Cognitive Development and Down Syndrome: Age-Related Change

from aaiddjournals.org:

Cognitive Development and Down Syndrome: Age-Related Change on the Stanford-Binet Test (Fourth Edition)

A study in the May issue of the American Journal on Intellectual and Developmental Disabilities by researchers affiliated with the University of Queensland (Australia) examined Stanford-Binet test performance by a large group of individuals with Down syndrome.  Authors report that the performance of the study sample on Stanford-Binet subtests measuring crystallized abilities (the ability to use skills, knowledge, and experience)  tended to plateau early in adulthood, whereas the test of fluid ability (the capacity to think logically and solve problems in novel situations, independent of acquired knowledge) continued to increase beyond the age of 30.  Authors note that the trend they observed is in opposition to the general population in which fluid abilities typically peak in early adulthood while crystallized abilities continue to increase. (full text available at no cost with member subscription to AJIDD)

Growth models for subtests of the Stanford-Binet Intelligence Scale, 4th edition (R. L. Thorndike, E. P. Hagen, & J. M. Sattler, 1986a, 1986b) were developed for individuals with Down syndrome. Models were based on the assessments of 208 individuals who participated in longitudinal and cross-sectional research between 1987 and 2004. Variation in performance among individuals was large and significant across all subtests except Memory for Sentences. Scores on the Memory for Sentences subtest remained low between ages 4 to 30 years. Greatest variation was found on the Pattern Analysis subtest, where scores continued to rise into adulthood. Turning points for scores on the Vocabulary and Comprehension subtests appeared premature relative to normative patterns of development. The authors discuss development at the subdomain level and analyze both individual and group trajectories.