Ability to Catch Dyslexia Early May Help Stem Its Effects


by Elizabeth Norton Lasley

September, 2009

New educational approaches and advances in brain-based research are making it possible to detect dyslexia even in children too young to read. Though it is not a cure, stepping in early with targeted intervention could prevent reading problems from derailing a child’s education.

“There has been a giant change in the last 15 years in the way dyslexia is understood,” says John Gabrieli, head of the McGovern Institute for Brain Research at the Massachusetts Institute of Technology. “We’ve moved from thinking of dyslexia as a purely visual ‘reading’ disorder to knowing it’s a phonological difficulty in perceiving the sounds that make up words.”

“People with dyslexia have trouble pulling apart the words they hear,” says Sally Shaywitz, co-director of the Yale Center for Dyslexia and Creativity, at Yale University. “The word ‘cat,’ for instance, has only one syllable, but it has three individual sounds—the c, the a, and the t.”

Difficulty subdividing words shows up as a reading disorder, she explains, because reading involves “mapping” the images of written letters onto sounds the reader already knows. If someone doesn’t hear a spoken word as a group of component sounds, then the written word won’t make sense.

“In a world without reading, these problems might never be relevant,” Gabrieli says.

In a society becoming increasingly text-based, however, dyslexia can have serious consequences. A poor reader in first grade has a 90 percent probability of reading poorly in fourth grade and a 75 percent probability of reading poorly in high school. As children with dyslexia labor to read, the obstacles they face can make them reluctant to keep trying, which can set them back further.

Research Suggests Effects and Causes

In 1983, Shaywitz and her husband, Bennett, also of Yale, began the Connecticut Longitudinal Study of dyslexia. Of the 445 children enrolled in the study and monitored since it began, almost 90 percent continue to participate.

The Connecticut Longitudinal Study revealed that reading difficulties occur along a continuum, and children who did not meet diagnostic criteria for dyslexia might still benefit from extra help. The study also found that 20 percent of children were reading below their grade level, yet only one-third of these children were receiving assistance. Moreover, reading problems were assessed in third grade, already past the ideal time for intervening. Finally, the study found that dyslexia is persistent, not just a temporary lag in reading development.

Brain-imaging studies conducted throughout the 1990s further revealed that dyslexia carries a unique neural signature. Normally, reading involves three key brain areas, all in the left hemisphere. The relatively well-known Broca’s area, toward the front of the brain, and a second area toward the back support slow, step-by-step analysis and “pulling apart” of words. Skilled readers activate a third area, toward the bottom of the brain (near the depressions beneath the ears). Called the occipito-temporal region or, increasingly, the word-form area, this region does not analyze a word but reacts, almost instantaneously, to the whole word as a pattern.

The best readers show the most activation of the word form region, Shaywitz says. Readers with dyslexia, on the other hand, show reduced activity in the word-form area, whereas the forward areas, involved in word analysis, are more strongly activated than they are in skilled readers. People with dyslexia often laboriously mutter words they are attempting to read—suggesting that without a well-functioning word-form area, readers have to work much harder.

Early Detection and Intervention

As dyslexia is not a developmental lag but a different mode of brain organization, it cannot be prevented or cured and does not go away over time, Shaywitz says. Recent research, however, suggests that early intervention can help forestall, or at least lessen, some of the reading difficulties that result.

Gabrieli is intrigued by studies that employ an electroencephalogram, or EEG, to record changes in brain activity (called event-related potentials) in response to language. Using this approach, several groups have found that newborns from families with dyslexia show differences in response to language sounds within hours or days of birth.

A recent study of kindergarten-age children suggests that measuring this type of electrical activity may predict reading difficulty more accurately than behavioral measures alone. Reporting online in the May 7 Biological Psychiatry, Daniel Brandeis and colleagues at the University of Zurich showed a correlation between altered electrical activity when the children were in kindgergarten and their reading performance five years later. The authors concluded that brain-based measures could complement behavioral methods of dyslexia prediction, especially in children with a family history of the condition.

Gabrieli and Shaywitz each have published studies showing that early intervention can help correct anomalies in brain activity in children with dyslexia. In the May 1, 2004, Biological Psychiatry, the Shaywitzes and colleagues reported that a rigorously tested “evidence-based” intervention in children ages 6 to 9 led to significant gains in reading accuracy and increased activation in key brain areas for reading. Follow-up imaging a year after the experimental period ended showed that these improvements persisted.

In the August 2008 Neurologia, Gabrieli and colleagues reported similar results when they tested struggling readers in fifth grade after 100 hours of intensive remedial reading. This intervention also led to dramatic changes in brain activity that were still evident in a follow-up a year later. The changes, however, appeared in different regions than those the Shaywitzes and others pinpointed, perhaps because the children Gabrieli’s team studied were older.

Gabrieli envisions routine testing in preschool or kindergarten that would start with asking children to pick words that rhyme or that begin with the same sound. Children who had trouble with these tests could then have a quick event-related-potential test to see if they might be good candidates for treatment.

Older children could be asked to spell nonsense words. This approach, Gabrieli says, is a good test for a group that’s difficult to identify: dyslexic children who are especially bright.

“These kids simply memorize lots and lots of words, and in the early years they don’t realize how hard they’re working—they just expect reading to be difficult. But then, around fourth grade, when everything—even most of the math—is text, text, text, they have too many words coming at them to keep up with. By that time, intervention is usually less effective,” Gabrieli says.

Parents can spot potential signs of trouble even earlier than preschool or kindergarten, Shaywitz says. Late speech (not saying first words until after 15 months of age and not speaking in phrases until after age 2) may indicate a future reading disability. The biggest indicator, she says, is the inability to appreciate rhymes. “If a child doesn’t seem to ‘get’ the funny rhymes in a Dr. Seuss book, this may be a first sign of a reading disorder,” she says.

Carefully studied evidence-based interventions that emphasize phonologic processing and intensive time with well-trained teachers can identify children likely to have reading problems and greatly improve their reading ability, Shaywitz says. She cautions, though, that these interventions improve only reading accuracy. The improvement of reading fluency—governed by activity in the brain’s word-form region, remains elusive and may involve additional approaches, including pharmacological treatment.

“It’s important to remember, especially for parents struggling to help their children, that dyslexia is something you are born with,” Shaywitz says.