Although dyslexia is the most common learning disorder in children, it has not received adequate attention in Saudi Arabia.
This study aimed at determining the prevalence of dyslexia among Saudi ...students in Grades 3–6, exploring associations between severity of dyslexia, its behavioral indicators, gender and grade, and the moderating role of grade in the relationship between severity and behavioral indicators.
The sample consisted of 2848 female students and 2647 male students in Zulfi governorate, Saudi Arabia. A survey-based mixed-methods design was chosen including a structured interview with teachers and three assessments using the Diagnostic Assessment Scale for Dyslexia, the Arabic Reading Test, and the Dyslexia Behavioral Indicators Scale.
Dyslexia was assessed in 5.86 % of the total sample. It was twice as prevalent among male students as among female students (6.54 % and 3.83 %, respectively). The mean score for behavioral indicators of dyslexia was also significantly higher for male than for female students. The correlation between dyslexia severity and behavioral indicators score was high and significant, with grade level as a significant moderator.
We found that, for children with dyslexia in Saudi Arabia, dyslexia was twice as prevalent among male students as among female students. Early dyslexia diagnosis and intervention services are suggested to reduce the risk for reading problems.
•This research yields a better understanding of the role of grade progression on the relationship between severity of dyslexia and its behavioral indicators.•This research showed that in children with dyslexia in Saudi Arabia, the dyslexia was twice as prevalent among male students as among female students.•The behavioral indictors of dyslexia were higher in male students than in female students•Correlations between dyslexia severity and behavioral indicators were higher for female than male students•The results indicate that as the student grade level increased the negative relationship between dyslexia severity and behavioral indicators of dyslexia decreased.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Reading training is related to an increased reading ability in children.•Greater “gains” in reading were related with low GLX concentrations for children with dyslexia.•This study ...supports the extension of the neural noise hypothesis in dyslexia.
The “neural noise” hypothesis suggests that individuals with dyslexia have high glutamate concentrations associated with their reading challenges. Different reading intervention programs have showed low GLX (a combined measure for glutamine and glutamate obtained with in vivo magnetic resonance spectroscopy) in association with reading improvement. Several studies demonstrated improved reading and increased activation in the anterior cingulate cortex following an-executive-function (EF)-based reading intervention. The goals of the current study are two-fold: 1) to determine if the effect of the EF-based reading program extends also to the metabolite concentrations and in particular, on the GLX concentrations in the anterior cingulate cortex; 2) to expand the neural noise hypothesis in dyslexia also to neural networks supporting additional parts of the reading networks, i.e. in specific regions related to executive function skills.
Children with dyslexia and typical readers were trained on the EF-based reading program. Reading ability was assessed before and after training while spectroscopy data was obtained at the end of the program. The association between change in reading scores following intervention and GLX concentrations was examined.
Greater “gains” in word reading were associated with low GLX, Glu, Cr, and NAA concentrations for children with dyslexia compared to typical readers.
These results suggest that the improvement reported following the EF-based reading intervention program also involved a low GLX concentration, as well as additional metabolites previously associated with better reading ability (Glx, Cr, NAA) which may point at the decreased neural noise, especially in the anterior cingulate cortex, as a possible mechanism for the effect of this program.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Background
This study considers the role of early speech difficulties in literacy development, in the context of additional risk factors.
Method
Children were identified with speech sound disorder ...(SSD) at the age of 3½ years, on the basis of performance on the Diagnostic Evaluation of Articulation and Phonology. Their literacy skills were assessed at the start of formal reading instruction (age 5½), using measures of phoneme awareness, word‐level reading and spelling; and 3 years later (age 8), using measures of word‐level reading, spelling and reading comprehension.
Results
The presence of early SSD conferred a small but significant risk of poor phonemic skills and spelling at the age of 5½ and of poor word reading at the age of 8. Furthermore, within the group with SSD, the persistence of speech difficulties to the point of school entry was associated with poorer emergent literacy skills, and children with ‘disordered’ speech errors had poorer word reading skills than children whose speech errors indicated ‘delay’. In contrast, the initial severity of SSD was not a significant predictor of reading development. Beyond the domain of speech, the presence of a co‐occurring language impairment was strongly predictive of literacy skills and having a family risk of dyslexia predicted additional variance in literacy at both time‐points.
Conclusions
Early SSD alone has only modest effects on literacy development but when additional risk factors are present, these can have serious negative consequences, consistent with the view that multiple risks accumulate to predict reading disorders.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Developmental dyslexia (decoding-based reading disorder; RD) is a complex trait with multifactorial origins at the genetic, neural, and cognitive levels. There is evidence that low-level ...sensory-processing deficits precede and underlie phonological problems, which are one of the best-documented aspects of RD. RD is also associated with impairments in integrating visual symbols with their corresponding speech sounds. Although causal relationships between sensory processing, print–speech integration, and fluent reading, and their neural bases are debated, these processes all require precise timing mechanisms across distributed brain networks. Neural excitability and neural noise are fundamental to these timing mechanisms. Here, we propose that neural noise stemming from increased neural excitability in cortical networks implicated in reading is one key distal contributor to RD.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Some researchers suggest that deficits in attention and working memory influence the development of dyslexia, whereas others propose that these deficits are more likely due to reduced global ...processing speed. The current study aimed to investigate behavioral performance in children with dyslexia compared to typically developing controls on two tasks: a visual oddball task for attention and an n-back task for working memory. We measured P300 event-related potentials (ERP) amplitude and latency for both tasks. Our results demonstrated reduced behavioral accuracy and P300 amplitude for the children with dyslexia compared to their typically developing peers in both the n-back and visual oddball tasks. We also found no differences in response time or P300 latency between these groups on either task. These findings support the idea that children with dyslexia experience deficits in cognitive processes related to working memory and attention, but do not exhibit decreased global processing speed on these tasks.
•Chinese dyslexia is not characterized by a single deficit.•Good and dyslexic readers differed in all the behavioral measures used in the study.•Particularly, they differed in phonological awareness ...with large effect size.•But poor phonological skill was not necessary or sufficient for Chinese dyslexia.•We did not find any factor to be necessary or sufficient for Chinese dyslexia.
While phonological skills have been found to be correlated with reading across different writing systems, recent findings have shown that developmental dyslexia in Chinese individuals has multiple deficits, and no single factor has ever been identified as crucial for learning this writing system. To examine whether a deficit in the phonological or another cognitive domain is a necessary or sufficient condition for Chinese reading disability, this study examined the cognitive profiles of 521 good readers and 502 dyslexic readers in Chinese primary schools using a battery of behavioral measures covering phonological, visual, orthographic, visual-motor coordination and working memory skills. The results showed that among all cognitive measures, phonological skills correlated more strongly with character reading performance but that poor phonological skills did not necessarily or sufficiently lead to poor reading performance in Chinese.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Pou6f2 is a genetic connection between central corneal thickness (CCT) in the mouse and a risk factor for developing primary open-angle glaucoma. POU6F2 is also a risk factor for several conditions ...in humans, including glaucoma, myopia, and dyslexia. Recent findings demonstrate that POU6F2-positive retinal ganglion cells (RGCs) comprise a number of RGC subtypes in the mouse, some of which also co-stain for Cdh6 and Hoxd10. These POU6F2-positive RGCs appear to be novel of ON-OFF directionally selective ganglion cells (ooDSGCs) that do not co-stain with CART or SATB2 (typical ooDSGCs markers). These POU6F2-positive cells are sensitive to damage caused by elevated intraocular pressure. In the DBA/2J mouse glaucoma model, heavily-labeled POU6F2 RGCs decrease by 73% at 8 months of age compared to only 22% loss of total RGCs (labeled with RBPMS). Additionally, Pou6f2
mice suffer a significant loss of acuity and spatial contrast sensitivity along with an 11.4% loss of total RGCs. In the rhesus macaque retina, POU6F2 labels the large parasol ganglion cells that form the magnocellular (M) pathway. The association of POU6F2 with the M-pathway may reveal in part its role in human glaucoma, myopia, and dyslexia.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Despite advances in the characterization of developmental dyslexia (DD), several questions regarding the interplay between DD-susceptibility genes and environmental risk factors remain open. This ...systematic review aimed at answering the following questions: What has been the impact of new resources on the knowledge about DD? Which questions remain open? What is the investigative agenda for the short term? Forty-six studies were analyzed. Despite the growing literature on DD candidate genes, most studies have not been replicated. We found large effects on causative genes and smaller environmental contributions, involving maternal smoking during pregnancy, SES and the DYX1C1-1259C/G marker. Implications are discussed.
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Phonological awareness, knowledge that speech is composed of syllables and phonemes, is critical for learning to read. Phonological awareness precedes and predicts successful transition from language ...to literacy, and weakness in phonological awareness is a leading cause of dyslexia, but the brain basis of phonological awareness for spoken language in children is unknown. We used functional magnetic resonance imaging to identify the neural correlates of phonological awareness using an auditory word-rhyming task in children who were typical readers or who had dyslexia (ages 7-13) and a younger group of kindergarteners (ages 5-6). Typically developing children, but not children with dyslexia, recruited left dorsolateral prefrontal cortex (DLPFC) when making explicit phonological judgments. Kindergarteners, who were matched to the older children with dyslexia on standardized tests of phonological awareness, also recruited left DLPFC. Left DLPFC may play a critical role in the development of phonological awareness for spoken language critical for reading and in the etiology of dyslexia.
Highlights • Organization of brain networks in dyslexics and typically-reading controls. • Minimum spanning tree (MST) graphs were derived from connectivity matrices. • Graph metrics in the ...theta-band showed less integrated network configuration in dyslexics.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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