Language Difficulties in School-Age Children With Developmental Dyslexia

Revisiting the definition of dyslexia

The International Dyslexia Association definition of dyslexia was updated 20 years ago and has been referenced frequently in research and practice. In this paper, researchers from the Florida Center for Reading Research consider the components of the definition and make recommendations for revisions. These include recognizing the persistence of word-reading, decoding, and spelling difficulties, acknowledging the multifactorial causal basis of dyslexia, clarifying exclusionary factors, and denoting comorbidity with other developmental disorders. It is also suggested that the academic and psychosocial consequences of dyslexia be highlighted to reinforce a preventive service delivery model. Lastly, the inclusion of dyslexia within a specific learning disability category is supported.

Vocabulary Diversity in Personal Narratives Produced in Response to the Global TALES Protocol in Dutch-Speaking Students with and without Dyslexia

INTRODUCTION

This study examines whether there are differences in expressive vocabulary between participants with and without dyslexia in personal narratives in response to the Global TALES protocol.

METHODS

22 monolingual Dutch-speaking participants aged 11-16 with dyslexia and 22 age and gender-matched peers without dyslexia were assessed on measures of decoding, reading comprehension, and spelling of words, pseudowords, verbs, and sentences. The participants also produced personal narratives in response to the six prompts contained in the Global TALES protocol. We analyzed the personal narratives for expressive vocabulary and counted the total number of different words (TNDW).

RESULTS

The study revealed a significant relationship between TNDW and reading comprehension (r = 0.45, p = 0.002, BF10 = 17.70), spelling words (r = 0.42, p = 0.005, BF10 = 8.93), and spelling and writing conventions in sentences (r = 0.37, p = 0.016, BF10 = 3.11). The Global TALES protocol was successful in eliciting personal narratives in the Dutch-speaking participants with and without dyslexia. Participants with dyslexia used fewer different words (M = 192.27, SD = 64.37; 95% CI: [151.84-232.71]) compared to peers without dyslexia (M = 265.50, SD = 116.28; 95% CI: [225.06-305.93]; F(1, 42) = 6.68; p = 0.013; η2 = 0.14). When we compared the probability of models, Bayesian factors revealed moderate evidence for group differences in TNDW (BF = 3.94).

CONCLUSION

Our findings indicate that older school-age participants with dyslexia may lag behind their peers in expressive vocabulary in a personal narrative discourse task that is relevant to everyday functioning. The results of this study highlight the relationship between expressive vocabulary and reading comprehension and the importance of the assessment of spoken language skills in children with dyslexia. Reading problems might lead to less advanced spoken language, which in turn may negatively affect the expressive vocabulary growth in individuals with dyslexia.

The importance and challenges of improving early identification of language abilities: a commentary on Gasparini et al. (2023)

Finding early predictors of later language skills and difficulties is fraught with challenges because of the wide developmental variation in language. Gasparini et al. (Journal of Child Psychology and Psychiatry, 2023) aimed to address this issue by applying machine learning methods to parent reports taken from a large longitudinal database (Early Language in Victoria Study). Using this approach, they identify two short, straightforward item sets, taken at 24 and 36 months, that can adequately predict language difficulties when children are 11 years of age. Their work represents an exciting step towards earlier recognition and support for children with Developmental Language Disorder. This commentary highlights the advantages and challenges of identifying early predictors of language in this way, and discusses future directions that can build on this important contribution.

Identification of brain cell types underlying genetic association with word reading and correlated traits

Neuroimaging studies implicate multiple cortical regions in reading ability/disability. However, the neural cell types integral to the reading process are unknown. To contribute to this gap in knowledge, we integrated genetic results from genome-wide association studies for word reading (n = 5054) with gene expression datasets from adult/fetal human brain. Linkage disequilibrium score regression (LDSC) suggested that variants associated with word reading were enriched in genes expressed in adult excitatory neurons, specifically layer 5 and 6 FEZF2 expressing neurons and intratelencephalic (IT) neurons, which express the marker genes LINC00507, THEMIS, or RORB. Inhibitory neurons (VIP, SST, and PVALB) were also found. This finding was interesting as neurometabolite studies previously implicated excitatory-inhibitory imbalances in the etiology of reading disabilities (RD). We also tested traits that shared genetic etiology with word reading (previously determined by polygenic risk scores): attention-deficit/hyperactivity disorder (ADHD), educational attainment, and cognitive ability. For ADHD, we identified enrichment in L4 IT adult excitatory neurons. For educational attainment and cognitive ability, we confirmed previous studies identifying multiple subclasses of adult cortical excitatory and inhibitory neurons, as well as astrocytes and oligodendrocytes. For educational attainment and cognitive ability, we also identified enrichment in multiple fetal cortical excitatory and inhibitory neurons, intermediate progenitor cells, and radial glial cells. In summary, this study supports a role of excitatory and inhibitory neurons in reading and excitatory neurons in ADHD and contributes new information on fetal cell types enriched in educational attainment and cognitive ability, thereby improving our understanding of the neurobiological basis of reading/correlated traits.

Hypothesis-driven genome-wide association studies provide novel insights into genetics of reading disabilities

Reading Disability (RD) is often characterized by difficulties in the phonology of the language. While the molecular mechanisms underlying it are largely undetermined, loci are being revealed by genome-wide association studies (GWAS). In a previous GWAS for word reading (Price, 2020), we observed that top single-nucleotide polymorphisms (SNPs) were located near to or in genes involved in neuronal migration/axon guidance (NM/AG) or loci implicated in autism spectrum disorder (ASD). A prominent theory of RD etiology posits that it involves disturbed neuronal migration, while potential links between RD-ASD have not been extensively investigated. To improve power to identify associated loci, we up-weighted variants involved in NM/AG or ASD, separately, and performed a new Hypothesis-Driven (HD)-GWAS. The approach was applied to a Toronto RD sample and a meta-analysis of the GenLang Consortium. For the Toronto sample (n = 624), no SNPs reached significance; however, by gene-set analysis, the joint contribution of ASD-related genes passed the threshold (p~1.45 × 10-2, threshold = 2.5 × 10-2). For the GenLang Cohort (n = 26,558), SNPs in DOCK7 and CDH4 showed significant association for the NM/AG hypothesis (sFDR q = 1.02 × 10-2). To make the GenLang dataset more similar to Toronto, we repeated the analysis restricting to samples selected for reading/language deficits (n = 4152). In this GenLang selected subset, we found significant association for a locus intergenic between BTG3-C21orf91 for both hypotheses (sFDR q < 9.00 × 10-4). This study contributes candidate loci to the genetics of word reading. Data also suggest that, although different variants may be involved, alleles implicated in ASD risk may be found in the same genes as those implicated in word reading. This finding is limited to the Toronto sample suggesting that ascertainment influences genetic associations.

Predicting Word Reading Deficits Using an App-Based Screening Tool at School Entry

BACKGROUND

Reading is a crucial competence associated with academic development, mental health, and social adaptation. Reading difficulties are often detected at a late stage, with a possible negative impact on long-term reading development and secondary developmental disadvantages. The first manifestations of reading difficulties can be identified by word reading deficits in first and second grade, paving the way for specific interventions. For widespread implementation, instruments must be easy to use and motivating for children.

OBJECTIVES

Development and validation of an economical, well-accepted, and accurate screening tool composed of the domains of phonological information processing, language skills, and non-verbal intelligence in regular school settings.

DESIGN

In 2020, the screening tool was used on a sample of 409 first graders between the second and fifth weeks of school in a one-to-one setting. Additionally, information on parental education and the use of German and/or other languages by the child was collected using a parental questionnaire. A follow-up involving the use of established standardized word reading tests was conducted at the end of the first school year.

RESULTS

A five-variable screening tool consisting of the dimensions of phonological information processing (letter knowledge, rapid naming, and phonological awareness) and linguistic skills (receptive vocabulary and morphosyntax) showed statistical relevance (AUC = 0.78; sensitivity 0.80, specificity 0.74) for predicting word reading problems concerning reading speed (<16th percentile) at the end of first grade, whereas gender, first language, and age of first exposure to the German language did not contribute to the prediction. The instrument was well accepted by the children and screeners and can be administered within an acceptable time frame.

CONCLUSION

Word reading deficits at the end of first grade can be predicted by the use of an app-based screening tool at school entry that includes phonological information processing and language skills. Further validation and assessment of empirical feasibility data are needed to support the screening instrument for German orthography.