Article

Sex-specific gray matter volume differences in females with developmental dyslexia.

Center for the Study of Learning, Department of Pediatrics, Georgetown University Medical Center, BOX 571406, Suite 150, Building D, 4000 Reservoir Road, NW, Washington, DC, 20057, USA.
Brain Structure and Function (Impact Factor: 7.84). 04/2013; 219(3). DOI: 10.1007/s00429-013-0552-4
Source: PubMed

ABSTRACT Developmental dyslexia, characterized by unexpected reading difficulty, is associated with anomalous brain anatomy and function. Previous structural neuroimaging studies have converged in reports of less gray matter volume (GMV) in dyslexics within left hemisphere regions known to subserve language. Due to the higher prevalence of dyslexia in males, these studies are heavily weighted towards males, raising the question whether studies of dyslexia in females only and using the same techniques, would generate the same findings. In a replication study of men, we obtained the same findings of less GMV in dyslexics in left middle/inferior temporal gyri and right postcentral/supramarginal gyri as reported in the literature. However, comparisons in women with and without dyslexia did not yield left hemisphere differences, and instead, we found less GMV in right precuneus and paracentral lobule/medial frontal gyrus. In boys, we found less GMV in left inferior parietal cortex (supramarginal/angular gyri), again consistent with previous work, while in girls differences were within right central sulcus, spanning adjacent gyri, and left primary visual cortex. Our investigation into anatomical variants in dyslexia replicates existing studies in males, but at the same time shows that dyslexia in females is not characterized by involvement of left hemisphere language regions but rather early sensory and motor cortices (i.e., motor and premotor cortex, primary visual cortex). Our findings suggest that models on the brain basis of dyslexia, primarily developed through the study of males, may not be appropriate for females and suggest a need for more sex-specific investigations into dyslexia.

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    ABSTRACT: Some arithmetic procedures, such as addition of small numbers, rely on fact retrieval mechanisms supported by left hemisphere perisylvian language areas, while others, such as subtraction, rely on procedural-based mechanisms subserved by bilateral parietal cortices. Previous work suggests that developmental dyslexia, a reading disability, is accompanied by subtle deficits in retrieval-based arithmetic, possibly because of compromised left hemisphere function. To test this prediction, we compared brain activity underlying arithmetic problem solving in children with and without dyslexia during addition and subtraction operations using a factorial design. The main effect of arithmetic operation (addition versus subtraction) for both groups combined revealed activity during addition in the left superior temporal gyrus and activity during subtraction in the bilateral intraparietal sulcus, the right supramarginal gyrus and the anterior cingulate, consistent with prior studies. For the main effect of diagnostic group (dyslexics versus controls), we found less activity in dyslexic children in the left supramarginal gyrus. Finally, the interaction analysis revealed that while the control group showed a strong response in the right supramarginal gyrus for subtraction but not for addition, the dyslexic group engaged this region for both operations. This provides physiological evidence in support of the theory that children with dyslexia, because of the disruption to left hemisphere language areas, use a less optimal route for retrieval-based arithmetic, engaging right hemisphere parietal regions typically used by good readers for procedural-based arithmetic. Our results highlight the importance of language processing for mathematical processing and illustrate that children with dyslexia have impairments that extend beyond reading.
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    12/2013, Degree: PhD, Supervisor: Ayman El-Baz
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    ABSTRACT: Objectives: Strong self-esteem is related to good psychological health. Dyslexia has a negative effect on self-esteem, but this effect depends on support levels at home and/or school. Women with dyslexia are an under investigated group, and it has been suggested that female dyslexics should be given special attention from teachers with a view to improving their self-esteem. This paper set out to compare levels of self-esteem in women with dyslexia and normative women, and to investigate relationships between dyslexic problems and self-esteem. Method: It was hypothesized that women with dyslexia would have a weaker self-esteem. We have assessed dyslexia, using a Swedish battery of standardised pedagogical, IQ, and neuropsychological tests, and the self-esteem of twelve young women (mean age 19 years; range 16-30), using a Swedish questionnaire that distinguishes between different dimensions of self-esteem (physical characteristics, talents and gifts, psychological health, relationships with parents and family, and relationships with others). Comparative (t-tests) and correlational (Pearson’s correlations and stepwise multiple regression analyses) statistical methods were performed. Results: The study subjects had a weaker self-esteem than that of a normative sample of females (N = 313) in all dimensions, except for the dimension of relationships with parents and family. Spelling ability was related to “Physical characteristics” (negative) and to “Relations with parents and family” (positive). Moreover, speed of reading was related to “Psychological health” (positive). Conclusions: The use of questionnaires that distinguish between different dimensions of self-esteem and a larger sample is recommended in future studies.

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May 22, 2014