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Published: May 19, 2011


A learning disability of otherwise normal children characterized by an inability to read, write and spell at an appropriate level at any given age. A broad “catchall” term, dyslexia is often misused to include a variety of unrelated learning disabilities. Indeed, dyslexia has developed so many connotations that it has lost much of its connotative specificity except as a broad reference to reading problems. The National Institute of Neurological Disorders and Stroke at the National Institutes of Health defines dyslexia as “a learning disability that alters the way the brain processes written material. The effects of the disorder vary from person to person . . . the only common trait among people with dyslexia is that they read at levels significantly lower than typical people of their age and intelligence.”
The American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders calls dyslexia a developmental reading disorder whose “essential feature . . . is marked impairment in the development of word recognition skills and reading comprehension that is not explainable by mental retardation or inadequate schooling and that is not due to a visual or hearing defect or a neurological disorder.” The diagnosis is made only if this impairment significantly interferes with academic achievement or with activities of daily living that require reading skills. “Oral reading is characterized by omissions, distortions, and substitutions of words and by slow, halting reading. Reading comprehension is also affected.”
Often found in concert with other LEARNING DISABILITIES, dyslexia cannot be treated medically, but various methods of sophisticated instruction and “retraining” can teach many dyslexics to overcome the most debilitating effects on their reading, writing and spelling skills. There is no correlation between dyslexia and intelligence. I.Q.’s among dyslexics range as widely as that of nondyslexics. Dyslexia affects an estimated 15% of American children, although the range of estimates vary from 2% to 20%. Rates of dyslexia vary from region to region in the United States and from country to country.
Brain imaging studies of dyslexic children have found anomalies in the middle upper portion, or temporoparietal region, of the left half of the brain—an area that converts blocks of sound, or phonemes, to written letters and decodes their connection. Although dyslexia can be a permanent neurological malformation, there is evidence that it is developmental in some children, and, indeed, may appear and disappear. For example, only one of six in a group of 400 Connecticut children who displayed symptoms of dyslexia in the first grade continued to display those symptoms in the third grade, according to a nine-year study by pediatrician Sally E. Shaywitz, M.D., at the Yale University School of Medicine. The study also found, however, that some children who showed no symptoms of dyslexia in first grade acquired them by the time they reached third grade.
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