The relationship between speech, oromotor, language and cognitive abilities in children with Down's syndrome.

Abstract

Background: Children and young people with Down's syndrome (DS) present with deficits in expressive speech and language, accompanied by strengths in vocabulary comprehension compared to nonverbal mental age. Speech intelligibility is particularly impaired, but whether speech is delayed or disordered is a controversial topic. Most studies suggest a delay, but no studies explore the relationship between cognitive or language skills and intelligibility. This study sought to determine whether severity of speech disorder correlates with language and cognitive level and to describe the types of errors, developmental or non-developmental, that occur in the speech of children and adolescents with DS. Methods & Procedures: 15 children and adolescents with DS (aged 10 to 18) were recruited. Participants completed a battery of standardised speech, language and cognitive assessments. The phonology assessment was subject to process analyses. Results from each test were correlated to determine relationships. Outcome & Results: People with DS present with deficits in receptive and expressive language that is not wholly accounted for by their cognitive delay. Receptive vocabulary is a strength in comparison to language skills, but it was unclear whether it is more advanced compared to non-verbal cognitive skills. The majority of speech errors were developmental in nature but all of the children with DS showed at least one atypical or non-developmental speech error.Conclusions: Children with DS present with speech disorders characterised by (often unusual) atypical errors alongside many developmental errors. Lack of correlation between speech and cognition or language suggests that the speech disorder in Down's syndrome is not simply due to cognitive delay.