A new study has revealed that some people who have problems reading quickly may be having abnormalities in the white matter of their brains, which consists mostly of fibre tracts or wiring that connect together other brain regions.
The researchers behind the study, published in the medical journal Neurology, say that their findings provide a model to better understand ways in which the brain may have developed differently in people with learning disabilities.
During the study, the researchers tested the reading and cognitive abilities of 30 adults, 10 of whom had periventricular nodular heterotopia (PNH), a rare genetic brain disease that causes seizures and reading disabilities.
Ten of the subjects had dyslexia, one of the most common learning problems in the general population, while the remaining 10 participants were healthy and had no reading problems.
Six of the 10 people with PNH also underwent a specialized form of brain scan.
It was observed that people with PNH had a specific form of dyslexia that affected their ability to read words and name things quickly. Such individuals were found to have visible disruptions in their white matter.
According to the researchers, the more the white matter was abnormal, the worse the subjects performed on rapid reading tests.
"Our findings suggest that white matter integrity plays a critical role in reading fluency and that defects in white matter serve as the structural basis for the type of dyslexia we see in this brain malformation," said the study's lead author Dr. Bernard S. Chang, with Harvard Medical School in Boston, and member of the American Academy of Neurology.
"Our work highlights the importance of studying white matter structure in order to understand cognitive problems and learning disabilities more fully," Chang added.
The author, however, accepted that there were several limitations to the study, including the small sample size, and the fact that brain scans could not definitively show how the white matter fibres are actually connected.