Brain Study Shows Dyslexia Impacts Mathematical Processing

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WASHINGTON (Sept. 12, 2014) – In the first known study of its kind, researchers have identified brain activity that links dyslexia to difficulty with math. The findings from the Georgetown University Medical Center study are published in the Nov. 1 issue of the journal Neuroimage, now online.

People typically associate dyslexia with reading problems. However, those with dyslexia can also struggle with specific math problems, even though they may not meet the criteria for a formal math disability diagnosis (dyscalculia). The researchers say the finding has important ramifications for recognizing the wide spread repercussions of dyslexia.

“It is known that the incidence of math disability is higher in children who have a reading disability,” says senior author Guinevere Eden, PhD, director of Center for the Study of Learning at Georgetown University Medical Center. “It has also become clear that specific aspects of arithmetic – those involving retrieval of verbal information – are difficult for children and adults with dyslexia.”  

To understand this relationship between math performance and reading disability, the researchers had to go beyond studying children’s behavior and take a closer look at their patterns of brain activity while doing math.  

“Children without dyslexia show more activity for subtraction compared with addition in the right intraparietal sulcus, a region known to be important for calculation,” says lead author Tanya Evans, PhD, now a fellow at Stanford University School of Medicine. “Children with dyslexia show equal activity in this region, suggesting they are using a similar strategy to perform these different tasks. This strategy is probably not ideal and a reason for the previously observed poorer performance during addition.”  

The findings highlight that reading is not the only skill affected by dyslexia, which has important implications for education. Previous work looking at performance measures has demonstrated this weakness in people with dyslexia for math problems that are normally solved through fact retrieval (e.g., small digit addition and multiplication, such as 2+3, or 5×5), relative to those more likely to be solved using formulas or other strategies (e.g., subtraction, division).  

“This could impact the strategies used for interventions to target this common learning disability,” says Eden. “Interventions targeting verbal retrieval may be helpful in bolstering arithmetic skills in children that struggle with reading.”

The research was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (P50HD40095 and R01HD05610701), 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.