Biological Measurement in Toddlers with Autism: Auditory Brainstem Responses in Relation to Autism Symptomology

Background: Neurological underpinnings of autism have long been sought out to shed light on heterogenic presentations of autism symptomology. Auditory brainstem responses (ABRs), a measurement of sound processing, have been considered a biological measurement that may aid in understanding the relationship between neurological mechanisms and autism symptomology. Previous research has reported atypical ABRs in children with autism, characterized by longer wave V latencies. In addition, longer wave V latencies and less consistent ABRs are related to low language levels in children who did not have autism. However, little research has considered the relationship between ABRs and characteristics of autism, such as language levels and sensory processing challenges.

Objectives: The current study aims to characterize the relationship between ABRs and autism symptomology, specifically autism severity, language skills and sensory processing challenges. We extend the understanding of the relationship between ABRs and autism to include toddlers with autism. The study explores (1) the relationship between ABRs and language development in children with autism and (2) addresses whether differences between ABRs are associated with sensory processing challenges in children with autism.

Methods: ABRs were measured for 20 children (6 females) with autism (M=33.5 months, SD=4.82). Autism diagnoses were verified based on Autism Diagnostic Observation Schedule scores (M=20.85, SD= 4.55). ABRs were recorded in response to a click and /da/ stimulus. Wave V latencies and response consistency measures served as ABR outcome measures. The Preschool Language Scales-5 (M=65.6, SD=12.92) and Macarthur-Bates Communicative Development Inventories (M=47.55, SD=71.41) were primary measures of language development. Sensory processing profiles were characterized by summing of scores on two questions specific to sensory processing on the ADOS, yielding a group with greater sensory processing challenges (n=11) and a group with lower sensory processing challenges (n=9).

Results: More consistent responses were positively related to number of Words Understood and Words Produced on the MCDI. However, correlations between ABR measures and ADOS scores as well as measures of language development revealed no significant relationship (see Table 1). Children with greater sensory processing challenges showed numerically longer wave V latencies, when compared to those with lower sensory processing challenges, however no statistically significant relationships were found between these sensory groups for either the click wave V latency (t(19)=-1.04, p=.315) and /da/ wave V latency (t(19)=-1.01, p=.331). Additionally, on average children with greater sensory processing challenges showed less consistent responses, however this group difference did not reach significance (t(19)=.72, p=.480).

Conclusions: The current study furthers the understanding of the relationship between ABRs and autism symptomology by including toddlers with autism. Previously reported atypical ABRs in older children with autism may be a reflection of the neurological impact that autism has on the sound encoding process over time. Atypical ABRs may not yet be apparent in toddlers with autism. Future research should include larger sample sizes as well as more nuanced behavioral measures of sensory processing. Longitudinal approaches should be considered when studying ABRs in children with ASD in order to explore the developmental relationship between ABRs and autism symptomology.