Language skills of children and adolescents with Down syndrome: I. Comprehension.

This study investigates the development of vocabulary and syntax comprehension skills cross-sectionally in 48 children and adolescents with Down syndrome (Trisomy 21), aged 5-20 years, in comparison to 48 control children aged 2-6 years matched statistically for nonverbal mental age and mother's years of education. Age-equivalent scores on vocabulary (PPVT-R) and syntax (TACL-R) comprehension tests differed in the Down syndrome group but not the control group; vocabulary comprehension was relatively more advanced than syntax. Age-equivalent scores on nonverbal cognitive subtests of pattern analysis and short-term memory for bead arrangements (Stanford-Binet, 4th ed.) also differed for the Down syndrome group but not the control group, indicating an unusual pattern of nonverbal cognitive function in the Down syndrome group. Stepwise multiple regression analyses showed that chronological age and mean mental age, collectively, accounted for 78% of the variability in vocabulary comprehension and 80% of the variability in syntax comprehension in the Down syndrome group, with total passes on a hearing screening accounting for an additional 4% in each case. Implications for research are discussed.