Motor-based Intervention for Childhood Apraxia of Speech: DTTC-Connect

The long-term goal of this research is to provide evidence-based treatment guidelines to enhance speech intelligibility and therefore, communicative participation, for children with childhood apraxia of speech (CAS). The overall objectives are to test the efficacy of Dynamic Temporal and Tactile Cueing-Connect (DTTC-Connect) and document changes in speech motor control at the connected speech level, when intervention is provided two times per week for eight weeks. The central hypothesis is that DTTC-Connect will lead to lasting improvements in phrase accuracy, speech intelligibility, and speech motor control, ultimately enhancing a child's communicative participation, as supported by our previous Dynamic Temporal and Tactile Cueing (DTTC) research and pilot data on DTTC-Connect. The following aims are examined: Aim 1: Quantify the effects of DTTC-Connect on connected speech accuracy and whether previous DTTC modifies response to DTTC-Connect. 68 children with CAS will receive 8 weeks of DTTC-Connect, with a subset of children returning from the prior DTTC randomized controlled trial (RCT). The working hypothesis is that untreated phrase accuracy (primary outcome) and speech intelligibility (secondary outcome) will increase pre-post DTTC-Connect with gains maintained at 8 weeks post-treatment in all children. It is hypothesized that prior DTTC RCT performance (returning participants) will predict untreated phrase accuracy pre-post DTTC-Connect. Linear mixed-effects models will be used to estimate the DTTC-Connect treatment effect and the moderation effect of prior DTTC exposure. Aim 2: Quantify the effects of DTTC-Connect on speech motor variability and whether previous DTTC modifies response to DTTC-Connect. Acoustic and kinematic (lip/jaw movement) data will be obtained pre- and post- DTTC-Connect from 68 children with CAS, including a subset of children returning from the prior DTTC RCT. The working hypothesis is that variability (secondary outcome) will be reduced in all children following DTTC-Connect, with changes maintained at 8 weeks post-treatment. Inclusion of returning children will allow the examination of extended treatment on speech motor control. It is hypothesized that the change in variability in the prior DTTC RCT will moderate the treatment effect with DTTC-Connect. Linear mixed-effects models will be used to estimate changes in variability over time as in Aim 1. Aim 3: Evaluate the effect of DTTC-Connect on communicative participation in children with CAS. Communicative participation (secondary outcome) will be assessed in all children pre- and post- DTTC-Connect. The working hypothesis is that children with CAS who receive DTTC-Connect will show meaningful gains in their attitudes about speaking and in caregiver-reported functional communication. Linear mixed-effects models will be used to estimate changes in communicative participation following DTTC-Connect. Upon completion of these aims, the expected outcome is to establish the efficacy of DTTC-Connect in a large cohort of children with CAS, while uncovering how previous response to word-level DTTC informs individualized treatment planning. In doing so, it will generate actionable insights to enhance clinical outcomes while also deepening theoretical understanding of speech motor learning in CAS.