The Hypothesis of Apraxia of Speech in Children with Autism Spectrum Disorder

Abstract

In a sample of 46 children aged 4 to 7 years with Autism Spectrum Disorder (ASD) and intelligible speech, there was no statistical support for the hypothesis of concomitant Childhood Apraxia of Speech (CAS). Perceptual and acoustic measures of participants' speech, prosody, and voice were compared with data from 40 typically-developing children, 13 preschool children with Speech Delay, and 15 participants aged 5 to 49 years with CAS in neurogenetic disorders. Speech Delay and Speech Errors, respectively, were modestly and substantially more prevalent in participants with ASD than reported population estimates. Double dissociations in speech, prosody, and voice impairments in ASD were interpreted as consistent with a speech attunement framework, rather than with the motor speech impairments that define CAS. Key Words: apraxia, dyspraxia, motor speech disorder, speech sound disorder A continuing question about persons with Autism Spectrum Disorder (ASD) is whether reported diminished abilities in gross, fine, and oral motor control are causally associated with reported deficits in speech acquisition and performance. The classification term for the speech deficit in question, recently adapted by the American Speech-Language-Hearing Association (ASHA;2007a, 2007b, is Childhood Apraxia of Speech (CAS). Medical literatures and speech literatures in other countries continue to prefer several other classificatory terms for this disorder, including dyspraxia and developmental verbal dyspraxia. "Childhood" apraxia of speech differentiates congenital and early acquired forms of apraxia of speech from adult acquired forms, but creates a nosological problem because childhood apraxia of speech generally persists into adulthood. We will use the ASHA (2007a) recommended term-CAS.The strong form of the hypothesis in the title of this paper, hereafter, the 'CAS-ASD' hypothesis, is that CAS is a sufficient cause of lack of speech development in at least some children classified as nonverbal ASD. The weak form of the CAS-ASD hypothesis is that CAS contributes to the inappropriate speech, prosody, and/or voice features reported in some children and adults with verbal ASD. Although the present report addresses only the weak form of the hypotheses, the conceptual framework and implications for treatment NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript apply to both forms of the hypothesis. Forthcoming research addresses the strong form of the hypothesis. The following sections provide (a) rationales for the CAS-ASD hypothesis, (b) an overview of idiopathic speech sound disorders, and (c) a summary of speech, prosody, and voice findings in verbal ASD. Rationales for the CAS-ASD HypothesisThe American Speech-Language-Hearing Association Position Statement recommends the following definition of CAS:Childhood apraxia of speech (CAS) is a neurological childhood (pediatric) speech sound disorder in which the precision and consistency of movements underlying speech are impaired in the absence of neuromuscula...

Childhood Apraxia of Speech (CAS) in two patients with 16p11.2 microdeletion syndrome

“…7 A recent study tested the hypothesis that comorbid CAS in autism explains, at least in part, the unusual speech, prosody, and voice behaviors reported in children with verbal autism. 24 Findings from a study of 46 patients with verbal autism whose genetic backgrounds were not assessed, did not support the hypothesis, with continuing studies focusing on the potential causal role of CAS in nonverbal autism. Clearly, such studies should include speech, prosody, and voice profiling of children with 16p11.2 microdeletions disrupting SEZ6L2 and DOC2A and possibly other deleted genes in the 16p11.2 deletion syndrome.…”

“…Readers unfamiliar with CAS can find additional information in a technically accessible tutorial on the types of motor speech disorders in idiopathic and complex neurodevelopmental contexts, including CAS. 24 Table 2 is a summary of the assessment findings for P1 and P2 that follow, including information in six domains associated with the CAS phenotype.…”

Using Spoken Language Benchmarks to Characterize the Expressive Language Skills of Young Children With Autism Spectrum Disorders

“…It is possible that the significant impairments in phonological and expressive language observed in this subset of children may be due to oral-motor difficulties. The hypothesis that apraxia of speech underlies the phonological delays observed in children with ASD has not been supported (Shriberg, Paul, Black, & van Santen, 2011). There is, however, evidence of fine and gross motor skills delays in young children with ASD (Bhat, Galloway, & Landa, 2012;Lloyd, MacDonald, & Lord, 2013).…”

12p13.33 microdeletion including ELKS/ERC1, a new locus associated with childhood apraxia of speech

“…3 CAS have been described occasionally with genetic disorders such as galactosemia, type 1 neurofibromatosis or in chromosomal rearrangements, in particular encompassing the FOXP1 or FOXP2 genes. [40][41][42][43] Four genes have been reported in association with speech disorders, often associated with other neurobehavioural abnormalities. These include mutations in the CNTNAP2, FOXP1 FOXP2 and SRPX2 genes.…”