Advancing spoken and written language development in children with childhood apraxia of speech
Thesis DisciplineSpeech and Language Therapy
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
Children with childhood apraxia of speech (CAS) are likely to experience severe and persistent spoken and written language disorder. There is a scarcity of intervention research, however, investigating techniques to improve the speech and literacy outcomes of this population. The series of 5 experiments reported in this thesis investigated phonological awareness and early reading development in children with CAS and trialled a new intervention designed to advance the spoken and written language development of those affected. In the first experiment (presented in Chapter 2), a comparison of 12 children with CAS, 12 children with inconsistent speech disorder (ISD), and 12 children with typical speech-language development (TD) revealed that children with CAS may be particularly susceptible to phonological awareness and reading deficits. There was no difference in the articulatory consistency and speech severity of the CAS and ISD groups, and no difference in the receptive vocabulary of the CAS, ISD, and TD groups. The children with CAS exhibited poorer phonological awareness scores than the comparison groups and had a greater percentage of participants performing below the expected range for their age on letter knowledge, real word decoding, and phonological awareness normative measures. The children with CAS and ISD performed inferiorly than the children with TD on a receptive phonological representation task. The results showed that the children with CAS had a representational component to their disorder that needed to be addressed in intervention. In the second experiment (presented in Chapter 3), a follow-up pilot study was conducted to examine the long-term effects of a previously conducted intensive integrated phonological awareness programme (7 hours of intervention over 3 weeks) on 2 children with CAS. The children aged 7;3 and 8;3 at follow-up assessment had previously responded positively to the intervention. Results showed that the children were able to maintain their high accuracy in targeted speech repeated measures over the follow-up period. One child was also able to maintain her high accuracy in phonological awareness repeated measures. The children performed superiorly on a standardised phonological awareness measure at follow-up than at pre-intervention. Non-word reading ability showed a sharp increase during the intervention period, while minimal gains were made in this measure over the follow-up period. The findings suggested that an integrated intervention was a potential therapeutic approach for children with CAS. In the third experiment (presented in Chapter 4), the effectiveness of an integrated phonological awareness programme was evaluated for the 12 children (identified in the first experiment) aged 4 to 7 years with CAS. A controlled multiple single-subject design with repeated measures was employed to analyse change in trained and untrained speech and phoneme segmentation targets. A comparative group design was used to evaluate the phonological awareness, reading, and spelling development of the children with CAS compared to their peers with TD over the intervention. The children participated in two 6- week intervention blocks (2-sessions per week) separated by a 6-week withdrawal block. Seven children with CAS made significant gains in their production of trained and untrained speech words with 7 of these children demonstrating transfer of skills to connected speech for at least one target. Ten children showed significant gains in phoneme awareness, and 8 of these children demonstrated transfer of skills to novel phoneme awareness tasks. As a group, the children with CAS demonstrated accelerated development over the intervention period in letter knowledge, phonological awareness, word decoding, and spelling ability compared to their peers with typical development. In the fourth experiment (presented in Chapter 5), the speech, phonological awareness, reading, and spelling skills of children with CAS and TD were re-evaluated 6- months following completion of the intervention programme. A measure of reading accuracy and reading comprehension in a text reading task was administered to the children with CAS. There was no difference in the performance of the children with CAS in post-intervention and follow-up assessments. The children with CAS and children with TD presented with similar relative change in phonological awareness, reading, and decoding measures over the follow-up period. The connected reading performance of children with CAS mirrored their phonological awareness and decoding skills. The findings demonstrated that children with CAS were able to maintain gains achieved during the intervention but may need further support to promote sustained development in written language. In the fifth experiment (presented in Chapter 6), the long-term effects of the integrated phonological awareness programme for identical twin boys who participated in the research intervention at pre-school were examined. The study examined Theo and Jamie's spoken language, phonological awareness, reading, and spelling development during their first year of schooling. The results pointed to the benefit of providing phonological awareness within a preventative framework for children with CAS. Theo and Jamie experienced continued growth in speech and phonological awareness skills. They exhibited age-appropriate reading and spelling development during their first year of formal literacy instruction. It was concluded from this series of experiments that children with CAS are particularly vulnerable to phonological awareness and early reading difficulty, and that an integrated phonological awareness intervention is an effective means of developing speech, phonological awareness, reading, and spelling skills in most children with CAS. The intervention appears to target processes underlying spoken and written language development in this population. The results are discussed within a phonological representation deficit hypothesis of CAS and clinical implications of the findings are highlighted.