The association of cognitive abilities with language disorder in 8-year-old children: A population-based clinical sample

Abstract

Background

Despite accumulated evidence that language development depends on basic cognitive processes, the balance in contributions of verbal and non-verbal cognitive skills to language abilities is still underexplored. Little is known about which cognitive measures best predict the degree of severity in children with language disorder (LD). Aims

To examine the association between verbal and non-verbal cognitive abilities with language abilities in typically developing and language impaired 8-year-old children, as well as which cognitive abilities are most effective in distinguishing LD severity levels. Methods & Procedures

Children (N = 509) from the Language-8 Study, which oversampled probable cases of children with LD from a population-based cohort in Norway, were assessed at 8 years. Language skills were assessed using the Norwegian Clinical Evaluation of Language Fundamentals—4 (CELF-4). Children's verbal and non-verbal cognitive abilities were assessed via standardized cognitive measures. An exploratory factor analysis (EFA) was first conducted to uncover the underlying factor structure of the cognitive variables. Using a hierarchical multiple regression analysis, we then examined to what extent the non-verbal cognition factor explained language abilities above and beyond verbal cognition factors. Lastly, multinomial logistic regression was used to examine which cognitive measures best predicted the degree of severity in the children with LD. Outcomes & Results

The EFA resulted in three factors (Verbal Cognition, Processing Speed and Memory, and Non-Verbal Cognition). The hierarchical multiple regression analysis revealed that all three cognitive factors contributed significantly to individual variation in language abilities. Non-Verbal Cognition explained 5.4% variance in language abilities above and beyond that accounted for by Verbal Cognition and Processing Speed and Memory. Results from the multinomial logistic regression analysis indicated that cognitive subtests, including Familiar Sequences, WASI Vocabulary and WASI Similarities, not only distinguished LD from typically developing children, but were also efficient in distinguishing severity of LD symptoms. Conclusions & Implications

This study confirms concurrent links between language and non-verbal cognitive skills above and beyond the contribution of verbal cognitive skills. The results provide further evidence that children with LD experience both language and cognitive problems in mid-childhood. Our findings suggest implications for LD intervention and diagnosis. The findings support the importance of measuring both verbal and non-verbal cognitive skills when making an LD diagnosis, and point to the potential of targeting underlying cognitive skills as one strategy to support language abilities.