Children’s Reading Disability
Attributed To Brain Impairment
National Institutes of Health -
National Institute of Child Health and Human
Development, 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
"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
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
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,