Vocabulary and expressive morpho-syntax in individuals with Down syndrome: Links to narration.

Background: Narrative ability is crucial for social participation in everyday and school life but involves different language abilities such as vocabulary and morpho-syntax. This is particularly difficult for individuals who display both language and cognitive impairments. Previous research has identified productive vocabulary as a possible key factor for narrative performance in individuals with Down syndrome. Considering a close connection between lexical and morpho-syntactic performance within language acquisition and the distinct impairments that individuals with Down syndrome display concerning their morpho-syntactic skills, the nature of a relation between vocabulary and narrative skills under the influence of grammatical deficits requires further investigation.

Methods: Narrations were obtained from 28 children and adolescents with Down syndrome (aged 10;0-20;1) using a non-verbal picture book. Narrative abilities were rated using the Narrative Scoring Scheme across seven narrative aspects (including macro- and microstructure). Vocabulary analyses and morpho-lexical context analyses including verb and conjunction enumerations, evaluation of verb position and MLU were conducted. Findings from the transcript analysis have been supplemented with data from standardized language measures evaluating expressive lexical and morpho-syntactic development. A multiple regression analysis was conducted to identify significant predictors for narrative outcome in the participants with Down syndrome.

Results: Lexical analyses revealed a high heterogeneity in production of subordinating conjunctions as a link between lexical and morpho-syntactic abilities. Comparisons of standardized and narrative data demonstrated differences in subordinate clause production depending on the elicitation setting. A multiple regression analysis identified the number of different verbs in the narrative task as the most significant predictor for narrative performance in individuals with Down syndrome.

Discussion And Implications: The findings of this study contribute to the knowledge regarding factors that influence narrative performance in individuals with language impairment. A differentiated verb lexicon can be identified as the key ability for reaching advanced narrative skills in participants with Down syndrome. These findings are of clinical relevance for therapeutic and educational support and contribute to an understanding of the relation between strengths in vocabulary and morpho-syntactic weaknesses in individuals with Down syndrome within communicative participation.