PROJECT SUMMARY/ABSTRACT
Down syndrome (DS) is the leading genetic cause of intellectual disability. Although delayed, cognitive
skills develop across childhood and into early adulthood in DS. In adulthood, the study of cognitive functioning
in DS shifts from a focus on improvement to a focus on cognitive loss. Because of the triplication of genes located
on chromosome 21, individuals with DS are at risk for an earlier onset and increased incidence of Alzheimer’s
Disease (AD). In the general population, the diagnosis of AD is preceded by long preclinical and prodromal
phases that extend over two decades, and language markers are early indicators of the progression of AD. In
individuals with DS, however, gaps in our understanding of development across the lifespan present significant
hurdles for research on the progression from normative (albeit delayed) development to the early phases of later
cognitive decline. Crucial goals of DS research include elucidating variations in the patterns of development and
decline, identifying factors that may be protective and foster resilience against cognitive decline, and developing
interventions to support cognitive resilience. Developing measurement tools that that can be used to characterize
both growth and decline and evaluating their psychometric properties is vital for understanding disease
progression, recognizing potential points of intervention, and evaluating the efficacy of new treatments. In this
project, we propose, using a dataset previously collected from 107 participants with DS (6 – 23 years of age), to
(1) evaluate the psychometric properties of 9 aging-sensitive spoken language metrics and (2) characterize the
developmental trajectories of these metrics relative to participant characteristics to help determine the skills
contributing to development and decline. These aims will be addressed by re-transcribing and coding language
produced in two expressive language sampling contexts that are the first to be validated for use in DS. Measures
derived from the samples will include those indexing lexical and semantic skills, syntactic skills, and verbal
hesitations. Test-retest reliability will be assessed over a four-week interval. Standardized measures will be used
as indicators of construct validity. A two-year longitudinal follow-up will yield an estimate of relative sensitivity to
change of the various measures. The developmental trajectories of these metrics will be explored by describing
the performance as a function of participant characteristics (i.e., chronological age, nonverbal and verbal
cognition, working memory, adaptive skills, and autism symptomatology). By validating and establishing the
psychometrics of these aging-sensitive spoken language metrics in children, adolescents, and young adults with
DS, the proposed study will provide tools that can facilitate our understanding of development in DS and identify
potential treatment targets to promote resilience against later decline, bridging the conceptual gap between
studies of development and studies of decline.