Brain scans of adolescents with dyslexia can be used to
predict -- with up to 90 percent accuracy -- future reading gains.
New research shows that analyses of brain images are
significantly more accurate in driving predictions than standardized reading
tests or any other measures of children's behavior.
The finding raises the possibility that a test one day could
be developed to predict which individuals with dyslexia would most likely
benefit from specific treatments. The research is reported in the Proceedings
of the National Academy of Science.
"This approach opens up a new vantage point on the
question of how children with dyslexia differ from one another in ways that
translate into meaningful differences two to three years down the line,"
says Bruce McCandliss, a psychology professor at Vanderbilt University and a
co-author of the report."Such insights may be crucial for new educational
research on how to best meet the individual needs of struggling readers.
"This study takes an important step toward realizing the
potential benefits of combining neuroscience and education research by showing
how brain scanning measures are sensitive to individual differences that
predict educationally relevant outcomes," he says.
Brain imaging
The researchers used two types of brain imaging technology
to conduct their study. The first, functional magnetic resonance imaging (fMRI)
depicts oxygen use by brain areas involved in a particular task or activity.
The second, diffusion tensor magnetic resonance imaging (DTI), maps white
matter tracts that are the brain's wiring, revealing connections between brain
areas.
The 45 children who took part in the study ranged in age
from 11 to 14 years old. Each child first took a battery of tests to determine
his reading abilities. Based on these tests, the researchers classified 25
children as having dyslexia, which means that they exhibited significant
difficulty learning to read despite having typical intelligence, vision, and
hearing and access to typical reading instruction.
During the fMRI scan, the youths were shown pairs of printed
words and asked to identify pairs that rhymed, even though they might be
spelled differently. The researchers investigated activity patterns in a brain
area on the right side of the head, near the temple, known as the right
inferior frontal gyrus, noting that some of the children with dyslexia
activated this area much more than others.
DTI scans of these same children revealed stronger
connections in the right superior longitudinal fasciculus, a network of brain
fibers linking the front and rear of brain.
When the researchers administered the reading
test battery to the youths two and a-half years later, they found the 13
youths showing the stronger activation pattern in the right inferior frontal
gyrus were much more likely to have compensated for their reading difficulty
than were the remaining 12 youths with dyslexia.
Accuracy rates
When they combined the most common forms of data analysis
across the fMRI and DTI scans, they were able to predict the youths' outcomes
years later with 72 percent accuracy.
The researchers then adapted algorithms used in artificial
intelligence research to refine the brain activity data to create models that
would predict the children's later progress. Using this relatively new
technique, the researchers could use the brain scanning data collected at the
beginning of the study to predict with over 90 percent accuracy which children
would go on to improve their reading skills two and a half years later.
In contrast, the battery of standardized, paper-and-pencil
tests typically used by reading specialists did not aid in predicting which of
the children with dyslexia would go on to improve their reading ability years
later.
Treatment indicator
"Our findings add to a body of studies looking at a wide
range of conditions that suggest brain imaging can help determine when a
treatment is likely to be effective or which patients are most susceptible to
risks," says study leader Fumiko Hoeft, associate director of neuroimaging
applications at Stanford University.
The largest improvement was seen in reading comprehension,
says Hoeft, which is the ultimate goal of reading. The youths showed less
improvement in other reading-related skills such as phonological awareness.
Typically developing readers tend to develop phonemic awareness skills before
developing fluency and comprehension skills.
Hoeft suggests the finding that youths with dyslexia recruited right brain frontal regions to compensate for their reading difficulties, rather than regions in the left side of their brains -- as typical readers do -- may have something to do with this.
