Atypical longitudinal development of speech-evoked auditory brainstem response in preschool children with autism spectrum disorders.

Language impairment is common in children with autism spectrum disorders (ASDs). Previous research has shown that this disability may be, in part, due to atypical auditory processing of speech stimuli. However, how speech sounds are processed in children with ASD remains largely unknown. The present study assessed the developmental pattern of auditory information processing at the level of the brainstem in preschool children with ASD using speech-evoked auditory brainstem response (speech-ABR). Children with ASD (N = 15) and of typical developing (TD) (N = 20), both of preschool age, were enrolled. The speech-ABRs recorded at two different time points (T1 and T2; 9.68 months apart on average) were virtually identical in the TD group. However, in the ASD group, the wave V latency of speech-ABR was significantly shortened and the amplitudes of wave A and C were significantly larger at T2, compared to those recorded at T1 (10.78 months apart on average). Compared to the TD group, the wave V and A latencies were prolonged at T1, whereas the wave E amplitude decreased and wave F latency prolonged at T2. There was a positive partial correlation between the language performance and the wave A amplitude in the ASD group. These results indicate that auditory processing at the subcortical level is well-developed in the TD preschool children, but is immature and abnormal in the children with ASD at the same ages. Thus, aberrant speech processing at the brainstem level may contribute significantly to the language impairment in children with ASD at preschool ages. Autism Res 2019, 12: 1022-1031. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Language impairment is common in children with autism spectrum disorders (ASDs). We investigated the developmental pattern of subcortical auditory processing by monitoring changes in the speech-evoked auditory brainstem response (speech-ABR) over a period of 10 months in preschool children. Our results show that subcortical auditory processing is impaired and immature in children with ASD compared with age-matched, typically developing children. The results suggest that speech-ABR may be used as an objective measure in evaluating the language performance of children with ASD. The results also suggest that aberrant speech processing at the level of the brainstem may contribute significantly to the language impairment in preschool children with ASD.