Dyslexia << dihs LEHK see uh >> is the most common type of learning disability. It is characterized by difficulties recognizing and making sense of written words and sentences. It is also characterized by poor spelling.
Health professionals may diagnose dyslexia after careful evaluation of a child’s reading skills and other cognitive (mental) abilities. Such professionals include school or clinical psychologists and speech pathologists. The term dyslexia is usually used by clinicians. Educators tend to use the term reading disability.
The difficulties that characterize dyslexia result from a deficiency in the phonological component of language understanding. The phonological component consists of rules that tell how to pronounce words and sentences. The deficiency originates in the brain and nervous system. It exists independent of other cognitive abilities, which are usually normal, and despite classroom reading instruction. Other complications of dyslexia may include problems in reading comprehension and reduced experience with reading. Reduced reading experience can limit a child’s vocabulary growth and background knowledge.
Scientists do not know the exact cause of dyslexia. But they know that genes play a role in the condition because the disability runs in families. Children of a dyslexic parent are more likely have the disability themselves.
Neuroscientists have studied dyslexia using modern imaging technology, such as magnetic resonance imaging (MRI). They have found differences in brain anatomy and brain function between people who have dyslexia and those who do not. Studies suggest that there are differences in the left side and back portions of the brain between dyslexic and nondyslexic individuals. The affected areas of the brain are not only those that involve language processing but also those that involve vision and hearing. Brain differences are similar among dyslexics, even those who speak different languages. However, the basis of dyslexia in the brain seems to differ among people who use nonalphabetic writing systems, such as Chinese.
Dyslexia is a lifelong condition. With hard work, however, individuals who are dyslexic can succeed in school and in their careers. It is also important that they receive proper diagnosis, appropriate instruction, and support from family, teachers, friends, and others. A known family history of dyslexia provides the opportunity for early identification and intervention. Intervention strategies that focus on strengthening the specific disabilities of poor readers are most effective.
See also Learning disabilities.
