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

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. WHAT THIS PAPER ADDS: What is already known on the subject Language development is dependent on basic cognitive processes. These include both verbal and non-verbal cognitive abilities. Children with LD often experience both language and cognitive problems. There is evidence that performance on cognitive tests may be associated with the degree of severity of LD. What this paper adds to existing knowledge The current results from a large population-based cohort establish that a number of verbal and non-verbal cognitive abilities are tightly linked to variation in language abilities and the degree of severity of LD. Our study confirms concurrent links between language and non-verbal cognitive abilities above and beyond the contribution of verbal cognitive abilities. We also identify specific verbal and non-verbal cognitive tests that distinguish between typical children and children with LD, as well as LD severity. What are the potential or actual clinical implications of this work? Our findings support the importance of measuring both verbal and non-verbal cognitive skills when making an LD diagnosis. Our findings also point to the potential of targeting underlying cognitive skills as one strategy to support language abilities. We suggest that future intervention studies focus on the impact of non-verbal cognitive skills on language development in children with LD.

Preschool Speech Intelligibility and 8-Year Literacy: A Moderated Mediation Analysis.

Purpose The aims of this study were (a) to examine the relationship between speech intelligibility at the age of 5 years and literacy skills at the age of 8 years, (b) to explore the possible mediating or moderating role of broader language skills at 5 years in the relationship of interest, and (c) to assess whether the potential risk factors (child gender; maternal education levels; and family history of speech, language, reading, and writing difficulties) influence the relationship between speech intelligibility and literacy in terms of moderated mediation effects. Method We used mother-reported questionnaire data on 16,184 children participating in the population-based, prospective Norwegian Mother, Father and Child Cohort Study as well as conducted linear regression analyses using the PROCESS macro in SPSS. In addition, logistic regression was conducted to make predictions about risk. Results The association between speech intelligibility at 5 years and literacy skills at 8 years was statistically significant (ß = .168, p < .001). Children with speech problems at 5 years had a risk ratio of 2.38 (95% CI [2.10, 2.70]) and an odds ratio of 2.74 (95% CI [2.35, 3.19]), as compared to children without such problems. Broader language skills at 5 years partially mediated the relationship between speech intelligibility at 5 years and literacy at 8 years, and the effect of language skills appeared to be moderated by child gender, a family history of language difficulties, a family history of reading difficulties, and maternal education. Conclusions Severity of speech problems indexed by parent-reported speech intelligibility in preschool predicted school-age literacy problems. Broader language skills are a crucial mediating mechanism through which these problems are linked, and the mediated relationship is amplified by female gender, low maternal education, family history of language difficulties, and family history of reading difficulties. The findings call for increased use of a multiple-risk model when planning early interventions in children with unclear speech.

Predicting Literacy Skills at 8 Years From Preschool Language Trajectories: A Population-Based Cohort Study.

Purpose This article explored the predictive values of three main language delay (LD) trajectories (i.e., persistent, late onset, and transient) across 3-5 years on poor literacy at 8 years. Additionally, the effect of gender was assessed, using both gender-neutral and gender-specific thresholds. Method The data comprised mother-reported questionnaire data for 8,371 children in the Norwegian Mother, Father, and Child Cohort Study. Analyses were conducted using binary logistic regression in SPSS to make predictions about risk. Results LD reported at preschool age was associated with excess risk of poor literacy at 8 years with odds ratios ranging from 3.19 to 9.75 dependent on trajectory, persistent LD being the strongest predictor. The odds ratio of transient LD was similar to that of late-onset LD. Gender was not found to play an important role in the association between oral language and literacy, as the gender difference disappeared when gender-specific deficit criterion was used. Conclusion Our study supports the longitudinal association between preschool oral language and school-aged literacy skills and highlights the importance of different LD trajectories across preschool ages in predicting later literacy. Furthermore, practitioners are recommended to consider gender-specific cutoffs in relation to language and literacy measures.