Predicting Expressive Language Change in Children With Autism Spectrum Disorder

Abstract

Children with autism spectrum disorder (ASD) show differences in their communication development when compared to children who are typically developing and other clinical populations. In addition, children with ASD show divergence and delays in their expressive language when compared to each other, and a reported 30% do not develop spoken language even with access to early intervention. In order to support children with ASD in their communication development, there is a critical need for (a) detailed accounts of the emergence of expressive language for children receiving early intervention, (b) investigation of factors that might explain differences in expressive language abilities, and (c) investigation of sensitive predictors of expressive language change for children receiving early intervention. Children with ASD are often recommended augmentative and alternative communication (AAC) as part of early intervention to augment existing communication abilities, thus providing a complementary communication system while supporting early language development. Augmentative and alternative communication can be introduced as a focused intervention to target communication specifically, or it can be introduced as part of a comprehensive intervention program targeting multiple domains of learning. When used as part of a comprehensive intervention program, AAC is believed to support communication development broadly, including children’s use of spoken language. Despite emerging evidence for its effectiveness as a focused intervention and potential to support spoken language development within the context of comprehensive interventions, little research exists examining the mechanisms underpinning outcomes of AAC interventions. The current project aimed to address this gap by investigating both the emergence of expressive language in children with ASD, and factors underpinning concurrent and longitudinal expressive language abilities for children receiving an AAC-infused comprehensive intervention program. This research was conducted as a series of three studies: Study 1 investigated the communication profiles of 246 children with ASD upon entry and exit to a comprehensive early intervention program; Study 2 investigated mechanisms underpinning concurrent expressive language abilities, and Study 3 investigated predictors of longitudinal expressive language abilities, in 48 children with ASD receiving an AAC-infused comprehensive intervention program. The findings from Study 1 documented that 58.7% of children who started early intervention as minimally verbal remained minimally verbal after approximately 12 months of intervention, while 41.3% went on to develop phrase speech (using two-word phrases), highlighting an as yet unmet clinical need, as well as research need to understand these differences. The findings from Study 2 challenged previously held beliefs regarding word learning abilities in children with ASD, and extended on previous research by investigating the relationship between symbolic word learning and expressive language level. By focusing on processes that might be relevant to children’s development within interventions incorporating AAC, the findings from Study 3 provided preliminary data on the characteristics of children who might experience the largest gains in spoken language within AAC-infused comprehensive interventions. This research demonstrated a novel approach to investigating variability in expressive language development in children with ASD. The findings from this research demonstrate potential to explain some of the variability through analysis of social-cognitive learning processes that might help predict change within intervention. Finally, the findings of this research have potential to inform how researchers and clinicians approach individual differences in all children who present with complex developmental profiles.