Relationships between executive functions and vocabulary knowledge in Spanish-speaking children with and without developmental language disorder

Developmental language disorder (DLD) is often associated with deficits in executive functions (EFs). One common area of language difficulty in DLD is the development of vocabulary knowledge and it has been suggested that EF abilities may be linked to this difficulty. However, an explanation for this relationship remains unclear. The rationale for the current study examined the relationship between EFs and two aspects of vocabulary knowledge, receptive vocabulary size and vocabulary depth, in Spanish-speaking children with and without DLD. Vocabulary skills, the EFs of interference control, response inhibition, verbal and nonverbal working memory, and switching, were assessed in a total of 204 children aged 6-8 years: 105 with DLD and 99 with typical development (TD). Relationships were assessed using multiple regression models and path analysis, including EF as predictors, receptive vocabulary size and vocabulary depth as outcome or mediating variables, and age and non-verbal intelligence as covariates. In children with DLD, the EFs verbal working memory and switching were directly associated with receptive vocabulary size and indirectly with vocabulary depth. This indirect relationship was mediated by receptive vocabulary size. In contrast, no EFs were associated with receptive vocabulary size, and vocabulary depth in the TD group. These results suggest that verbal working memory and cognitive flexibility play a role in the cognitive mechanisms linked to vocabulary development in school children with DLD. Intervention programs aimed at improving vocabulary in this population should include EF activities.