Examining Potential Mediators of the Relationship Between Developmental Language Disorder and Executive Function Performance in Preschoolers.

Purpose: The goal of this study was to examine potential mediators of the relationship between developmental language disorder (DLD) status and executive function performance.

Method: Participants included preschoolers, of whom 80 met the diagnostic criteria for DLD and 103 were categorized as having typical language abilities. Participants' nonverbal IQ and receptive vocabulary were assessed via standardized tests, and their executive function was tested using the Dimensional Change Card Sort. Maternal education was collected via caregiver report and served as a measure of socioeconomic status (SES).

Results: Group comparisons confirmed that participants with DLD had lower language scores, nonverbal IQ scores, executive function scores, and SES relative to peers with typical language. Additionally, these variables were significantly positively correlated. Multiple mediation analyses indicated that both nonverbal IQ and receptive vocabulary were significant partial mediators of the effect of DLD status on executive function scores. However, a direct effect of DLD status on executive function remained significant in a model that included the mediators and covaried maternal education.

Conclusions: Group differences in nonverbal IQ and receptive vocabulary can partially explain why children with DLD tend to have lower executive function scores relative to peers with typical language. However, even after accounting for these mediators, there is a significant, large direct effect of DLD status on executive function performance, which suggests that the groups' difference in executive functioning is not fully explained by other variables.