What do diagnostic test data tell us about differences in the profiles of children diagnosed with reading disability or language impairments?

A systematic review of factors that impact reading comprehension in children with developmental language disorders

Children with developmental language disorder (DLD) have a high rate of co-occurring reading difficulties. The current study aims to (i) examine which factors within the Active View of Reading (AVR; Duke & Cartwright, 2021) apply to individuals with DLD and (ii) investigate other possible factors that relate to reading comprehension ability in individuals with DLD, outside the components in the AVR. Electronic database search and journal hand-search yielded 5058 studies published before March 2022 related to reading comprehension in children with DLD. 4802 articles were excluded during abstract screening, yielding 256 studies eligible for full-text review. Following full-text review, 44 studies were included and further coded for demographics, language of assessment, description of reported disabilities, behavioral assessment, and reading comprehension assessment. While the results aligned with the AVR model, three additional factors were identified as significantly relating to reading comprehension abilities in children with DLD: expressive language (oral and written), question types of reading assessment, and language disorder history. Specifically, expressive language was positively associated with reading comprehension ability, while resolved DLD showed higher reading comprehension abilities than persistent DLD. Furthermore, children with DLD may face additional difficulties in comprehending inference-based questions. This study provides factors for researchers, educators, and clinical professionals to consider when evaluating the reading comprehension of individuals with DLD. Future research should further explore the relative importance of factors of the AVR to reading comprehension outcomes throughout development.

The relationship between developmental language disorder and dyslexia in European Portuguese school-aged children

Developmental Language Disorder (DLD) [Also referred to as Specific Language Impairment (SLI)] and dyslexia are neurodevelopmental disorders which show similar behavioral manifestations. In this study, between-group comparisons and frequency analysis were combined to investigate the relationship between DLD and dyslexia. European Portuguese children aged 7-10 years, with DLD (N = 7) or dyslexia (N = 11) were recruited and compared to age-matched typically developing (TD) children (N = 21) on phonological processing, language andf literacy measures. The between-group comparison revealed that for phonological processing, the clinical groups scored significantly below TD children on most tasks, yet the DLD group performed similarly to TD children for RAN speed and digit span. The clinical groups did not statistically differ in their phonological processing abilities. For language abilities, children with dyslexia did not differ from TD children, whilst children with DLD performed significantly below TD children on all measures and significantly below children with dyslexia for vocabulary. Finally, for literacy measures, there were no statistical differences between clinical groups which underperformed on all measures when compared to TD children. The frequency analysis showed that children with DLD exhibited a lower prevalence of RAN difficulties when compared to children with dyslexia, whilst children with DLD tended to show more frequent nonword repetition and phoneme deletion deficits. Additionally, whilst children with DLD consistently showed more prevalent language impairments, both clinical groups demonstrated similar prevalence rates of literacy deficits compared to TD children.These findings lend support to the additional deficit model as children with DLD show more severe and prevalent language impairments than those with dyslexia, despite similar phonological and literacy difficulties.

Understanding Dyslexia in the Context of Developmental Language Disorders

Purpose

The purpose of this tutorial is to discuss the language basis of dyslexia in the context of developmental language disorders (DLDs). Whereas most studies have focused on the phonological skills of children with dyslexia, we bring attention to broader language skills.

Method

We conducted a focused literature review on the language basis of dyslexia from historical and theoretical perspectives with a special emphasis on the relation between dyslexia and DLD and on the development of broader language skills (e.g., vocabulary, syntax, and discourse) before and after the identification of dyslexia.

Results

We present clinically relevant information on the history of dyslexia as a language-based disorder, the operational definitions used to diagnose dyslexia in research and practice, the relation between dyslexia and DLD, and the language abilities of children with dyslexia.

Conclusions

We discuss 3 clinical implications for working with children with dyslexia in school settings: (a) Children with dyslexia—with and without comorbid DLDs—often have language deficits outside the phonological domain; (b) intervention should target a child's strengths and weaknesses relative to reading outcomes, regardless of diagnostic labels; and (c) those who have dyslexia, regardless of language abilities at the time of diagnosis, may be at risk for slower language acquisition across their lifetime. Longitudinal studies are needed to assess multiple language skills early, at the time of the diagnosis of dyslexia, and years later to better understand the complex development of language and reading in children with dyslexia.

Differences in Errors Between Students With Language and Reading Disabilities

Children with a specific learning disability in reading/writing (LDRW) and/or language impairment (LI) are likely to have difficulties across all areas of academic achievement, as a great deal of teaching and learning depends on intact reading skill and linguistic communication. Despite a large number of studies examining academic difficulties among these groups, there has been minimal research investigating types of errors made on tests of academic achievement. The present study compared academic error types of children with LDRW (Group 1) and children with LI (Group 3) to two distinct demographically matched control groups (Groups 2 and 4) using the Kaufman Test of Educational Achievement–Third Edition (KTEA-3) error analysis system. Findings indicate that children in the LDRW group or LI group, on average, made a greater number of errors than their matched counterparts. Statistically significant differences, with moderate effect sizes, were found between examinees in the clinical groups and their respective matched control groups across several error categories. Some of the largest differences were found in the Written Expression and Oral Expression subtests. Most importantly, the patterns of errors made by LDRW and LI samples differed notably on the various tasks, providing new insights about these clinical samples.

Specific language impairment and developmental dyslexia: What are the boundaries? Data from Greek children

This study examines the significance (between-groups comparisons) and frequency (within-group analyses) of deficits in developmental dyslexia (DD, mainly deficits in decoding and phonemic awareness), specific language impairment (SLI, mainly deficits in listening comprehension), or both (mainly deficits in phonological short-term memory [STM]). Participants included two groups of children who had received a diagnosis of either SLI (N=15) or DD (N=15). For the between-groups comparison, the groups were matched pairwise on nonverbal IQ to 30 chronological age controls (CAC) and 30 reading level controls (RLC). For the within-group analyses, the participants were compared to 91 CACs and 63 RLCs. We developed tasks not used for the diagnoses to assess phonological skills (decoding, phonemic awareness, phonological STM) and non-phonological skills (listening and reading comprehension). SLI children scored lower than both DD children and RLCs on tasks assessing listening and reading comprehension, and lower than RLCs on phonological STM and phonemic awareness. Within-group comparisons showed that a higher proportion of SLI than DD children presented severe deficits in the same four domains. The opposite pattern was found for decoding skills (7 SLI children with a severe deficit, versus 13 in the DD group). These findings are discussed in the light of models explaining the overlap between SLI and DD. They highlight the need to assess both phonological and non-phonological skills in SLI and DD children, using both between- and within-groups designs.