Cognitive functions in Childhood Apraxia of Speech

Purpose: Childhood Apraxia of Speech (CAS) is diagnosed on the basis of specific speech characteristics, in the absence of problems in hearing, intelligence, and language comprehension. This does not preclude the possibility that children with this speech disorder might demonstrate additional problems. Method: Cognitive functions were investigated in three domains: complex sensory-motor and sequential memory functions, simple sensory-motor functions, and non-related control functions. Seventeen children with CAS were compared to 17 children with normal speech development at two occasions within 15 months. Results: The children with CAS showed overall lower scores but similar improvement at Occasion 2 compared to the typically developing controls, indicating an overall delay in the development of cognitive functions. However, a specific deviant development in sequential abilities was found as well, indicated by significantly lower scores at Occasion 2 as compared to (younger) control children at Occasion 1. Furthermore, the scores on the complex sensory-motor and sequential memory tasks were significantly correlated with the severity of the speech impairment. Conclusions: These results suggest that CAS involves a symptom complex that not only comprises errors of sequencing speech movements, but implicates comorbidity in nonverbal sequential functioning in most children with CAS.