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Health & Wellness
Disability Research
Children's Reading Disability Attributed to Brain Impairment
Bethesda, MD, August 2, 2002 - Children who are poor readers appear to have a disruption in the part of their brain involved in reading
phonetically, according to a sophisticated brain imaging study funded by the National Institute of Child Health and Human Development (NICHD).
The study also found that children who read poorly but who do not receive any extra help or training eventually compensate for their disability by using other parts of the brain as backup systems for the impaired brain regions. Although most of these children eventually do learn to read, they never do so with the same fluency as do good readers. This is probably because the "backup" brain systems they use when reading apparently cannot process printed information as easily as can the brain systems
primarily involved in reading.
The researchers, led by Bennett Shaywitz, M.D., of the Yale
University School of Medicine, published their results in
the July Biological Psychiatry.
"This study shows us the physical basis of why some
children have difficulty reading," said Duane Alexander,
M.D., Director of the NICHD. "We are now in a position to
observe the brain changes that take place when poor readers
receive the training that allows them to become proficient
readers. In turn, this knowledge may allow us to design
even more effective therapies to help poor readers overcome
their disability."
In the study, the researchers used a technology known as
functional magnetic resonance imaging (fMRI), which
produced computer-generated images of the brain while the
children were reading. With fMRI, the team demonstrated
differences in brain images between children with dyslexia
and non-reading impaired control children. The disruption
in the brain systems for reading was evident when the
children performed phonologic tasks, that is, tasks that
required knowing the sound structure of words. Written
English is a kind of code -- letters or combinations of
letters stand for the individual sounds within words. The
reading impaired children had difficulty with tasks that
required interpretation of this code.
Dr. Shaywitz noted that the current study with children
confirmed the researchers' earlier finding with adults that
people with dyslexia have an impairment in the brain
regions involved with reading words phonetically. And like
adults with dyslexia, they use an alternate brain region as
a backup system when reading. [The earlier study is
described at:
http://www.nichd.nih.gov/new/releases/dyslexianews.cfm.]
"The study shows some very important findings," Dr.
Shaywitz said. "First it identifies neural pathways for
reading in good readers while showing a disruption of these
pathways in children who are dyslexic (Fig 1). " Second,
Dr. Shaywitz explained, the study identifies a region for
skilled reading in the the brain area known as the left
occipito-temporal region (Fig. 2). Better readers are more
likely to activate this region than are poor readers.
Third, the study shows areas of compensatory systems in the
front and the right side of the brain in dyslexic children
who are older (Fig.3).
These three images can be found at
http://www.nichd.nih.gov/new/releases/reading_disability.htm.
The researchers tested the ability of children to rhyme
nonsense words, for example, asking them: "Do [LEAT] and
[JETE] rhyme?" The children were also asked to determine
the category of real words-- "Are [CORN] and [RICE] in the
same category?" These tasks require children to use
phonology, that is, their knowledge of the sound structure
of words, which is very difficult for dyslexic readers.
Shaywitz and his collaborators used fMRI to study 144
children ranging in age from 7 to 18 years, 70 dyslexic
readers (21 girls, 49 boys) and 74 nonimpaired readers (31
girls, 43 boys ).
"Our findings show that the impairment in the brains of
children with reading disability persists into adulthood,"
said another author of the study, G. Reid Lyon, Chief of
NICHD's Child Development and Behavior Branch. "The
findings provide compelling evidence that children with
reading disabilities need to receive educational services
to help them overcome their disabilities."
Dr. Lyon added that NICHD-funded research has shown that
such services should have a firm foundation in phonological
awareness. Before most poor readers can learn to read
successfully, he said, they need to learn that spoken words
can be broken apart into smaller segments called phonemes.
Next, they usually require training in phonics- "mapping"
phonemes to the printed words on a page. Once children
have mastered these steps, they can then receive training
to help them read fluently, and to comprehend what they
read.
The NICHD is part of the National Institutes of Health, the
biomedical research arm of the federal government. The
Institute sponsors research on development, before and
after birth; maternal, child, and family health;
reproductive biology and population issues; and medical
rehabilitation. NICHD publications, as well as information
about the Institute, are available from the NICHD Web site,
http://www.nichd.nih.gov, or from the NICHD Clearinghouse,
1-800-370-2943; e-mail NICHDClearinghouse@mail.nih.gov.
Contact:
Robert Bock or Susan Marsiglia
(301) 496-5133
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