Auditory Processing In Young Children with and without Early Signs of Autism Utilizing Event Related Potentials

Background:

The prevalence of sensory processing disorders in children with autism ranges from 69% to 95%. Sensory processing disorders manifest themselves as auditory under-responsiveness and restrictive and repetitive behaviors and are thought to contribute to the functional limitations experienced by children with autism. Behaviors related to sensory processing difficulties can be detected prior to diagnosis. Retrospective videotape analysis suggests that infants later diagnosed with autism exhibit auditory under- and over-responsiveness and delayed response to name more often than typically developing children or children with developmental delays.  Several of these studies report that sensorimotor and social development features can be used to distinguish young children later diagnosed with autism from neurotypical and developmentally delayed children. Further, early identification and treatment of sensory processing deficits in young children with early signs of autism may promote more typical developmental patterns thereby reducing the severity of core autism symptoms.  Currently, identification of auditory processing disorders in young children is reliant on imprecise proxy-report measures. There is limited neurophysiologic research available regarding auditory processing of young children with early signs of autism.

Objectives:  

This paper will describe auditory processing function using Event Related Potentials while administering a novel phoneme discrimination task in young children with and without early signs of autism during the second year of life.

Methods:  

A total of 50 children (12-24 months of age) were recruited to this study. Children were divided into two groups based on their scores on the Autism Detection for Early Childhood (ADEC).  Inclusion criteria: children between 12-24 months of age who passed their newborn hearing screening. Exclusion criteria: children with developmental disability other than autism.  Auditory processing function was evaluated using an Event Related Potentials (ERP), mismatch negativity paradigm.  MMN is a pre-attentive measure of sensory processing elicited by speech sounds.  

Results:  

Preliminary data analysis displays trends in participants with and without early signs of autism in their auditory processing.  Scores on the ADEC indicate a significant difference (p<0.001) between the groups with and without early signs of autism. The group with no early signs of autism (n=21) scored (M=3.2, S.D. =1.3) compared to the early signs of autism group (n=19; M=8.6, S.D. =2.5).  Additionally, visual inspection of ERP waveforms indicate a higher amplitude to deviant stimuli in the group with no early signs of autism as compared to the group with early signs of autism indicating attenuated responsiveness to speech sounds in young children with early signs of autism. Final analysis will be completed by March, 2010 and will include data from 50 participants.

Conclusions:  

This study addresses a significant gap in scientific research specific to auditory processing in children with early signs of autism.  As hypothesized, children with early signs of autism exhibited attenuated responsiveness to speech sounds as evidenced by lower amplitude to deviant stimuli as compared to children with no early signs of autism.