Autism spectrum disorder (ASD) is defined by a triad of symptoms: communication, social, and sensory processing deficits. ASD is not the only disorder with sensory processing issues. Researchers have begun investigating the sensory processing differences between individuals with ASD and individuals with sensory processing disorder (SPD). SPD is a catch-all term that describes individuals who are hypo- or hyper-sensitive to sensory input, but who lack the other characteristics of ASD. A new study finds that children with ASD and SPD have some common sensory responses, but that children with ASD have unique difficulties with auditory processing. The findings may help researchers understand the underlying nature of autism.
The researchers gathered data from parent surveys and conducted standard neurological tests of boys aged 8 to 12; 19 of the boys were typically developing, 20 had ASD, and 15 had SPD. To test the boys’ sensory processing abilities, the researchers conducted a battery of auditory and tactile processing tests.
For the auditory tests, the boys wore headphones to listen to different numbers, spoken simultaneously in each ear. The test included variations in the numbers’ tone and pitch, and varying levels of background noise. For the tactile tests, the boys reported whether two prongs at various distances felt like one or two points on their fingers, noted the orientation of plastic mesh on their hands, and drew shapes that researchers traced on the back of their hands.
The auditory tests differentiated the boys with ASD and SPD. Overall, boys with ASD performed worse on the auditory tests than the typically developing boys and the boys with SPD. Children with ASD and SPD who performed worse in auditory processing tended to have more difficulties with language and communication in everyday life.
In the tactile tests, both the boys with ASD and with SPD struggled with the complex task of drawing shapes that the researchers traced on their hands. This may be more related to difficulties interpreting, remembering, and transferring the shape than with sensory processing.
The researchers report that more tests are necessary before they can confirm these sensory processing patterns. For example, testing highly verbal children with ASD or SPD children with central auditory processing disorder could help them pinpoint where language and sensory troubles intersect. The findings are similar to those revealed by recent brain imaging studies and could help resolve questions about whether ASD is a collection of traits or has an underlying structure in the brain.
This research is published in the Journal of the International Neuropsychological Society.
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