Although one in four children with autism remain minimally verbal past age five, we do not know all the factors that limit spoken language in these minimally verbal children with autism. One powerful contributor may be a concomitant motor speech disorder, Childhood Apraxia of Speech (CAS). CAS is an impairment in the ability to plan and sequence for speech, which renders speech inconsistent and imprecise. But because producing intelligible speech is a prerequisite to acquiring spoken language, there is an urgent need to understand how CAS may affect speech movements and intelligibility in minimally verbal children with autism, and to develop interventions that incorporate strategies to address CAS, when present. This project proposes three studies to investigate the relationship between CAS and speech in minimally verbal children with autism and CAS. First, we compare a group of 11 minimally verbal children with autism who meet criteria for CAS to a group of 11 who do not meet criteria for CAS. We hypothesize that facial movement tracking, a non-invasive method to investigate speech motor function, will reveal that the +CAS group show lower movement consistency and precision than the ?CAS group. Next, we investigate the relationship of clinical signs of CAS to speech movement parameters and to intelligibility. We hypothesize that more severe CAS predicts lower movement consistency and precision, and lower intelligibility, in an additional group of 22 minimally verbal children with autism+CAS. Finally, we use the previous investigations to inform treatment for a group of 20 minimally verbal children with autism+CAS. First we identify the speech movements for each child that are both disordered and degrade intelligibility,. Then, we create a set of mono- and bisyllabic stimuli involving these movements and train participants on a subset of them in a series of single-subject experiments. Treatment will involve principles of motor learning (massed and distributed practice) and dynamic cueing, which have been shown to be effective for treating CAS. Both perceptual (intelligibility-based) and objective (movement-based) outcome measures will demonstrate the extent to which this targeted treatment improves speech production in these children. The findings will inform clinical practice for minimally verbal children with autism and lead to the development of novel interventions for this severely affected population.
Comorbid Childhood Apraxia of Speech (CAS), a motor speech disorder affecting speech movement planning, may be one factor limiting the ability of some minimally verbal children with autism to acquire spoken language. This project aims to identify a cohort of minimally verbal children who meet criteria for autism and CAS and, using kinematic analysis of speech, to quantify how CAS affects speech movement consistency and precision. The relationship of speech movement parameters, intelligibility, and signs of CAS will be investigated in order to identify movements that are both disordered and intelligibility-reducing. These procedures will be used to create a set of mono- and bisyllabic stimuli, unique to each participant, that can reveal whether CAS-specific treatment, appropriately modified for minimally verbal children with autism, improves their speech.
