Learning disability

Dislexia

 Dyslexia is a very broad term defining a learning disability that impairs a person's fluency or comprehension accuracy in being able to read, and which can manifest itself as a difficulty with phonological awareness, phonological decoding, processing speed, orthographic coding, auditory short-term memory, language skills/verbal comprehension, and/or rapid naming.

The National Institute of Neurological Disorders and Stroke gives the following definition for dyslexia:

"Dyslexia is a brain-based type of learning disability that specifically impairs a person's ability to read. These individuals typically read at levels significantly lower than expected despite having normal intelligence. Although the disorder varies from person to person, common characteristics among people with dyslexia are difficulty with spelling, phonological processing (the manipulation of sounds), and/or rapid visual-verbal responding. In adults, dyslexia usually occurs after a brain injury or in the context of dementia. It can also be inherited in some families and so on, and recent studies have identified a number of genes that may predispose an individual to developing dyslexia."

Signs and symptoms

 Some early symptoms that correlate with a later diagnosis of dyslexia include delays in speech, letter reversal or mirror writing, and being easily distracted by background noise.This pattern of early distractibility is partially explained by the co-occurrence of dyslexia and attention-deficit/hyperactivity disorder. Although each disorder occurs in approximately 5% of children, 25-40% of children with either dyslexia or ADHD meet criteria for the other disorder. At later ages symptoms can include a difficulty identifying or generating rhyming words, or counting syllables in words (phonological awareness), a difficulty segmenting words into individual sounds, or blending sounds to make words, a difficulty with word retrieval or naming problems (see anomic aphasia)), commonly very poor spelling, which has been called dysorthographia or dysgraphia (orthographic coding), whole-word guesses, and tendencies to omit or add letters or words when writing and reading are considered classic signs. Other classic signs for teenagers and adults with dyslexia include trouble with summarizing a story, memorizing, reading aloud, and learning a foreign language. A common misconception about dyslexia is that dyslexic readers write words backwards or move letters around when reading – this only occurs in a very small population of dyslexic readers. Individuals with dyslexia are better identified by reading accuracy, fluency, and writing skills that do not seem to match their level of intelligence from prior observations.

Cause

 Researchers have been trying to identify the biological basis of dyslexia since it was first identified by Oswald Berkhan in 1881 and the term dyslexia coined in 1887 by Rudolf Berlin. The theories of the etiology of dyslexia have and are evolving with each new generation of dyslexia researchers, and the more recent theories of dyslexia tend to enhance one or more of the older theories as understanding of the nature of dyslexia evolves.

 

References

 

1. ^ ^{a b} "Dyslexia Information Page". National Institute of Neurological Disorders and Stroke. 12 May 2010. Retrieved 5 July 2010.
2. ^ Grigorenko, Elena L. (January 2001). "Developmental Dyslexia: An Update on Genes, Brains, and Environments". Journal of Child Psychology and Psychiatry 42 (1): 91–125. doi:10.1111/1469-7610.00704. PMID 11205626.
3. ^ Schulte-Körne G, Warnke A, Remschmidt H (November 2006). "[Genetics of dyslexia]" (in German). Z Kinder Jugendpsychiatr Psychother 34 (6): 435–44. doi:10.1024/1422-4917.34.6.435. PMID 17094062.
4. ^ Pennington, B.F.; Santerre-Lemon, L., Rosenberg, J., MacDonald, B., Boarda, R., Friend, A., Leopold, D.R., Samuelsson, S., Byrne, B., Willcutt, E.G., & Olson, R.K. (October 24, 2011). "Individual Prediction of Dyslexia by Single Versus Multiple Deficit Models". Journal of Abnormal Psychology 121 (1): 212–224. doi:10.1037/a0025823.
5. ^ Stanovich KE (December 1988). "Explaining the differences between the dyslexic and the garden-variety poor reader: the phonological-core variable-difference model". Journal of Learning Disabilities 21 (10): 590–604. doi:10.1177/002221948802101003. PMID 2465364.
6. ^ Warnke, Andreas (19 September 1999). "Reading and spelling disorders: Clinical features and causes". Journal European Child & Adolescent Psychiatry 8 (3): S2–S12. doi:10.1007/PL00010689. Retrieved 11 July 2010.
7. ^ McCandliss BD, Noble KG (2003). "The development of reading impairment: a cognitive neuroscience model". Ment Retard Dev Disabil Res Rev 9 (3): 196–204. doi:10.1002/mrdd.10080. PMID 12953299.
8. ^ ^{a b} Czepita D, Lodygowska E (2006). "[Role of the organ of vision in the course of developmental dyslexia]" (in Polish). Klin Oczna 108 (1–3): 110–3. PMID 16883955.
9. ^ ^{a b} Birsh, Judith R. (2005). "Research and reading disability". In Judith R. Birsh. Multisensory Teaching of Basic Language Skills. Baltimore, Maryland: Paul H. Brookes Publishing. p. 8. ISBN 978-1-55766-676-5. OCLC 234335596.
10. ^ Valdois S, Bosse ML, Tainturier MJ (November 2004). "The cognitive deficits responsible for developmental dyslexia: review of evidence for a selective visual attentional disorder". Dyslexia 10 (4): 339–63. doi:10.1002/dys.284. PMID 15573964.