A new way to evaluate dyslexia

Neuroscientists show that brain scans can predict whether children’s reading ability will improve.


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Brain scans may be able to predict which children with dyslexia are likely to improve their reading skills over time, according to a new study led by MIT and Stanford researchers.

Some 5 to 17 percent of U.S. children suffer from dyslexia, a learning disorder that makes it difficult to read. Many dyslexic children are able to make substantial improvements in reading ability, but how they do so is not well-understood, and standardized reading tests cannot predict which children are likely to become stronger readers.

If the findings are confirmed in larger studies, brain scans could be used as a prognostic tool to predict reading improvement in dyslexic children. They could also help scientists and educators develop new teaching methods that take advantage of the brain pathways that dyslexic children appear to use to compensate for their disability, says John Gabrieli, MIT professor of brain and cognitive sciences. Such strategies may be able to help dyslexic children regardless of which brain patterns they show.

Gabrieli, who is also a member of MIT’s McGovern Institute for Brain Research, is a senior author of the paper on the work appearing in the Proceedings of the National Academy of Sciences the week of Dec. 20. The lead author is Fumiko Hoeft of Stanford University School of Medicine.

Trouble with words

Experts disagree on a precise definition of dyslexia, with the consensus view being that children with dyslexia have difficulty learning to read, despite normal intelligence. Preschool-age children who will go on to become dyslexic often exhibit weakness in analyzing the sounds of language, such as whether or not words rhyme. As they get older, dyslexic children have difficulty associating sounds with letters, and decoding written words. However, around 25 to 50 percent of dyslexic children eventually develop compensatory strategies that enable them to read well enough to do their schoolwork.

Over the past decade, a type of brain scan known as functional magnetic resonance imaging (fMRI) has allowed researchers to learn a great deal about the brain regions that may be involved in dyslexia. However, so far this has not led to any direct benefits for patients, says Gabrieli. “I got interested in how brain imaging could do something that would get you closer to helping people,” he says.

In the new paper, Gabrieli and colleagues studied 25 dyslexic children, all ranging from 11 to 14 years old, as well as 20 normal readers of the same ages. Each subject’s brain was imaged as he or she decided whether pairs of words rhymed.

Two and a half years later, the researchers examined the reading ability of the same dyslexic children. They found that the children who improved the most were those who had the most activity in the right prefrontal cortex and also the strongest white-matter connections in the right prefrontal cortex during the first test (white matter consists of nerve bundles that carry messages from one area to another). The combination of these two brain measures was an even stronger predictor than either one alone. These brain regions were unrelated to reading gains in typical children.

Dyslexic children may be using the right prefrontal cortex, which is believed to be involved in visual memory, to memorize words, says Gabrieli. In contrast, normal readers use the right prefrontal cortex less and less as they move from memorizing words to figuring out words “on the fly” by translating letters into sounds. That task requires language-processing areas located in the left hemisphere.

The role of the extra-strong organization in the right-hemisphere white matter is still a mystery, says Gabrieli. In the left prefrontal cortex, white matter connects language areas. However, it’s not known what the corresponding white matter in the right prefrontal cortex does, or how activity in those areas would help dyslexic children read, says Gabrieli.

Alternative strategies

The new findings suggest that dyslexic children who overcome their reading difficulties somehow bypass brain regions normally used for reading, says Gabrieli. “It seems like they’re better off using a completely different strategy,” he says.

That could prompt educators to develop new ways of teaching dyslexic students, focusing on the appropriate brain regions, says Gabrieli. “Current interventions try to get kids to use typical approaches to reading. But you may be better off promoting a different approach to reading altogether in older children,” he says. One possibility would be to emphasize a more visual approach, similar to “speed reading,” as opposed to teaching dyslexic children to translate letters into sounds.

“Those children who did not improve might have the most to gain if instructions were developed that took into account alternative reading strategies, instead of trying to get struggling readers to read like good readers,” says Gabrieli. “Those who improved might have discovered on their own what works for them, and those who failed to improve might most be in need of explicit instruction and support to try a different strategy.”

Manuel Casanova, professor of psychiatry at the University of Louisville, says the study’s most important contribution is revealing that the behavioral and intelligence measures commonly used to evaluate a dyslexic child’s chances of improvement — such as IQ tests and standardized reading tests — are not reliable. “The conventional wisdom until now has been behavioral measurements,” says Casanova. “I am blown away by the fact that IQ is not predictive of the ability to improve.”

However, he points out that evaluating children at a younger age, when they are more likely to be able to improve, would be more useful to doctors and educators.

Gabrieli plans to repeat his fMRI study in younger children with dyslexia, and he is also studying the prognostic ability of fMRI in other brain disorders. He is optimistic that fMRI has potential to help doctors select the best treatment for individual patients, not just for dyslexics but those who suffer from many other brain disorders such as depression, anxiety and schizophrenia.


Topics: McGovern Institute, Neuroscience

Comments

When I was in junior high school, a friend said that he was unable to learn to read from school, but had learn to read from comic books. He did not sound out word but rather recognized them as a whole. He read about 600 words per minute with good comprehension. In addition to visual recognition, I think contextual cues should be practiced: One's understanding is likely to be correct if it makes sense. And if it is not necessary to teach by analysis and raising the skills to a conscious level then don't. On the other hand I never was diagnosed as dyslexic, although I was so ambidextrous in grade school that I printed the first half of words with one hand and the last half with the other hand to avoid writers cramp. I learned to read by sounding out words, and became quite good at it, but this cost in speed. The many exceptions, became like speed bumps, and more and more conscious. So to this day I spell many words incorrectly, knowing that I am doing so, and then correct them afterward habitually, or else have to spend time to feel for which spelling actually correct. The more one thinks about it the more both ways become familiar. Similarly, my learning to write upside-down, backward, mirror, and/or with my other hand, seemed to have negative effects on reading/writing speed. I am very quick at recognizing and analyzing patterns, and rotating them mentally, but poor at memorizing, and speed skills such as typing. I think developing the ability to analyse and correct in reading is for this reason the wrong approach, but I don't have experience in teaching dyslexics. Another interesting observation is the importance of environment. I have been living in Thailand for many years among people, who because of the selection of sounds in their native Thai Language cannot hear, and do not pronounce consonant clusters at the ends of words, and also mix L and R sounds. Years ago, I started to notice, that as I typed, I would frequently make typos of the same type: missing s or ed, switched r and l. These are not normal errors for a native English speaker. They must derive from the reliance on acoustical cues for spelling, and on the modification of these queues through my adapting my perception of speech sounds in order to optimize the ability to decode the English of the people around me. Perhaps these experiences can help stimulate further investigations that can help in training some types of dyslexics.
Another small step in understanding dyslexia by fMRI. Understanding dyslexia is important but the information gained about individuals by fMRI is crude compared to oral and written testing by professionals. Reports like this give the impression that at some future date dyslexics will be able to be scanned and receive information about individualized interventions. That is unlikely. I applaud promoting, by implication, the concept that all dyslexics are not alike and different interventions are required for different dyslexics. "Experts disagree on a precise definition of dyslexia" I can not state strongly enough that lacking a precise definition makes discussions about dyslexia difficult. I suggest that dyslexia can be best defined as a syndrome and this study makes another step in that direction. In the end that may be the major importance of the data from this study. I believe all the fMRI studies to date taken together indicate dyslexia is a syndrome. I agree "However, so far this (fMRI brain research) has not led to any direct benefits for patients." This study has not changed the validity of that statement. By the way, I would think that the impression from the article that some dyslexics are never going to improve their reading skills is not what was really meant. That is basically what the article said. The ability to predict which dyslexic will improve certainty implies that others will not. I wonder if a better conclusion is that without any intervention some dyslexics don't improve while others find compensatory methods. I hope to read the actual study someday rather than an article about the study.
Would one advise treating this condition or offering the option to treat? Maybe treatment will be best received by those with the greatest ability for fluid learning? In the November 4th edition of Current Biology a study entitled, ‘Modulating neuronal activity produces specific and long lasting changes in numerical competence,’ researchers demonstrate how electrical stimuli to one hemisphere of the brain helps improve math skills. Might this technology also help in language learning skills? With some more precision will we be able to direct the signals or the ability to send signals to specific neurons and/or synapses? Has anyone tried utilizing an eye patch, or glasses to help in the development of one side of the brain while reading? Is it possible people are not using one hemisphere in reading do to a lack of blood flow or a clot, which could prevent nutrients needed for signal transmissions? Has anyone looked into utilizing an ultrasound to noninvasively determine if this is the case? And if this is the case, then might the ultrasound be able to determine the density of the blockage given it is not structural and help us to understand a resonant frequency to which we can program the sound to aid in the passage and unlocking of the blockage? Have we looked into aspirin in the case saprophytes are causing the blockage? If we determine, during the course of consultation, not to treat, then I think it is important we accept people with the condition. Moreover, I think we ought to allow them hone this talent by offer teaching methods which specifically appeal to this group. Different thinking styles will more likely than not benefit society at large, a monoculture of thinking styles would, I think, weaken a diverse society. Some employers might have a specific need for this type of thinking ability, say the advertising industry. What are we doing to aid employers in finding this talent and aid these talent individuals to finding employment. I think it is often the case some of our talents are seen as burdensome rather than a gift. For those who view dyslexia in this manner, maybe it is best to treat the condition. While for others who enjoy the utilization of one side of the brain over the other, maybe it is best to teach in the style which allows them to learn the most either by offering dyslexia specific classes/schools or encouraging teachers to teach for the multitude of learning styles. After the completion of the level of education sought, maybe schools can educate employers about the benefits of including a person with dyslexia onto the team, but not in those terms as dyslexia might harbor negative connotations. Thanks for this article and the insight.
I have the ability to touch any part of a persons head and tell how that part of the brain is used, "worry, logic, passive, etc'" I have learned that during meditation whenever I find an area inside the brain that is active I can trace it back to a tiny area on top of the head. I have used this ability on two autistics, one's face totally changed and the other one fell asleep as if over stimulated. I teach a unique form of conscious meditation that teaches people to active neuropathways from inside the brain.
I've just done a blog about this paper, explaining the methods for a general readership, and adding some comments of my own http://deevybee.blogspot.com/2010/12/neuroprognosis-in-dyslexia.html
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