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

Abstract

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 some 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.

Using Developmental Trajectories to Understand Developmental Disorders

“…The use of trajectories in the study of developmental disorders has its origin in growth curve modeling (see, e.g., Chapman, Hesketh, & Kistler, 2002;Rice, 2004;Rice et al, 2005;Singer Harris et al, 1997;Thelen & Smith, 1994;van Geert, 1991) and in the wider consideration of the shape of change in development (Elman et al, 1996;Karmiloff-Smith, 1998). The use of simple correlations to explore relationships between different cognitive abilities in disorders may also be seen as falling within the trajectory approach (discussed later in this article).…”

Language learning in Down syndrome: The speech and language profile compared to adolescents with cognitive impairment of unknown origin

“…The rate of development of nonverbal visual short-term memory skills, in six years of longitudinal study, is slower than nonverbal pattern analysis skills and predicts the rate of syntax comprehension growth or loss in adolescence (Chapman, Hesketh & Kistler, 2002).…”

Adaptaciones metodológicas para el análisis del discurso de niños con discapacidad intelectual: narrando sin lenguaje

“…Además de las comparaciones de grupo, algunos estudios han explorado los predictores de las habilidades narrativas. Los mejores predictores de MLU en narrativas fueron la edad, la memoria auditiva y la memoria visual (Chapman, Hesketh y Kistler, 2002). Cabe destacar que las personas con síndrome de Down poseen mayor capacidad para procesar el color como estímulo visual y menor para procesar los números como pensamiento abstracto (Fernández y García, 2014).…”

“…La representación de la agencialidad es llevada a cabo mediante habilidades comunicativas con el apoyo visual del libro álbum, lo cual coincide con lo que indicaban los estudios respecto de sus habilidades relacionadas con la memoria visual (Chapman, Hesketh y Kistler, 2002) y el procesamiento del color como estímulo visual (Fernández y García, 2014).…”