Efficacy of speech therapy in children with language disorders: specific language impairment compared with language impairment in comorbidity with cognitive delay

Abstract 

Objective: this article discusses the effect of speech therapy on language comprehension, language production and non-verbal functioning in two groups of children with developmental language disorders. Design: retrospective study—a follow-up after a mean of 2 years. Materials and methods: verbal and non-verbal functioning before and after therapy were examined in 31 language-impaired children with normal hearing and good health. In 16 children the language functioning was substantial behind their non-verbal functioning. They were categorised as children with specific language impairment (SLI). In 15 children the language problem was in comorbidity with cognitive delay, and these were categorised as children with non-SLI. At the first examination the children were at the age of 1;5–5;4 years and at the second examination they were at the age of 3;4–6;11 years. The children were examined for language comprehension (Standardised Dutch version of the Reynell Developmental Comprehension Scale), spontaneous language production (Groningen Diagnostic Speech norms) and non-verbal functioning (Snijders-Oomen non-verbal intelligence scale for children between 2 and 7 years). Results: in both groups, a significant improvement was found in language functioning as well as in non-verbal functioning. Language comprehension and non-verbal IQ-scores in both groups improved by about the same amount. Language production made significantly more progress in the SLI group than in the non-SLI group. The improvements in the SLI group were mainly reached by speech therapy, whereas in the non-SLI group this was less the case. Conclusions: verbal and non-verbal development can improve in young children with developmental language delay. This underlines the idea that language and cognitive development are interacting and influencing each other in a positive way. Children with SLI seem to benefit more from speech therapy, whereas children with cognitive delay seem to benefit more from special education.

Keywords:  Language impairment, Speech therapy, Special education, Verbal development, Non-verbal development