Longitudinal relationships between language and verbal short-term memory skills in children with Down syndrome.

Children with Down syndrome are at risk for language difficulties, the nature of which is not well understood. This study compared the longitudinal predictors of language skills in children with Down syndrome with those in typically developing control children matched for initial level of nonverbal mental ability. An age cohort of children with Down syndrome (n=43) and 57 typically developing control children was assessed on measures of vocabulary, grammar, and verbal short-term memory three times at yearly intervals. Children with Down syndrome showed slower development on all measures than the typically developing controls. Longitudinal analyses showed moderate to high stability of language and verbal short-term memory skills. Our results confirm earlier evidence of pervasive language learning difficulties in this group and suggest that early language intervention should be given high priority.