abnormalities discovered in people who have trouble reading fast
ST. PAUL, Minn. – Some people who have problems reading quickly
appear to have abnormalities in the white matter of their brains,
according to research published in the December 4, 2007, issue of
Neurology®, the medical journal of the American Academy of
Neurology. Researchers say these findings provide a model to better
understand ways in which the brain may have developed differently in
people with learning disabilities.
For the study, 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 adults had dyslexia, one of the
most common learning problems in the general population, and the
other 10 participants were healthy and had no reading problems. Six
of the 10 people with PNH also underwent a specialized form of brain
The researchers found that the people with PNH had a specific
form of dyslexia that affected their ability to read words and name
things quickly. These individuals had visible disruptions in their
white matter, the part of the brain that consists mostly of fiber
tracts, or wiring, that connect together other brain regions. The
more their white matter was abnormal, the worse they 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 Bernard S.
Chang, MD, 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 says there are several limitations to the study, including
the small sample size and the fact that brain scans cannot
definitively show how the white matter fibers are actually
The study was supported by grants from the National Institutes of
Health and the Mind-Brain-Behavior program of Harvard University.
The American Academy of Neurology, an association of more than
20,000 neurologists and neuroscience professionals, is dedicated to
improving patient care through education and research. A neurologist
is a doctor with specialized training in diagnosing, treating and
managing disorders of the brain and nervous system such as epilepsy,
dystonia, migraine, Huntington’s disease, and dementia.