Brain anatomy of dyslexia is not the same in men and women, boys and girls
Using MRI, neuroscientists at Georgetown University Medical Center found significant differences in brain anatomy when comparing men and women with dyslexia to their non-dyslexic control groups, suggesting that the disorder may have a different brain-based manifestation based on sex.
Their study, investigating dyslexia in both males and females, is the first to directly compare brain anatomy of females with and without dyslexia (in children and adults). Their findings were published online in the journal Brain Structure and Function.
Because dyslexia is two to three times more prevalent in males compared with females, “females have been overlooked,” says senior author Guinevere Eden, PhD, director for the Center for the Study of Learning and past-president of the International Dyslexia Association.
“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,” Eden says.
Previous work outside of dyslexia demonstrates that male and female brains are different in general, adds the study’s lead author, Tanya Evans, PhD.
“There is sex-specific variance in brain anatomy and females tend to use both hemispheres for language tasks, while males just the left,” Evans says. “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.”
What is dyslexia?
Dyslexia has been around for a long time and has been defined in different ways. For example, in 1968, the World Federation of Neurologists defined dyslexia as “a disorder in children who, despite conventional classroom experience, fail to attain the language skills of reading, writing, and spelling commensurate with their intellectual abilities.” According to the U.S. National Institutes of Health, dyslexia is a learning disability that can hinder a person’s ability to read, write, spell, and sometimes speak. Dyslexia is the most common learning disability in children and persists throughout life. The severity of dyslexia can vary from mild to severe. The sooner dyslexia is treated, the more favorable the outcome; however, it is never too late for people with dyslexia to learn to improve their language skills.
Children with dyslexia have difficulty in learning to read despite traditional instruction, at least average intelligence, and an adequate opportunity to learn. It is caused by an impairment in the brain’s ability to translate images received from the eyes or ears into understandable language. It does not result from vision or hearing problems. It is not due to mental retardation, brain damage, or a lack of intelligence.
Dyslexia can go undetected in the early grades of schooling. The child can become frustrated by the difficulty in learning to read, and other problems can arise that disguise dyslexia. The child may show signs of depression and low self-esteem. Behavior problems at home as well as at school are frequently seen. The child may become unmotivated and develop a dislike for school. The child’s success in school may be jeopardized if the problem remains untreated.
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 the males, less gray matter volume is found in dyslexics in areas of the brain used to process language, consistent with previous work. In the females, less gray matter volume is found in dyslexics in areas involved in sensory and motor processing.
How Is Dyslexia Treated?
It helps to identify dyslexia as early in life as possible. Adults with unidentified dyslexia often work in jobs below their intellectual capacity. But with help from a tutor, teacher, or other trained professional, almost all people with dyslexia can become good readers and writers. Use the following strategies to help to make progress with dyslexia.
Expose your child to early oral reading, writing, drawing, and practice to encourage development of print knowledge, basic letter formation, recognition skills, and linguistic awareness (the relationship between sound and meaning).
Have your child practice reading different kinds of texts. This includes books, magazines, ads, and comics.
Include multi-sensory, structured language instruction. Practice using sight, sound, and touch when introducing new ideas.
Seek modifications in the classroom. This might include extra time to complete assignments, help with note taking, oral testing, and other means of assessment.
Use books on tape and assistive technology. Examples are screen readers and voice recognition computer software.
Get help with the emotional issues that arise from struggling to overcome academic difficulties.
Reading and writing are key skills for daily living. However, it is important to also emphasize other aspects of learning and expression. Like all people, those with dyslexia enjoy activities that tap into their strengths and interests. For example, people with dyslexia may be attracted to fields that do not emphasize language skills. Examples are design, art, architecture, engineering, and surgery.
The results have important implications for understanding the origin of dyslexia and the relationship between language and sensory processing, says Evans.
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The research funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (P50HD40095 and R01HD05610701), by the National Center for Advancing Translational Sciences (UL1TR000101) and the National Science Foundation (SBE0541953 Science of Learning Center).
The authors report having no personal financial interests related to the study.
About Georgetown University Medical Center
Georgetown University Medical Center is an internationally recognized academic medical center with a three-part mission of research, teaching and patient care (through Georgetown’s affiliation with MedStar Health). GUMC’s mission is carried out with a strong emphasis on public service and a dedication to the Catholic, Jesuit principle of cura personalis—or “care of the whole person.” The Medical Center includes the School of Medicine and the School of Nursing and Health Studies, both nationally ranked, the world-renowned Lombardi Comprehensive Cancer Center and the Biomedical Graduate Research Organization (BGRO), home to 60 percent of the university’s sponsored research funding.
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Karen Mallet
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Georgetown University Medical Center