Morphosyntax is one of the most impaired aspects of language development in children with Down syndrome. The present study aimed to assess the emergence of multiword utterances in this population. Sixteen Italian-speaking children with Down syndrome were followed from 36 to 48 months of age. Data derived from an analysis of their spontaneous productions showed that although the mean productivity of multiword utterances increased over the three time points (36, 42 and 48 months), different growth patterns of early syntactic development could be identified: (1) null or marginal development; (2) a gradual increase in multiword production over time; (3) an increase in the production of more complex multiword utterances and a decrease or inverted U-shaped profile in the production of simpler multiword productions; (4) an inverted U-shaped profile in multiword productions. In addition, children showed an improvement in their ability to express different semantic functions by word combinations. Significant relationships were found between early syntactic skills and both the child's vocabulary size and developmental age. A better knowledge of the acquisition pace and content of word combinations could allow more effective rehabilitative treatment during the first steps of children's syntactic development.
Keywords: Down syndrome; Word combinations; longitudinal study; multiword utterances; syntactic development.