Dyslexics Have Less Gray Matter in Brain
By Ed Edelson
MONDAY, Aug. 23 (HealthDayNews) -- Brain images of people with a family history of dyslexia show significant reduction of gray matter in centers associated with language processing, Italian researchers report.
The finding, published in the Aug. 24 issue of the journal Neurology, lends credence to earlier studies that suggested intensive reading therapy activates parts of the brain needed for decoding words.
The new research "adds further support to the effectiveness of intensive reading remediation therapy to correct the reading problems associated with dyslexia," said Dr. Daniela Perani, head of research at the Institute of Neuroscience and Bioimaging in Milan and lead author of the report.
Dyslexia is a disability, usually occurring in males, in which people have trouble processing language-based information, making it difficult to learn to read, write, and spell.
Previous studies have found similar reductions in gray matter in language-associated brain centers. But the Italian research adds valuable information, said Guinevere Eden, director of the Center for the Study of Learning at Georgetown University.
"The findings are clearer in this case because the individuals came from the same family," Eden said. "When you look at people's brains, there is always some variability. The fact that these were brains of people from the same family reduced the variability."
The research included 10 people with familial dyslexia and 11 control subjects.
Another important aspect of the Italian study is that it links a number of brain centers associated with language, said Mark A. Eckert, a senior research scientist in the division of child and adolescent psychiatry at Stanford University.
The gray matter deficits in the Italian study were located in many brain areas -- top and bottom, front and back -- that are important for language functions, the researchers said.
"One problem of previous structural imaging studies is that they looked at only one brain structure at a time," Eckert said. "This [new study] shows that areas involved in both written and oral language are linked together, so you are probably talking about a network."
Eden also said earlier brain imaging studies clearly established "that there is a biological basis for dyslexia." And the finding of specific deficits in language-associated parts of the brain has led to effective therapy for dyslexia.
That therapy consists of intensive reading training sessions done day after day, with the objective of strengthening language-processing brain centers, in the same way that physical training is designed to strengthen muscles, Eckert and Eden said.
"Interventional studies have shown that the brain centers become activated after therapy," Eckert said.
An effort to develop more effective therapy is ongoing, he said, based, in part, on brain imaging. "In general, if we understand where some of the potential deficits in the brain are, we can target them," Eckert said.
Dyslexia Could Be 'Multi-Sensory' Disorder
SUNDAY, Nov. 9 (HealthDayNews) -- Dyslexia may be more than a problem of unscrambling the written word. It may stem from a glitch in how the brain processes sight and sound together, a new study suggests.
The research provides evidence that dyslexia is a "multi-sensory" disorder, as opposed to either a problem interpreting visual cues or difficulties involving language areas of the brain.
The finding could lead to a simple test for diagnosing dyslexia in children "even before they have the capacity to read," says study leader Mark Wallace, an associate professor of neurobiology and anatomy at Wake Forest University Baptist Medical Center.
Wallace reported his preliminary findings Nov. 9 in New Orleans at the annual meeting of the Society for Neuroscience, the world's largest organization of brain scientists.
Because dyslexia often goes undiagnosed, estimates of the number of children and adults in the United States who struggle with the learning disability vary greatly. Wallace says 5 percent to 10 percent of the general population is affected. Others believe the proportion could be as high as one in five Americans, or 20 percent.
For the study, 36 dyslexic adults and 29 without the disorder were tested individually in a dark room in front of a video monitor. The articipants pushed buttons to indicate which of two lights -- one a little higher, one a little lower -- appeared first.
Dyslexics and non-dyslexics alike had trouble performing that task when the lights were lit close together in time, Wallace says. But when the lights were accompanied by a hissing sound played over headphones, performance improved.
Non-dyslexics did better when the sound was played within roughly 150 milliseconds of the light -- but not longer. But the people with dyslexia showed benefits with delays as long as 350 milliseconds.
That delay in combining information from different senses goes to the heart of the problem dyslexic children experience when they are learning to read, the Wake Forest team reasons. Early reading is a multi-sensory process of matching words you see with words you hear or sound out. In dyslexics, that process is disrupted.
The study bolsters a teaching approach known as Orton-Gillingham, which relies on a combination of sight and sound to help dyslexics to read, write and spell, the researchers say.
Gordon Sherman, executive director of the Newgrange School and Educational Outreach Center in Princeton, N.J., is a proponent of that multi-sensory teaching method. He calls the Wake Forest research "a nice illustration of the importance of using both visual cues and auditory cues."
Thomas Viall, executive director of the International Dyslexia Association in Baltimore, adds that the new study is "probably good news" for parents of dyslexic children because it supports a multi-sensory education approach.
Viall says he always cautions parents to be careful when someone uses the word "cure" or promises a speedy fix for a child's dyslexia.
Wallace and his colleagues aren't promising any cures. But they do intend to perform further tests using magnetic resonance imaging to get a better handle on the mechanics of the disorder.
"The hope is that we'll be able to see what's different about the brains of dyslexics as opposed to normal-reading individuals," Wallace says. "Understanding the differences in the brain architecture may ultimately lead to a way in which we can change that architecture."
Brain Scans Being Used to Study Dyslexia
By LAURAN NEERGAARD, AP Medical Writer
WASHINGTON - Nine-year-old Patrick Price bounced up to the huge MRI machine, a powerful brain scanner disguised by drapes to resemble a kid-friendly castle. Inside, he lay nearly motionless as words and symbols flashed on a screen before his eyes.
Patrick is one of 80 Maryland youngsters with the reading disability dyslexia who are letting scientists peer inside their brains. The goal: to learn just what goes wrong when dyslexic children try to read and whether certain commercial teaching methods can make the brain rewire itself to read better.
While specially crafted instruction clearly helps dyslexic children become successful readers, there's little proof of how many of the expensive programs work, says Georgetown University neuroscientist Guinevere Eden.
"Getting information on what works, it's hard. Families go through four and five programs. They mortgage their houses," says Eden, who directs Georgetown's Center for the Study of Learning. "It's a vulnerable population."
Consumer issues aside, exactly what brain areas are activated when a dyslexic child processes words remains a question. Competing theories are driving different approaches to treatment, making it important to understand the disorder's complex neurologic underpinnings.
"It's pretty critical work," says G. Reid Lyon of the National Institute of Child Health and Human Development, a division of the National Institutes of Health (news - web sites) that is financing Eden's research.
Dyslexia is a neurologic disorder that affects 5 percent to 15 percent of Americans. They have normal intelligence but find it difficult to read, spell and master other language skills. It's often hereditary, and spotting dyslexia early is important to helping children succeed in school.
An early clue is phonological awareness, the ability to identify and manipulate sounds separately. Quick, say "Germany" without the "m." Dyslexics have a hard time, and many instruction programs aim to improve speech-sound awareness.
But, dyslexic readers also tend to be more visually oriented than normal readers, so some instruction programs are multisensory.
Eden is trying to piece together multiple brain pathways in dyslexia and to prove whether what NIH's Lyon calls their "physiologic signature" truly normalizes after different interventions at different ages.
First, Eden studied readers without dyslexia to document developmental changes required for reading that begin in early school years.
Her findings validated a theory proposed in 1925 by dyslexia pioneer Samuel Orton: Normally, youngsters depend more on the visually oriented right side of the brain at first, perhaps interpreting words as if they were pictures. As reading matures, the brain's language-linked left side grows to dominate, and visual stimulation is suppressed.
Now she's examining dyslexic brains, using a noninvasive scanner that tells what neurons are activated during reading attempts by measuring their changing oxygen levels.
Inside this "functional MRI," Patrick watches a screen flashing a mix of real words and unreadable symbols. His orders: Click one button if each screen contains a tall letter or symbol, another if it doesn't.
His brain automatically tries to read the real words, meaning Eden can trace all the pathways involved. Additional exams measure other dyslexia anomalies.
Half the children in this experiment are like Patrick, from a dyslexia-only private school near Baltimore that provides intense, specialized reading instruction. Eden hopes to recruit the other half from Baltimore public schools.
After initial brain scanning, all the kids will get, for free, $3,000 worth of a commercial dyslexia reading program — one-on-one tutoring using a phonology approach and a multisensory approach. For the study's control phase, they also get math training, to make sure simple extra attention isn't a placebo effect that temporarily boosts reading ability.
In 18 months, additional MRI testing should tell what brain-level difference the extra reading programs have made and, if they have worked, which children had been most likely to benefit.
But the youngsters learn about their own brains right away through an Eden tactic designed to boost dyslexics' sometimes flagging self-esteem. "It helps kids to know something about their brain is different, is special," she says. So she sends them home with brain pictures and stickers.
"That's my brain?" marvels Patrick, staring at images from the scanner as researchers show him his own cortex. "Wow!"
Scientists Find Cause of Dyslexia AND English is worst
Scientists say they have discovered the biological basis for dyslexia.
Research published in Science magazine suggests that parts of the brain crucial to reading are not working properly in dyslexics.
The problem exists across many nationalities, but the research found that English-speaking dyslexics suffered most, because the language is so complex.
The study has been welcomed by support groups for dyslexics.
A spokeswoman for the British Dyslexic Association said: "This endorses what we have always said, and that is that the dyslexic brain is different.
"We hope that educators will accept this and therefore identify children with dyslexia earlier and adapt their education so that they are not left behind."
The study looked at why dyslexia is more common among English or French-speakers than Italians.
The English language is made up of just 40 sounds, but these can be spelt in more than 1000 different ways, say the researchers.
In Italian, the language's 25 sounds are made up in just 33 ways.
The scientists behind the study used a body scanner to monitor brain activity in adults while they read.
They found that people with symptoms of dyslexia showed less neural activity in parts of the brain that are vital to reading (in the temporal lobe).
Comparing dyslexics in various countries, they found that English-speaking dyslexics experienced far more problems with reading and writing than the others.
And they say this is because it is so difficult in English to tell how a word is pronounced from the way it is written.
For example, there are different ways of sounding the letter combination "int".
It could sound like mint or pint.
Likewise, clove and love sound very different even though their last three letters are the same.
The same is true of French, where the same sound can be spelt in various ways.
For example: au temps sounds like autant.
It seems the Italian language is one of the most logical and simplest to master.
The researchers say in Italian, letter groups almost always represent the same unique sound from word to word.
The main scientist behind the study, Eraldo Paulescu, suggested languages like English and French could be changed to make them easier for people to read.
He said: "There is an argument for reforming complex orthographies, or writing systems, to improve literacy problems in these languages."
However, the British Dyslexic Association said this was a call which was unrealistic and unlikely to be taken up.
A spokeswoman said, in general, the study should encourage people with dyslexia.
"We hope it will lead to a greater understanding of dyslexia and that people realise that there is no reason why dyslexics should be held back from realising their full potential," she said.
Dyslexics May Miss Rhythm of Sounds, Language
Mon Jul 22, 5:37 PM ET
By Merritt McKinney
NEW YORK (Reuters Health) - In a finding that challenges conventional thinking about dyslexia, the results of a new study raise the possibility that the learning disorder is caused by difficulties in perceiving the rhythm in sounds.
Assuming that future research confirms that this problem plays a major role in causing dyslexia, it may be possible to develop tests to identify young children who are likely to develop the learning disorder, the study's lead author, Dr. Usha Goswami of University College London, UK, told Reuters Health.
People with dyslexia, despite normal intelligence and vision, have difficulty reading, writing and spelling. The exact cause is uncertain, although a person's genes are thought to play a role.
"We have known for a long time that dyslexic children have subtle spoken language problems," Goswami said. For instance, dyslexic children have a hard time with rhyming exercises and may mix up the first letters of words, changing Bob Dylan to Dob Bylan, she explained.
Researchers know that these and other difficulties predict how well a child will learn to read and spell across a variety of languages, Goswami said, but "what we haven't been able to find is the perceptual problem underlying these difficulties."
Previous studies have shown that even before children start school, their ability to "segment" syllables at the vowel--such as "sw-eet" and "str-eet"--predicts their ability to learn to read and write, even in languages that do not use an alphabet, such as Chinese.
In the new study, Goswami and her colleagues used a test that measures the ability to perceive rhythms in non-speech sounds. They compared dyslexic children with a group of children the same age who did not have reading problems. The researchers also tested a group of children who learned to read at an early age and compared them with same-aged children who had not yet learned to read.
Compared with children who did not have reading problems, dyslexic kids were less sensitive to rhythms in sound, the authors report in the advance online edition of the journal Proceedings of the National Academy of Sciences ( news - web sites). And kids who started to read early were better at picking up rhythms in sounds than children who had not yet learned to read.
Past research has focused on the troubles dyslexic children have in breaking down words into segments or "phonemes" as they learn to read. But since the new study found that dyslexic children had difficulties hearing the rhythm in sounds that were not words, the findings suggest that dyslexia may involve a more basic problem with perceiving sounds than previously thought, according to Goswami.
In children with dyslexia, "something is wrong with the perceptual mechanisms underpinning language acquisition long before reading is taught," she explained. "However, there is no simple test available to diagnose this."
If the key problem behind dyslexia turns out to be difficulty perceiving the rhythm in sounds, it may be possible to develop a test that could identify children at risk for dyslexia, Goswami said. Since children's language abilities are still forming until about age 8, such a test "would enable very early language-based intervention that could potentially be very powerful," the UK researcher said.
Goswami and her colleagues are now working to reproduce the study in 10 other countries. She said that if a problem with perceiving rhythms is indeed the basic deficit of dyslexia, then it should be related to reading and spelling abilities in other languages, at least in those that have consonant-vowel syllable structures.
SOURCE: Proceedings of the National Academy of Sciences 2002;10.1073/pnas.162368599.
Reading Help May Alter Brain Activity in Dyslexia
Tue Apr 30, 1:14 PM ET
By Merritt McKinney
NEW YORK (Reuters Health) - In a finding that raises hopes about the effective treatment of dyslexia, the results of a small study show that intensive reading instruction may reverse the abnormal brain activity that occurs in children with the learning disability.
The research "provides a more optimistic outlook for the prognosis of dyslexia," according to a report on the findings in the April 23rd issue of the journal Neurology.
"It appears that although dyslexia has a demonstrable neurologic basis, it is not a neurologic disease," states a team of researchers led by Dr. Panagiotis G. Simos, of the University of Texas-Houston Health Science Center.
"Rather, word reading difficulties most likely represent variations in normal development that can be reversed by means of reading intervention," the authors assert. People with dyslexia, despite normal intelligence and vision, have difficulty reading, writing and spelling. The exact cause of the learning disorder is uncertain, although a person's genes are thought to play a role.
The consensus among researchers is that the brain network involved in reading words is abnormal in people with dyslexia, Simos told Reuters Health. Precisely how the network goes awry is not understood, however, he added.
In the present study, the researchers studied eight children, aged 7 to 17, who had severe reading difficulties. At the start of the study, the children underwent a brain scan called magnetic source imaging (MSI) that measured brain activity while reading. The children underwent MSI a second time after completing an 8-week remedial reading course that included 1 to 2 hours of one-on-one instruction each day. A set of similarly aged children without dyslexia also underwent MSI at the start and end of the study, although they did not receive remedial instruction.
The scan was used to measure activity in a brain region called the left superior temporal gyrus, or left STGp. In people without dyslexia, this part of the brain becomes more active during reading. Dyslexic people, however, experience little or no activity in this part of the brain during reading.
As expected, the brain scans performed before the reading program detected little or no left STGp activity in dyslexic children. After the reading program, however, activity in this part of the brain jumped in the dyslexic children. Brain activity stayed the same in children who did not have dyslexia.
"Our findings show that successful completion of an intensive remediation program in reading is associated with dramatic changes in brain activation profiles in children with very severe reading difficulties," Simos and colleagues conclude.
It is possible, according to the researchers, that young children end up developing learning difficulties because their disorder is not identified soon enough or they never receive appropriate training to teach the brain to recognize words properly.
The kind of instruction a child receives could play an important role in the development of the brain network needed for reading, Simos noted. His research team is continuing to study brain circuits in dyslexic and non-dyslexic children to get a better idea of the normal course of development.
The investigators are also examining whether a school-based reading curriculum beginning in first grade can prevent the development of abnormal brain circuitry that occurs in older children with dyslexia. Simos and colleagues also hope to find out whether there is a certain time in a child's development when such programs are most effective.
According to Dr. Peter B. Rosenberger of Massachusetts General Hospital in Boston, however, it is too early to conclude that an intensive remedial program can reverse dyslexia.
The issue is whether increased brain activity in a certain region is related to reading problems or is instead merely a reflection that the person is doing something differently, Rosenberger, who is the co-author of an accompanying editorial, told Reuters Health.
"For example, the light on the switchboard doesn't cause the telephone call," he said. "It is merely a signal that the call is taking place."
In the editorial, Rosenberger and co-author Dr. David A. Rottenberg, of the University of Minnesota in Minneapolis, also point out that six of the children began taking stimulant medication to treat attention-deficit disorder after the first scan.
SOURCE: Neurology 2002;58:1189-1190, 1203-1213.
Prevalence and clinical characteristics of dyslexia in primary school students.
Roongpraiwan R, Ruangdaraganon N, Visudhiphan P, Santikul K.
Department of Pediatrics, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand.
BACKGROUND: Dyslexia is the most common subtype of learning disabilities with a prevalence ranging from 5-10 per cent. The central difficulty in dyslexia is the phonological awareness deficit. The authors have developed a screening test to assess the reading ability of Thai primary school students. OBJECTIVE: 1. To study the prevalence of dyslexia in first to sixth grade students at Wat Samiannaree School. 2. To study the clinical characteristics such as sex, neurological signs, verbal intelligence and comorbid attention deficit hyperactive disorder (ADHD) of the dyslexia group. METHOD: A total of 486 first to sixth grade students were administered "Raven's progressive matrices test" for estimation of intellectual functioning. Those who scored below the fifth percentile were labeled as mental retardation and excluded from the study. The students' reading ability was evaluated by 3 steps; first by classroom teachers using some items of the screening test, second by the researchers examining some more items individually, and third by the special educator assessing more details in reading and phonology. The students who had a reading ability two-grade levels below their actual grades and impairment in phonology were diagnosed with dyslexia. RESULTS: The prevalence of dyslexia and probable dyslexia were found to be 6.3 per cent and 12.6 per cent, respectively. The male to female ratio of dyslexia was 3.4:1. The dyslexia group had significantly lower Thai language scores than those of the normal group (p < 0.05). All of the dyslexia group had a normal grossly neurological examination but 90 per cent showed positive soft neurological signs. Mean verbal intellectual quotient score in the dyslexia group assessed by using Wechsler Intelligence Scales for Children--Revised was 76 +/- 7. The comorbid ADHD was 8.7 per cent in the dyslexia group. CONCLUSION: Dyslexia was a common problem among primary school students in this study. Further studies in a larger population and different socioeconomic statuses are required to determine the prevalence of dyslexia in the general population. The authors suggest evaluating the reading ability carefully by using a test that can detect phonological awareness deficit in all children who have learning problems.
PMID: 12549782 [PubMed - in process]