A review of the neurobiological basis of dyslexia in the adult population

A volumetric asymmetry study of gray matter in individuals with and without dyslexia

Brain imaging work aimed at increased classification of dyslexia has underscored an important relationship between anterior (i.e., the inferior frontal gyrus; IFG) and posterior (i.e., superior temporal gyrus and supramarginal gyrus) brain regions. The extent to which the three components of the inferior frontal gyrus, namely the pars orbitalis, triangularis, and opercularis, are differentially related to the posterior regions, namely the superior temporal gyrus and supramarginal gyrus, needs further elucidation. Information about the nature of the anterior-posterior connections would facilitate our understanding of the neural underpinnings associated with dyslexia. Adult participants (N = 38; 16 with dyslexia) took part in an MRI study, whereby high-resolution structural scans were obtained. Volumetric asymmetry of the three regions of the IFG, the superior temporal gyrus, and the supramarginal gyrus was extracted. Significant differences were found for each of the three IFG regions, such that skilled readers had a greater leftward asymmetry of the orbitalis and triangularis, and greater rightward asymmetry of the opercularis, when compared to individuals with dyslexia. Furthermore, the pars triangularis was significantly associated with leftward asymmetry of the superior temporal gyrus for skilled but not dyslexic participants. For individuals with dyslexia, the cortical asymmetry of the IFG, and the corresponding connections with other reading-related brain regions, is inherently different from skilled readers. We discuss our findings in the context of the print-to-speech framework to further our understanding of the neural underpinnings associated with dyslexia.

Psychoeducational Challenges in Spanish Children With Dyslexia and Their Parents' Stress During the COVID-19 Pandemic

Background

Research during 2020 has been rapidly attending to the impact of COVID-19 on various dimensions of wellbeing (e.g., physical, psychological, lifestyle and routines) on adults and children around the world. However, less attention has focused on the psychoeducational impact on children and their families. To our knowledge, no currently available studies have looked specifically at the impact of COVID-19 on students with dyslexia and their families. Research on this topic is needed to offer greater support for this population of students and their families.

Objective

The main objective of this paper is to examine the psychoeducational impact of the required COVID-19 quarantine in Spain among children with dyslexia and their families.

Method

A sample of 32 children with dyslexia and their mothers participated in this study.

Measures

Children and adolescents with dyslexia and their mother completed several measures before the required national quarantine in Spain and again during the quarantine. Children completed measures of depression, state anxiety, reading activity, and reading motivation. Mothers provided demographic information and completed measures related to students’ emotional and behavioral difficulties as well as parenting stress, parental distress, and a questionnaire about educational problems during quarantine.

Results

Major findings showed that during quarantine, children with dyslexia had increased levels of depression and anxiety symptoms, and parents perceived their children as having more emotional symptoms, hyperactivity-inattention, and conduct problems. During quarantine, children and adolescents with dyslexia also showed less reading activity and less reading motivation. Parents also reported significantly more stress, during quarantine compared to pre-quarantine conditions. Some demographic and psychological variables predicted children’s state anxiety as well parental stress. The questionnaire related to impacts of quarantine also revealed several important findings. For example, nearly all parents of children with dyslexia reported (a) difficulties in establishing study routines, (b) that the quarantine negatively affected their child’s learning, and (c) that they did not receive sufficient help from teachers on how to support their child’s learning. Additionally, the vast majority of the parents were very worried about the child’s learning and school success, the child’s motivation and interest in reading, the child’s peer relations, and the professional skills of the child’s teacher.

Conclusion

This study offers a preliminary investigation into this topic and elucidates several psychoeducational challenges that children with dyslexia and their families have experienced during the quarantine in Spain. Study findings highlight the need to provide immediate support for children with dyslexia and emphasizes the importance of developing prevention programs to mitigate any future negative impacts of COVID-19 on children with dyslexia and their parents.

A pilot Indian family-based association study between dyslexia and Reelin pathway genes, DCDC2 and ROBO1, identifies modest association with a triallelic unit TAT in the gene RELN

Dyslexia is a neurodevelopmental disorder that manifests as a reading disability despite normal intelligence and adequate educational opportunity. Twin and family studies have indicated a genetic component, while genome-wide studies have implicated a number of susceptibility genes, most of which have direct or indirect roles in neuronal migration. Reelin (RELN) has important biological functions facilitating migration of neurons. Polymorphisms in RELN have been implicated in related disorders like autism and schizophrenia but have not been examined in dyslexia. We hypothesized that not only RELN, but its interactors in the neuronal migration pathway may play roles in the etiology of dyslexia. Twenty two functional variants across six RELN signalling genes (RELN, VLDLR, APOER2, DAB1, LIS1 and NDEL1) and two dyslexia candidate genes (DCDC2 and ROBO1) were analyzed for association in twenty six nuclear and three extended families with individuals affected with dyslexia. Univariate association analysis was suggestive of association (puncorrected = 0.01) with rs362746 in RELN which however did not withstand Bonferroni corrections (pcorrected = 0.21). Multimarker tests indicated significant association (p = 0.037), based on which we tested for haplotype associations. Although there were no significant haplotypic associations, we found that a three marker unit with rs3808039 and rs2072403 flanking and independently in linkage disequilibrium with rs362746 was significantly overtransmitted (risk allelic combination - TAT) to dyslexia affected individuals in the sample (p = 0.002). Our results suggest preliminary evidence for a new potential risk variant in the RELN locus for dyslexia.

Knowledge and beliefs about developmental dyslexia in pre-service and in-service Spanish-speaking teachers

The present study investigated knowledge, misconceptions, and lack of information about dyslexia among pre-service (PST) and in-service (IST) Spanish-speaking teachers in Spain and Peru. Two hundred and forty-six pre-service teachers and 267 in-service teachers completed the Knowledge and Beliefs about Developmental Dyslexia Scale (KBDDS). In-service teachers scored significantly higher on the total scale, and on the symptoms/diagnosis and general information subscales, than pre-service teachers. The percentages for misconceptions and lack of information ("do not know responses") were higher for PSTs than for ISTs on the general information subscale, the symptoms/diagnosis subscale, and the treatment subscale. Analyses of individual items were conducted to differentiate concepts that teachers did not know from misconceptions. In-service teacher self-efficacy, years of teaching experience, post-graduate training in dyslexia, and prior exposure to a child with dyslexia were positively related to knowledge about dyslexia. Implications for pre-service teacher training and professional development are discussed.