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Family Solutions for Dyslexia, LLC |
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What is Dyslexia?
The International Dyslexia Association adopted the following definition of dyslexia in November, 2002. It was revised by The National Institutes of Health January 1, 2003: Dyslexia is a specific learning disability that is neurological in origin. It is characterized by difficulties with accurate and/or fluent word recognition, and by poor spelling and decoding abilities. These difficulties typically result from a deficit in the phonological component of language that is often unexpected in relation to other cognitive abilities and the provision of effective classroom instruction. Secondary consequences may include problems in reading comprehension and reduced reading experience that can impede growth of vocabulary and background knowledge. Scientifically speaking, dyslexia affects a specific component of the brain's language system; the phonologic module. The phonologic module is the functional part of the brain where spoken sounds are put together to form words, and where words are broken down into their sounds. The ability to do these sound tasks is referred to as phonologic processing - processing the distinct sounds of language. Phonologic processing is at the very crux of reading disability. Dr. Sally Shaywitz, in her book Overcoming Dyslexia, states that, " Before a word can be identified, understood, stored in memory, or retrieved from it, it must first be broken down into phonemes [individual sounds] by the neural circuitry of the [phonologic module] (2003, pgs. 41-42)." Language is a code, and the only code recognized by the language systems of the brain is a phonologic code. Therefore, if children can not break words into their phonemes (individual sounds), they can not be processed by the language systems of the brain and stored for later recognition and retrieval. In dyslexic children, phonemes are less well developed. For this reason, when dyslexic children speak, they may select a similar sound or word rather than the one they wanted. They might order the phonemes incorrectly resulting in pasghetti for spaghetti. These same children will say drapes for crepes confusing words that sound alike. This confusion does not reflect their intelligence or understanding of the words. They know what both drapes and crepes are, but the similar sounding word was retrieved causing a phonologic slip, not a comprehension slip. Dyslexia can also be characterized by the inability to revisualize a whole word. Dyslexics can have difficulty with automatic recall of visual images (and words). This difficulty appears to be linked to the word form area in the back left side of the brain where whole words are stored along with how they sound and what they mean. The dyslexic may still have a good grasp of phonetic concepts and can spell words which may be long but are phonetically regular. They will have difficulty with irregular, nonphonetic words (generally referred to as sight words) such as want, what, the, does, or was, to name a few. This is because these children can apply sound-symbol strategies and store words by sounding them out. They have trouble storing words that are irregularly spelled (such as does or the) because irregular words can't be sounded out and have to be memorized by sight. For this reason, this type of dyslexic child tries to sound out the same irregular word over and over on a page as if they are seeing it again for the first time. These same children can spell or read really big words if they are phonetically regular. Dyslexia can also be a combination of all of the above difficulties which can also cause weak visuo-motor skills.
Dyslexia is considered to be a chronic condition that is not a temporary lag in reading development that will go away if you just give the child more time. Dyslexia is a different type of brain organization that causes difficulty with language processing. Dyslexia comes in different degrees of severity from mild, to moderate, to severe, to profound. The brain becomes organized in a different way during fetal life as neurons are directed to areas of the brain by messages they receive from chromosomes. For this reason, people with dyslexia have unusual wiring. Neurons are found in unusual places in the brain and they are not neatly ordered as in non-dyslexic brains. A study at the Universtiy of Washington concluded that dyslexics were using 4.6 times as much area of the brain to do the same language tasks as non-dyslexics. They reported that most of the brain activity that was measured took place in the front left areas of the brain that process expressive language. Good readers rely on the back areas on the left side of the brain. Scientists used to think that the dyslexic brain had a larger right hemisphere even though the left hemisphere is supposed to be about 10% larger than the right. In the normal developing brain, the left hemisphere is larger resulting in an asymmetrical brain. When both hemispheres are the same size, the brain is symmetrical and doesn't have the larger left hemisphere to dominate the language functions. More recently, scientists think that the left hemisphere actually didn't get larger than the right hemisphere and is causing the symmetry of the hemispheres. This lack of hemisphere dominance causes processing difficulties for dyslexic individuals. | ||||||||||||||||||||||||||||||||
How do you get dyslexia? What scientists are now calling developmental dyslexia is biologically based. It is inherited, so it is genetic. Some of the research on genetics is receiving a lot of attention. For example, in 2001, scientists found a dominant gene on chromosome #3 that affected phonological awareness, rapid naming and short-term memory. A defect of this gene was present in families who shared the same symtoms of dyslexia. In 2004, researchers determined that a gene on the short arm of chromosome #6 was also responsible for dyslexia. This gene is also dominant, making dyslexia highly heritable. In 2005 researchers located two genes that play a role in the necessary migration of neurons as the fetal brain develops. One gene is called the DCDC2. This gene supports the circuitry that underlies reading. When it is flawed it causes neurons to travel shorter distances. This undercuts early brain development. The other gene is called Robo1. It is a developmental gene that develops connections between the brain's left and right hemisphere. When this gene's activity is reduced, the finer connections between the two hemispheres, called dendrites, are reduced in the brain areas that are involved in reading. Although the correct signals still process between hemispheres, they don't process as rapidly. This is highly significant since many experts in dyslexia believe that reading problems stem from the inability to process the fast sounds in spoken words. Is dyslexia curable? How many people have dyslexia? A longitudinal study was conducted at Yale University on 445 children by doctors Bennett Shaywitz and Sally Shaywitz. Titled the Connecticut Longitudinal Study, it indicated that reading disability affects approximately one in five children. This means that in a classroom of 20 children, four of them suffer from some degree of reading disability. Some researchers estimate that dyslexia affects five to twenty percent of our population. This disability has been reported from all over the world, occuring in languages from Germany, China, Japan, Africa, Italy, Sri Lanka, Sweden, Israel, Thailand, England and Argentina. Scientists, diplomats and CEO's alike have all reported difficulties with reading. Dr. Sally Shaywitz states, "Dyslexia clearly knows no boundaries, neither geographic nor ethnic nor intellectual (2003, pg. 31)." Why do more boys than girls seem to have trouble reading? Dr. Shaywitz noted that dyslexia affects boys and girls equally. In past years we have always had many more boys than girls qualify for reading support. Dr. Shaywitz noted that this is because girls with reading disability are not as readily identified. Girls have to struggle for a longer time in school before they become severe enough to be identified as having a problem. Therefore, if you feel that your daughter is struggling with reading, the Warning Signs of Dyslexia apply to her, too. There are no gender boundaries with dyslexia. More recently, better assessments that measure a child's phonological processing abilities are starting to identify many more students who struggle, whether male or female. For this reason, more and more girls are qualifying for reading support under the newer Response to Intervention model used across the nation. None-the-less, there are still more boys identified than girls. Dyslexia is not due to vision problems - it's a language problem! Dyslexia is not a visual problem. Children with dyslexia have normal vision. You may have noted that the IDA mentioned in their definition of dyslexia that the disability is not due to poor vision. Poor visual accuity may coexist with dyslexia, but the wiring, or lack thereof, in the phonologic/language processing areas of the brain causes dyslexia, not poor eye sight. Dyslexic students can wear glasses and still demonstrate the same phonological difficulties they had before obtaning glasses. For this reason, eye training is not considered to be a solution for dyslexia. Some families have reported that eye training (vision exercises) did allow their child to track print easier and not complain about eye strain or tired eyes. This made reading less of a strain for them and therefore contributed to a new found willingness to read for pleasure. Note that these students do still struggle with the phonological components of langugage until they receive proper interventions for their poor decoding and spelling skills. Dyslexics don't see things backwards. They have trouble with directionality - they are left, right confused. For example, with the letters b - d, dyslexics can't remember which one points left because they confuse left from right. Therefore, they have difficulty naming the letters. This problem is considered to be a linguistic and/or memory one, not a visual one. Most families receive help for their dyslexic child through individual tutoring by a qualified tutor. A qualified tutor is one that is trained in the Orton-Gillingham system or an adaptation of that program. Past president Margaret Byrd Rawson of the International Dyslexia Association said it best: "Dyslexic students need a different approach to learning language from that employed in most classrooms. . . They have to have lots of practice in having their writing hands, eyes, ears, and voices working together for the conscious organization and retention of their learning (quoted in Samuel T. Orton and his Legacy, 1999, pg. 142)." For more information about tutoring click the Tutoring link at the top of the page.
If you feel that your child may have dyslexia, you should first review the Warning Signs of Dyslexia link at the top of the page. Then, refer to the Diagnosing Dyslexia link at the top of the page. The brain images on this and other pages are courtesy of 3DScience.com.
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