Working memory in school-age children with and without a persistent speech sound disorder

Purpose: The aim of this study was to explore the role of working memory processes as a possible cognitive underpinning of persistent speech sound disorders (SSD). Method: Forty school-aged children were enrolled; 20 children with persistent SSD (P-SSD) and 20 typically developing children. Children participated in three working memory tasks - one to target each of the components in Baddeley's working memory model: phonological loop, visual spatial sketchpad and central executive. Result: Children with P-SSD performed poorly only on the phonological loop tasks compared to their typically developing age-matched peers. However, mediation analyses revealed that the relation between working memory and a P-SSD was reliant upon nonverbal intelligence. Conclusion: These results suggest that co-morbid low-average nonverbal intelligence are linked to poor working memory in children with P-SSD. Theoretical and clinical implications are discussed.