The Interplay of Morphosyntax and Verbal and Nonverbal Short-Term Memory in Children and Adolescents with Down Syndrome

This study explores language difficulties, particularly in morphosyntax, as well as challenges in short-term memory (STM) and the interaction between these aspects in children and adolescents with Down syndrome (DS). Previous studies underscore difficulties in syntax and morphology among individuals with DS, as well as difficulties in both verbal and visual STM. However, the link between memory deficits and language impairment remains inconclusive. Involving 22 participants, including 12 with DS, our study assessed sentence comprehension, sentence production, morphological production, phonological STM, and visual and auditory digit span tasks. Results reveal significant challenges in syntax and morphology for individuals with DS in receptive and expressive domains, as well as in visual and verbal STM skills, compared to mental age-matched peers. Contrary to expectations, no distinction is observed between receptive and expressive syntax. Additionally, disparities emerge in DS individuals' performances in noun versus verb morphology, with significant differences from controls. Verbal STM impairment is noted, predicting sentence comprehension and morphological production, while visual STM does not show a significant predictive relationship. At the individual level, a nuanced picture deviates from group comparisons. Although most individuals face challenges in syntax and nonverbal and verbal STM skills, variations occur in morphological measures.