Spelling Outcomes in Adolescents and Young Adults With Childhood Apraxia of Speech Reveal Persistent Linguistic Deficits

Purpose: The aim of this study was to characterize sources of variability in spelling performance in adolescents and young adults with a history of childhood apraxia of speech (CAS), including linguistic skills, motor–speech sequencing, spelling error types, and residual speech errors. We also examined whether selected endophenotypes differ from peers with a history of speech sound disorder without CAS (SSD-no CAS). Method: Correlations assessed relations among single-word decoding, oral language, phonological awareness, syllable sequencing, and spelling in participants with a history of CAS ( N = 32; ages 12;6–25;3 [years;months]). Linear regression, including an interaction term for the effect of group by endophenotype, was used to compare the spelling performance of participants with a history of CAS with age-matched peers with a history of SSD-no CAS ( N = 32; ages 12;1–25;1 [years;months]), using the same endophenotypes. Spelling errors were classified by linguistic type using the Spelling Sensitivity System (SSS), and persistent speech errors were examined in relation to spelling. Results: Within the CAS group, spelling was associated with decoding ( r = .88), phonological awareness ( r = .74), oral language ( r = .71), and syllable sequencing ( r = −.59). SSS analyses showed that implausible orthographic errors and phoneme omissions were significantly associated with spelling performance ( p = .005 and p = .046, respectively), whereas persistent speech errors were unrelated. A significant interaction between group and syllable sequencing ( p = .035) indicated that syllable sequencing predicted spelling only in the CAS group. Conclusions: Adolescents and young adults with histories of CAS rely on the same core linguistic skills for spelling as peers with a history of SSD-no CAS; however, spelling in CAS is additionally influenced by a motor–speech sequencing deficit, suggesting involvement of both linguistic and motor planning domains. Residual speech errors were unrelated to spelling, indicating that spelling difficulties arise from underlying representations rather than articulation. Supplemental Material: https://doi.org/10.23641/asha.32942729