Predicting Longitudinal Change in Language Production and Comprehension in Individuals With Down Syndrome

Hierarchical Linear Modeling

chapman{at}waisman.wisc.edu

Longitudinal change in syntax comprehension and production skill, measured four times across a 6-year period, was modeled in 31 individuals with Down syndrome who were between the ages of 5 and 20 years at the start of the study. Hierarchical Linear Modeling was used to fit individual linear growth curves to the measures of syntax comprehension (TACL-R) and mean length of spontaneous utterances obtained in 12-min narrative tasks (MLU-S), yielding two parameters for each participant's comprehension and production: performance at study start and growth trajectory. Predictor variables were obtained by fitting linear growth curves to each individual's concurrent measures of nonverbal visual cognition (Pattern Analysis subtest of the Stanford-Binet), visual short-term memory (Bead Memory subtest), and auditory short-term memory (digit span), yielding two individual predictor parameters for each measure: performance at study start and growth trajectory. Chronological age at study start (grand-mean centered), sex, and hearing status were also taken as predictors. The best-fitting HLM model of the comprehension parameters uses age at study start, visual short-term memory, and auditory short-term memory as predictors of initial status and age at study start as a predictor of growth trajectory. The model accounted for 90% of the variance in intercept parameters, 79% of the variance in slope parameters, and 24% of the variance at level 1. The same predictors were significant predictors of initial status in the best model for production, with no measures predicting slope. The model accounted for 81% of the intercept variance and 43% of the level 1 variance. When comprehension parameters are added to the predictor set, the best model, accounting for 94% of the intercept and 22% of the slope variance, uses only comprehension at study start as a predictor of initial status and comprehension slope as a predictor of production slope. These results reflect the fact that expressive language acquisition continues in adolescence and is predicted by syntax comprehension and its growth trajectory.

KEY WORDS: Down syndrome, language development, comprehension, production, short-term memory

Submitted on September 25, 2001
Accepted on April 9, 2002

This article has been cited by other articles:

				J. A. Ford and L. M. Milosky Inference Generation During Discourse and Its Relation to Social Competence: An Online Investigation of Abilities of Children With and Without Language Impairment J Speech Lang Hear Res, April 1, 2008; 51(2): 367 - 380. [Abstract] [Full Text] [PDF]

				A. S. McDuffie, H. A. Sindberg, L. J. Hesketh, and R. S. Chapman Use of Speaker Intent and Grammatical Cues in Fast-Mapping by Adolescents With Down Syndrome J Speech Lang Hear Res, December 1, 2007; 50(6): 1546 - 1561. [Abstract] [Full Text] [PDF]

				T. F. Campbell, C. Dollaghan, J. E. Janosky, and P. D. Adelson A Performance Curve for Assessing Change in Percentage of Consonants Correct Revised (PCC-R) J Speech Lang Hear Res, August 1, 2007; 50(4): 1110 - 1119. [Abstract] [Full Text] [PDF]

				C. Valiquette, A.-M. Gerin-Lajoie, and A. Sutton A visual graphic tool to support the production of simple sentence structures in a student with learning disability Child Language Teaching and Therapy, June 1, 2006; 22(2): 219 - 240. [Abstract] [PDF]

				R. S. Chapman, H. Sindberg, C. Bridge, K. Gigstead, and L. Hesketh Effect of memory support and elicited production on fast mapping of new words by adolescents with down syndrome. J Speech Lang Hear Res, February 1, 2006; 49(1): 3 - 15. [Abstract] [Full Text] [PDF]

				L. E. Hewitt, A. S. Hinkle, and A. W. Miccio Intervention to Improve Expressive Grammar for Adults With Down Syndrome Communication Disorders Quarterly, January 1, 2005; 26(3): 144 - 155. [Abstract] [PDF]