Doctor of Philosophy
Health Related Sciences
Dr. Stacey Reynolds, PhD, OTR/L
Dr. Shelly Lane, PhD, OTR/L, FAOTA
Dr. Henry Carretta, PhD, MPH
Dr. Deborah Speece, PhD
Children with autism spectrum disorder (ASD) present with a myriad of diagnostic characteristics and associated behaviors. Secondarily, this population is extremely heterogeneous. Efforts have been made by many disciplines to identify more homogenous subgroups in order to improve both research and clinical outcomes. In occupational therapy, the focus has been on establishing sensory-based subtypes. This dissertation is a compilation of three separate research papers related to sensory-based subtypes in children with ASD.
The first paper is a systematic review on sensory subtyping systems published in the last 12 years. Findings indicate that the majority of subtyping schemes characterize group differences by patterns of sensory responsivity (i.e., hyperresponsivity, hyporesponsivity and sensory seeking). One subtyping scheme has emerged as the most well researched of these, and includes responses to specific sensory domains for four different subtypes. The subsequent two papers presents additional research examining this subtyping system.
The second paper examined neurophysiological response to sensory stimuli between the four subtypes. Salivary cortisol, skin conductance level (SCL) and respiratory sinus arrhythmia (RSA) were used examine neuroendocrine function, parasympathetic and sympathetic nervous system responses. Results indicate that parasympathetic response (as indexed by RSA) may best distinguish subtypes with typical sensory processing versus those with atypical sensory processing. More discrete differences between each of the subtypes hallmarked by different sensory processing differences were less substantial.
The third paper examined functional and adaptive behaviors, in addition to clinical behaviors (psychopathology) in relationship to subtype membership. Subtypes with greater sensory processing dysfunction were found to have poorer communication, socialization and performance of daily living skills. In addition, subtypes with atypical sensory processing characteristics had higher levels of internalizing and externalizing behaviors. Again, certain subtypes were not found to differ significantly from each other on these measures.
Overall findings suggest that current sensory-based subtyping schemes may not fully explain sensory processing differences or the variety of behavioral traits observed in this population. In addition, neurological reactivity patterns may not completely align with these subtype divisions. Stronger statistical differences found between certain subtypes indicates particular sensory processing characteristics may be more impairing and have more clinical relevance than others.
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