Gene flaw causes dyslexia, researchers
boosts theory on teaching phonemes
by Quynh-Giang Tran,
Boston Globe Correspondent, 7/16/2002
Frank Rowell & the Michigan Department of Education's Office of
Special Education and Early Intervention Services' Special Education
PUBLISHED CORRECTION HAS BEEN ADDED TO THIS STORY.]
Thursday, July 18, 2002 : Correction: Because of an editing error, a
story in the Nation section on July 16
incorrectly described the results of a scientific
study of dyslexia. The study found
differences in the brains of dyslexics, but did
not find any genetic link for the differences. -
Correction submitted by Larry Geller - Thank you!
Dyslexia is caused by a genetic
flaw in the part of the brain used for reading, according to a new
study from Yale researchers that could help educators improve teaching
methods for millions of children.
Using magnetic resonance imaging, the pediatric and
neuro-researchers pinpointed the region of the brain activated by
reading and observed its disruption in children with dyslexia. The
research proved the long-held genetic theory on dyslexia, researchers
Panel says it will stop flagging SATs of disabled
Many of the dyslexic children compensated for the
disruption by using a center of the brain associated with speaking,
suggesting that sound may be key to teaching them to read.
''This is the definitive study in children that
links reading with brain function,'' said Dr. Sally Shaywitz,
professor of pediatrics at the Yale University School of Medicine and
one of the authors of the study released yesterday in the journal
Dyslexia is one of the most common learning
disorders, affecting up to 20 percent of Americans with symptoms
ranging from complete illiteracy to mixing up left and right
Children normally learn to read by recognizing
individual letters, then sounds, and finally connecting that with
conceptual meanings. Dyslexics may be as intelligent as normal
readers, but they have difficulty connecting letters with sounds, a
fundamental skill required for reading, Shaywitz said.
In the study, researchers scanned the brains of
almost 150 normal and dyslexic youths taking a reading skills test.
The test revealed that non-impaired reading is concentrated in the
occipito-temporal, lower back region of the brain, where letters and
sounds are integrated.
Dyslexics' brain activity while reading, on the
other hand, is concentrated in the frontal region, the location that
governs articulated speech. Dyslexics, in effect, read by mechanically
mouthing the words and triggering the recognition of parts of words.
Dyslexics become more proficient with reading over time but are never
cured and do not outgrow the disability.
''Now there's an urgency to identify and provide
dyslexic children with the most effective reading tools,'' Shaywitz
said. Researchers say the findings reaffirm that children should be
taught using phonemes, distinctive linguistic letter and sound units.
For example, in the word ''cat,'' the letter ''c'' is ''kuh,'' the
letter ''a'' is ''aah,'' and ''t'' is ''tuh.''
However, since the 1970s, educators have moved away
from teaching reading through sound groups and more toward learning
words in the context of sentences and pictures. Although the newer
method is useful, up to 40 percent of children need the sound and
letter approach to become fully literate, Shaywitz estimates,
including many who are not dyslexic.
''The study refines what we've known for 50 years
and may help with diagnosis,'' said J. Thomas Viall, executive
director of the International Dyslexia Association. Not being
diagnosed with dyslexia or receiving treatment has life consequences
if the student is labeled stupid or as a person having low mental
capacities, Viall said.
''Highly intelligent dyslexics can fool you,'' said
Viall, whose organization just settled a lawsuit with the Educational
Testing Service and the College Board requiring the board to stop
flagging those students who take the SAT with the special
accommodation of extra time to compensate for their learning
Humans have been speaking since the beginning of
civilization, but reading has only occurred in the last 5,000 years,
Shaywitz said. This requires the brain's circuitry to integrate
letters with sound, otherwise letters would only be squiggly lines.
The English language has 44 phonemes but more than
1,000 ways in which those letters sound, making it one of the hardest
languages to learn unless the reader was taught specifically the
pronunciation differences between words like ''mint'' and ''pint.''
Other languages, such as Spanish or Italian, have more direct
correlation between letters and sound combinations, making them easier
to learn regardless of the number of phonemes.