Explaining the sex difference in dyslexia

Abstract

Background Males are diagnosed with dyslexia more frequently than females, even in epidemiological samples. This may be explained by greater variance in males’ reading performance. Methods We expand on previous research by rigorously testing the variance difference theory, and testing for mediation of the sex difference by cognitive correlates. We developed an analytic framework that can be applied to group differences in any psychiatric disorder. Results Males’ overrepresentation in the low performance tail of the reading distribution was accounted for by mean and variance differences across sex. There was no sex difference at the high performance tail. Processing speed and inhibitory control partially mediated the sex difference. Verbal reasoning emerged as a strength in males. Conclusions Our results complement a previous finding that processing speed partially mediates the sex difference in symptoms of attention deficit/hyperactivity disorder (ADHD), and helps explain the sex difference in both dyslexia and ADHD and their comorbidity.

Developmental Outcomes for Children at High Risk of Dyslexia and Children With Developmental Language Disorder

“…Of the children with dyslexia, some 76% had significant language difficulties at 5½ years shortly after entering school, in line with the “critical age hypothesis” (Bishop & Adams, ). We also found increased vulnerability for both dyslexia and DLD in boys (Arnett et al., ; Rutter et al., ), and it is notable that children with DLD (regardless of dyslexia status) are of lower SES than children with dyslexia and typical readers (though their difference from the dyslexia‐only group is not statistically significant).…”

Gross Motor Skills Performance in Children with Dyslexia: A Comparison between Younger and Older Children

“…This study found that there are more male than female children with dyslexia. This finding is similar with previous studies, where a higher prevalence of dyslexia was found in male children (Arnett et al 2017;Badalà et al 2008;Rosana Awang Bolhasan 2009). The Voxel-Based Morphometry (VBM), a technique done by manual tracing to examine the brain anatomy in MRI was employed to prove the abnormalities in the brain, which usually done on male children (Badalà et al 2008).…”

Men and women differ in the neural basis of handwriting

“…Finally, our findings have methodological implications for neuroscience research of handwriting, supporting the view that sex differences should be taken into account in neuroscience research studies (Bale & Epperson, ; McCarthy, Woolley, & Arnold, ). For example, some handwriting‐related disorders have been found to show strong male prevalence, such as dysgraphia (Karlsdottir & Stefansson, ) and dyslexia (Arnett et al, ). The results from group comparisons in language and motor experiments might be biased by sex differences if the number of male and female participants is not controlled.…”