Dyslexia (cont.)

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What causes dyslexia?

Children with dyslexia have difficulty in learning to read despite traditional instruction, at least average intelligence, and adequate motivation and opportunity to learn. It is thought to be caused by impairment in the brain's ability to process phonemes (the smallest units of speech that make words different from each other). It does not result from vision or hearing problems. It is not due to mental retardation, brain damage, or a lack of intelligence.

The causes of dyslexia vary with the type. In primary dyslexia, much research focuses on the hereditary factors. Researchers have recently identified specific genes identified as possibly contributing to the signs and symptoms of dyslexia. This research is very important because this may permit the identification of those children at risk for developing dyslexia and allow for earlier educational interventions and better outcomes.

What are the different types of dyslexia?

  • Primary dyslexia: This is the most common type of dyslexia, and is a dysfunction of, rather than damage to, the left side of the brain (cerebral cortex) and does not change with age. There is variability in the severity of the disability for Individuals with this type of dyslexia, and most who receive an appropriate educational intervention will be academically successful throughout their lives. Unfortunately there are others who continue to struggle significantly with reading, writing and spelling throughout their adult lives. Primary dyslexia is passed in family lines through genes (hereditary) or through new genetic mutations and it is found more often in boys than in girls.
  • Secondary or developmental dyslexia: This type of dyslexia is caused by problems with brain development during the early stages of fetal development. Developmental dyslexia diminishes as the child matures. It is also more common in boys.
  • Trauma dyslexia: This type of dyslexia usually occurs after some form of brain trauma or injury to the area of the brain that controls reading and writing. It is rarely seen in today's school-age population.

Other types of learning disability include:

  • The term visual dyslexia is sometimes used to refer to visual processing disorder, a condition in which the brain does not properly interpret visual signals.
  • The term auditory dyslexia has been used to refer to auditory processing disorder. Similar to visual processing disorder, there are problems with the brain's processing of sounds and speech.
  • Dysgraphia refers to the child's difficulty holding and controlling a pencil so that the correct markings can be made on the paper.
Medically Reviewed by a Doctor on 10/12/2015

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