Structure of Cognitive Functions in Monolingual Preschool Children With Typical Development and Children With Developmental Language Disorder

Purpose: Developmental language disorder (DLD) is defined by persistent difficulties with language, but a growing body of evidence suggests that it is also associated with domain general and nonverbal information-processing deficits. However, the interconnections between cognitive functions, both nonverbal and language related, are still unclear. With the aim of gaining more comprehensive insight into the cognitive deficits related to DLD, we investigated and compared the cognitive structure of children with DLD and typically developing (TD) children. Method: As a part of the Helsinki longitudinal SLI study, monolingual Finnish preschoolers (N = 154; TD group: n = 66, DLD group: n = 88) were assessed with 23 tasks measuring nonverbal and verbal reasoning, language processing, memory, visuomotor functions, attention, and social cognition. Exploratory factor analysis and structural equation modeling were performed to examine latent constructs and to test measurement invariance between the TD and DLD groups. Results: Measurement invariance was not found across the TD and DLD groups. Best fitting structure for TD children included factors reflecting verbal abilities, processing speed/short-term memory, visuomotor functions, and visuoconstructive abilities/nonverbal reasoning. The DLD group's structure comprised nonverbal abilities, naming/expressive language, verbal comprehension, and verbal/declarative memory. Conclusions: The findings suggest that the structure of cognitive functions differs in TD children and children with DLD already at preschool age. Nonverbal functions seem more unified, whereas verbal functions seem more varying in preschoolers with DLD compared to TD children. The results can be used in future research for prognosis of DLD and planning interventions.