miller, L. J., Shyu, V., & Hagerman, R. J. (1999). Sensory-modulation disruption, electrodermal responses, and functional behaviors. Developmental Medicine & Child Neurology, 41(09), 608-615.