Morphosyntactic development in German-speaking individuals with Down syndrome-longitudinal data

Area of Science:

• Linguistics
• Developmental Psychology
• Genetics

Background:

• Down syndrome is associated with language impairments, particularly in grammar.
• Longitudinal studies are crucial for understanding developmental trajectories in this population.
• The interplay between cognitive abilities and morphosyntactic development requires further investigation.

Purpose of the Study:

• To longitudinally track receptive and expressive grammar development in German-speaking individuals with Down syndrome.
• To investigate the role of nonverbal cognitive abilities and verbal short-term memory in morphosyntactic development.
• To identify potential triggers for expressive grammar advancement.

Main Methods:

• Longitudinal assessment of 17 German-speaking individuals with Down syndrome (aged 4;6-17;1 at T1).
• Two to three assessments over 4.5-8.5 years, using standardized measures for receptive grammar, nonverbal cognition, and verbal short-term memory.
• Elicitation tasks to evaluate expressive grammar, specifically subject-verb agreement and wh-question production.

Main Results:

• Significant improvement in receptive grammar from T1 to T2, but progress slowed with age, diminishing after 10 years.
• Expressive grammar gains were limited to participants mastering verbal agreement by age 10; those who didn't showed no progress in wh-question production.
• Nonverbal cognition and verbal short-term memory did not correlate with changes in receptive or expressive grammar.

Conclusions:

• Receptive grammar acquisition slows before adolescence in individuals with Down syndrome.
• Subject-verb agreement mastery may act as a trigger for further expressive grammatical development.
• Nonverbal cognitive abilities and verbal short-term memory do not appear to drive grammatical development in this population, informing clinical language therapy approaches.