It has been assumed that in people with dyslexia, less gray matter in the brain is linked to reading disabilities. However, now new evidence suggests this is a consequence of poorer reading experiences and not the root cause of the disorder.
The study conducted at Georgetown University Medical Center in the Center for the Study of Learning compared a group of dyslexic children with two different control groups: a group of younger children who were matched at the same reading level as the children who had dyslexia, and an age-matched group included in most previous studies. The dyslexic groups showed less gray matter compared with a control group matched by age, consistent with previous findings, but the result was not duplicated when a control group matched by reading level was used as the comparison group with the dyslexics.
"This suggests that the anatomical differences reported in left hemisphere language processing regions 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 and it suggests the use of anatomical MRI would not be a suitable way to identify children with dyslexia," Anthony Krafnick, PhD, lead author, was quoted as saying.