Background: This study considers the role of early speech difficulties in literacy development, in the context of additional risk factors. Method: Children were identified with speech-sound disorder (SSD) at the age of 3½ years, on the basis of performance on the Diagnostic Evaluation of Articulation and Phonology. Their literacy skills were assessed at the start of formal reading instruction (age 5½), using measures of phoneme awareness, word-level reading, and spelling; and three years later (age 8), using measures of word-level reading, spelling and reading comprehension. Results: The presence of early SSD conferred a small but significant risk of poor phonemic skills at age 5½ and of poor word reading at age 8. Furthermore, within the group with SSD, the persistence of speech difficulties to the point of school-entry was associated with poorer literacy-related skills, and children with ‘disordered’ speech errors had poorer word reading skills than children whose speech errors indicated ‘delay’. In contrast, the initial severity of the SSD was not a significant predictor of reading development. Beyond the domain of speech, the presence of a co-occurring language impairment was strongly predictive of literacy skills and having a family-risk of dyslexia predicted additional variance in literacy at both time-points. Conclusion: Early SSD alone has only modest effects on literacy development but when additional risk factors are present these can have serious negative consequences, consistent with the view that multiple risks accumulate to predict reading disorders.
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- Speech sound disorder
- language impairment
- disordered speech errors
- family risk of dyslexia