Dyslexia with and without Irlen syndrome: A study of influence on abilities and brain‐derived neurotrophic factor level

Abstract The presence of comorbid Irlen syndrome (IS) in children with developmental dyslexia (DD) may have an impact on their reading and cognitive abilities. Furthermore, the brain‐derived neurotrophic factor (BDNF) was reported to be expressed in brain areas involved in cognitive and visual processing. The aim of this study was to evaluate some cognitive abilities of a group of dyslexic children with IS and to measure and compare the plasma BDNF level to dyslexic children without IS and neurotypical (NT) children. The participants were 60 children with DD (30 in the DD + IS group; 30 in the DD group) and 30 NT children. The Irlen reading perceptual scale, the Stanford Binet intelligence scale, 4th ed, the dyslexia assessment test, and the Illinois test of psycholinguistic abilities were used. The BDNF level was measured using the enzyme‐linked immunosorbent assay. One‐minute writing and visual closure deficits were more prevalent, while phonemic segmentation deficits were less prevalent in the DD + IS group compared to the DD group. The BDNF level in the DD groups was lower than that in NT children (p < 0.001). Some reading and non‐reading tasks were influenced by the presence of a coexisting IS. The reduced BDNF level could play a role in the deficits noticed in the abilities of children with DD

Brain morphology in autism and fragile x syndrome correlates with social IQ: First report from the Canadian-Swiss-Egyptian Neurodevelopmental Study (CSENS)

Fragile x syndrome shares most of the behavioral phenotypic similarities with autism. How are these similarities reflected in brain morphology? Ten children with autism and seven with fragile x underwent morphological (T1) 1.5T magnetic resonance imaging. We found no significant difference in total brain volumes, regional volumes, gyrification index, sulcul depth and cerebral cortical thickness. However, children with autism showed significant decrease in the medial prefrontal bilaterally and the left anterior cingulate cortices. Regression analysis revealed positive correlation between the medial prefrontal cortical thickness and social IQ. We suggest that the difference between the two groups in the medial prefrontal and anterior cingulate cortices thickness may entail an altered social cognitive style. Functional magnetic resonance imaging studies directly differentiating between social indifference (autism) and social avoidance (fragile x) are needed in order to further characterize the spectrum of social abnormalities between these two groups. Key words: autism, fragile x syndrome, magnetic resonance imaging, cerebral cortical thickness, medial prefrontal, anterior cingulate