Examining the relationship between oral language skills and executive functions : evidence from Greek-speaking 4–5-year-old children with and without developmental language disorder

Background: Children with Developmental Language Disorder (DLD) have been found to demonstrate low performance in Executive Functions (EFs). However, the evidence-based data is so far scarce, especially for 4–5-year-old children. Most of the existing research involved English - speaking populations, while very few studies have been carried out with non-English-speaking populations. Nevertheless, it is documented that possible differences in the language-cognition relations may exist due to the specific characteristics of each language, and studies across different languages could contribute to the above. Aims: The present study aimed to systematically investigate the profile of oral language and EF skills (verbal and non-verbal) and the way these skills are related with each other in 4–5-year-old Greek-speaking children with and without DLD Methods and procedures: Fifty-three children 4-5-year-old (age range: 51– 57 months)with DLD, and 62 typically developing (TD) peers (age range: 51– 57 months) were assessed on a standardized psychometric battery for oral language skills (phonological and morphological awareness, oral language comprehension, vocabulary knowledge, narrative speech and pragmatics) and on a series of verbal(v) and nonverbal (nv) tasks tapping EFs skills (updating-accuracy, inhibition –(accuracy and reaction time)-, and cognitive flexibility). Outcomes and results: Children with DLD demonstrated statistically significant lower performance across all oral language measures in comparison to their TD peers. Additionally, they performed significantly lower in the updating (nv) task, as well as in cognitive flexibility (v & nv) in comparison to the TD group. Further regression analyses demonstrated that updating (nv), inhibition (nv) and cognitive flexibility (v) predicted oral language comprehension in children with DLD while updating (v & nv), inhibition-reaction time (nv) and cognitive flexibility (v & nv) predicted phonological and morphological awareness, oral language comprehension, narrative speech as well as total language score in TD children. Conclusions and implications: These results provide important information on the profile of oral language and EF skills in children with DLD compared to their TD peers as well as on the relationship of these skills in both groups. The findings also suggest that improving EFs skills may be a possible way for improving oral language skills in young children with DLD. Our findings are discussed in terms of their theoretical as well as practical implications in terms of diagnostic and intervention procedures for children with DLD