Encoding, memory, and transcoding deficits in Childhood Apraxia of Speech

Abstract

A central question in Childhood Apraxia of Speech (CAS) is whether the core phenotype is limited to transcoding (planning/programming) deficits or if speakers with CAS also have deficits in auditory-perceptual encoding (representational) and/or memory (storage and retrieval of representations) processes. We addressed this and other questions using responses to the Syllable Repetition Task (SRT) [Shriberg, L. D., Lohmeier, H. L., Campbell, T. F., Dollaghan, C. A., Green, J. R., & Moore, C. A. (2009). A nonword repetition task for speakers with misarticulations: The syllable repetition task (SRT). Journal of Speech, Language, and Hearing Research, 52, 1189–1212]. The SRT was administered to 369 individuals in four groups: (a) typical speech–language (119), (b) speech delay–typical language (140), (c) speech delay–language impairment (70), and (d) idiopathic or neurogenetic CAS (40). CAS participants had significantly lower SRT competence, encoding, memory, and transcoding scores than controls. They were 8.3 times more likely than controls to have SRT transcoding scores below 80%. We conclude that speakers with CAS have speech processing deficits in encoding, memory, and transcoding. The SRT currently has moderate diagnostic accuracy to identify transcoding deficits, the signature feature of CAS.

Keywords:

• apraxia
• dyspraxia
• genetics
• motor speech disorder
• speech sound disorder

Acknowledgements

We thank the following colleagues and collaborators for their significant contributions to this study: Richard Boada, Thomas Campbell, Lisa Freebairn, Jordan Green, Heather Karlsson, Barbara Lewis, Jane McSweeny, Christopher Moore, Bruce Pennington, Heather Leavy Rusiewicz, Christie Tilkens, and David Wilson. Primary grant support was provided by the National Institute on Deafness and Other Communicative Disorders (NIDCD No. DC00496), by subcontracts with NIDCD No. DC00822, NIDCD No. DC00528, and NIMH No. 38820, a grant from the General Clinical Research Center at Children's Hospital of Pittsburgh (M01RR00084), and a core grant to the Waisman Center from the National Institute of Child Health and Development (HD03352).

Declaration of Interest: The authors report no declaration of interest. Primary grant support was provided by the National Institute on Deafness and Other Communicative Disorders (NIDCD No. DC00496), by subcontracts with NIDCD No. DC00822, NIDCD No. DC00528, and NIMH No. 38820, a grant from the General Clinical Research Center at Children's Hospital of Pittsburgh (M01RR00084), and a core grant to the Waisman Center from the National Institute of Child Health and Development (HD03352).