The acquisition of different classes of words in Spanish children with Down syndrome.

PURPOSE: The primary aim of this study was to analyze the acquisition of different classes of words in Spanish-speaking children with Down syndrome (DS), with special emphasis on nouns and verbs. A second objective was to compare the results obtained with those reported by Checa et al. (2016), who used a different measure to study vocabulary composition.

METHOD: We studied 108 children with DS and 108 children with typical development (TD), with mental ages between 9 and 29 months (DS M = 21;26 months;days, TD M = 20;23) and chronological ages between 8;24 and 68;19 months;days (mean = 41;11 and 20;19 for DS and TD, respectively). Children were matched individually for size of productive vocabulary and gender. Data were gathered using the MacArthur-Bates CDIs, adapted to the profile of children with DS (the CDI-Down). Relative proportions were used as the measure of vocabulary.

RESULTS: The results differed from those obtained by Checa et al. (2016) when using absolute proportions to examine vocabulary composition. The most significant difference was the trend among children with DS to produce fewer verbs and closed-class words (articles, prepositions, pronouns, conjunctions, and auxiliaries). There were no differences in the production of nouns and social words.

CONCLUSIONS: The tendency of children with DS to produce fewer verbs and closed-class words could be due to difficulties with morphology and syntax. This underlines the importance of morphosyntactic skills for learning these classes of words. The methodological and clinical implications of the results are discussed.