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

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.

Language development in rural and urban Russian-speaking children with and without developmental language disorder

“…The second finding is more difficult to explain in the context of reports of increased prevalence of DLD among boys compared to girls (Shriberg, Tomblin, & McSweeny, 1999; Tomblin et al, 1997). However, it is possible that it reflects the sex specificity of the etiological mechanisms underlying the manifestation of DLD, as has, for example, been suggested for other communication and learning disorders (e.g., Evans, Flowers, Napoliello, & Eden, 2014; Suresh et al, 2006). …”

The functional anatomy of single-digit arithmetic in children with developmental dyslexia

“…The subjects were a subset of a group of children participating in a larger study on reading, reading disability, and reading development (Evans et al, 2013; Krafnick et al, 2014; Krafnick et al, 2011; Olulade et al, 2013a; Olulade et al, 2013b). Subjects with developmental dyslexia had a documented history of their reading disability, and most attended a school that specializes in the teaching of children with learning disabilities.…”

Effects of Physical Rotational Movement Difference and Handwriting Position on Academic Achievement and Learning Disabilities

“…In the present study, all 7 LD-identified students were male and in the exclusive top left and inverted bimanual groups. While suggestive, it is still unclear whether or not a gender difference related to this particular bimanual rotation laterality exists; new research identifying female dyslexia may contribute to this finding (Evans et al, 2013).…”