A new study challenges previous findings regarding what causes reading problems in children with the common learning disorder dyslexia.
Some researchers have concluded that these reading difficulties are the result of less gray matter in the brain. This new study suggests, however, that less brain tissue is a consequence of poorer reading experiences and not the root cause of reading problems.
Researchers analyzed the brains of children with dyslexia and compared them with two other groups of children: an age-matched group without dyslexia and a group of younger children who had the same reading level as the children with dyslexia.
"This kind of approach allows us to control for both age as well as reading experience," study leader Guinevere Eden, a neuroscientist and professor of pediatrics at Georgetown University Medical Center, said in a medical center news release.
"If the differences in brain anatomy in dyslexia were seen in comparison with both control groups, it would have suggested that reduced gray matter reflects an underlying cause of the reading deficit," Eden said. "But that's not what we observed."
Although the children with dyslexia had less gray matter than age-matched children without dyslexia, they had the same amount of gray matter as the younger children at the same reading level, according to the study, which was published online Jan. 14 in the Journal of Neuroscience.
Lead author Anthony Krafnick said this suggests that the anatomical differences reported in left-hemisphere language-processing regions of the brain appear to be a consequence of reading experience as opposed to a cause of dyslexia.
"These results have an impact on how we interpret the previous anatomical literature on dyslexia," Krafnick said in the news release. "It suggests the use of anatomical MRI would not be a suitable way to identify children with dyslexia."
