When comparing men and women who have dyslexia to non-dyslexic control groups, researchers found significant differences in brain anatomy, suggesting that the disorder may have a different brain-based manifestation when it comes to gender.
Dyslexia is two to three times more prevalent in males than females and the authors say this is the first study to directly compare brain anatomy of females with and without dyslexia (in children and adults). Male and female brains are different in general.
The study of 118 participants compared the brain structure of people with dyslexia to those without and was conducted separately in men, women, boys and girls.
In males, less gray matter volume was found in dyslexics in the areas of the brain used to process language, consistent with previous work. In females, less gray matter volume was found in dyslexics in areas involved in sensory and motor processing.
"It has been assumed that results of studies conducted in men are generalizable to both sexes. But our research suggests that researchers need to tackle dyslexia in each sex separately to address questions about its origin and potentially, treatment,"
says senior author Guinevere Eden, PhD, director for the Center for the Study of Learning
at Georgetown University Medical Center
and past-president of the International Dyslexia Association.
"There is sex-specific variance in brain anatomy and females tend to use both hemispheres for language tasks, while males just the left," says the study's lead author, Tanya Evans, PhD. "It is also known that sex hormones are related to brain anatomy and that female sex hormones such as estrogen can be protective after brain injury, suggesting another avenue that might lead to the sex-specific findings reported in this study."
The results have important implications for understanding the origin of dyslexia and the relationship between language and sensory processing, says Evans.
Published in Brain Structure and Function.