The term dyslexia is used to describe difficulty in the acquisition of reading, writing and spelling skills but not all poor readers are dyslexic. The child's learning difficulties may be caused by:
- Visual problems through not being able to recognise shape and form.
- Reading speed, accuracy or comprehension.
- Phoneme segmentation (cannot see or hear the components and then put them together to create meaning and to spell the words).
The Diagnostic and Statistical Manual Fourth Edition (DSM-IV) criteria for the diagnosis of dyslexia are:
- Reading achievement substantially below that expected for the person's age, measured intelligence and age-appropriate education.
- The disturbance in reading ability interferes with academic achievement or activities of daily living that require reading skills.
- If a sensory deficit is present, the reading difficulties are in excess of those usually associated with the specific sensory deficit.
- This is reading impairment following some form of brain insult in individuals with previously normal levels of reading ability.
- It is frequently associated with aphasia where patients will exhibit a type of dyslexia in keeping with their form of aphasia, eg fluent aphasics will have difficulties understanding printed word meanings while non-fluent aphasics will have trouble with grammatical aspects of reading.
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Dyslexia affects all kinds of people regardless of intelligence, race or social class:
- Estimates of prevalence vary according to the definition of dyslexia and the way in which it is assessed. The British Dyslexia Association suggest that 4% of the population will be severely dyslexic (requiring support at school and beyond) and a further 6% may have mild or moderate dyslexia.
- Some reports suggest that up to four times as many boys as girls are dyslexic. However, this may not reflect the true situation as affected boys may be more likely to be disruptive in class and therefore recognised as needing outside help. Girls' language skills exceed boys' language skills throughout most of school and therefore boys are more likely to appear as failing.
- There is a genetic predisposition for reading difficulties. It appears that a number of genes at different loci (rather than a single locus) may be responsible.
Dyslexia usually presents at about the age of 7 or 8 years as the child's difficulties become clear in the school setting. Common signs of dyslexia include:
- Hesitant and inaccurate reading.
- Need to re-read materials to gain an understanding.
- Difficulty with sequences, eg putting dates in order.
- Erratic spelling.
- Reversal of letters (occurs in all children but less frequently than those with dyslexia).
- Auditory language problems or visual spatial problems, which may contribute to difficulties with reading and spelling.
- Inability to distinguish sounds or shapes on the page.
- Associated features include poor spelling and handwriting, and mathematical difficulties.
- Assessment is usually carried out by an educational psychologist following a referral from a parent or teacher.
- Standardised measures, such as the Weschler Intelligence Scale for Children, are used to assess general intellectual ability. More specific tools (eg the Dyslexia Early Screening Test for testing early years, the Dyslexia Screening Test and the Aston Index) are used.
- The educational psychologist then investigates whether a child does not understand the meaning of words (semantic difficulty) or cannot see or hear the components and then put them together to create meaning and to spell the words (phoneme segmentation).
- About 50% of those with dyslexia also have dyscalculia (difficulty with acquiring arithmetical skills).
- It is important to identify language difficulties or any hearing problems which may be the underlying cause or contribute to the reading and spelling difficulties.
- There is an overlap between attention deficit hyperactivity disorder (ADHD) and a reading disorder. Children with a reading disorder are twice as likely as other children to have ADHD and children with ADHD are twice as likely to have a reading disorder.
- Dyspraxia is more common in people with dyslexia.
- Short-term memory, mathematics, concentration, personal organisation and sequencing may be affected.
There are a number of educational methods that can help people with dyslexia overcome their difficulties with reading and writing:
- Children with dyslexia require specialist teaching; many schools now have specialist provision for dyslexic children.
- Providing supportive home and school environments is essential. Parents and teachers should be strongly encouraged to praise and support the child.
- Teaching should be multi-sensory (include visual, auditory, movement and tactile elements), as children with dyslexia learn better when they can use as many different senses as possible, eg writing the letter in the air at the same time as saying the letter and its sound. Teaching should also be highly structured.
- Phonics: the sounds that the letters represent are emphasised so that the child gradually connects the visual pattern of words to the auditory pattern of words.
- Computers: many children with dyslexia find it easier to work with a computer than write in a book, with the additional benefit of using the spell checker. Computer software programs are available to teach phonemic recognition and can provide effective adjuncts to tutoring and classroom intervention.
- Eye checks: regular eye checks are particularly important for any child or adult who has difficulties with reading or spelling and who may be dyslexic. Eye problems do not cause literacy problems, but can be a contributory factor.
- Colour overlays: some people with dyslexia are light- or colour-sensitive (Meares-Irlen syndrome), eg bright sunlight or fluorescent light may cause particular difficulties, black print on shiny white paper may be uncomfortable for the eyes, whiteboards may be too shiny, pattern glare may also be a problem. Transparent colour overlay filters (eg Irlen coloured overlay lenses) can be used to improve reading performance. It may also be helpful to have coloured paper for writing and adjust the colours and brightness on computer screens.
- A number of other educational methods have been studied, eg exercise based therapy, which remains controversial.
- Rates of behavioural problems, social maladjustment, anxiety, withdrawal, and depression are higher in children with reading disorder.
- Social problems may increase as children get older as they fall further behind with reading skills.
- Although some compensation can occur over time, dyslexia is usually persistent and can have a severe effect on academic achievement.
- The effectiveness of treatment depends on the initial severity of the dyslexia. The earlier the intervention, the better the outcome.
- With appropriate intervention (speech and language therapy) and teaching, affected children with expressive phonological and vocabulary difficulties can achieve an adequate literacy level to function in society, although their reading abilities may still lag behind their peers.
- Outcomes for patients with expressive syntax difficulties are more mixed, and interventions for those with receptive language difficulties need more research.
- However, many people affected by dyslexia have good ability in lateral thinking and shine in such fields as the arts, creativity, design and computing.
Further reading & references
- Logsdail S; Synaesthesia. BMJ. 2009 Sep 4;339:b3191. doi: 10.1136/bmj.b3191.
- Tynan WD, Learning Disorder, Reading, eMedicine, Feb 2008
- British Dyslexia Association
- Pennington BF, Lefly DL; Early reading development in children at family risk for dyslexia.; Child Dev. 2001 May-Jun;72(3):816-33.
- Bouldoukian J, Wilkins AJ, Evans BJ; Randomised controlled trial of the effect of coloured overlays on the rate of reading of people with specific learning difficulties. Ophthalmic Physiol Opt. 2002 Jan;22(1):55-60.
- Reynolds D, Nicolson RI; Follow-up of an exercise-based treatment for children with reading difficulties. Dyslexia. 2007 May;13(2):78-96.
- Rack JP, Snowling MJ, Hulme C, et al; No evidence that an exercise-based treatment programme (DDAT) has specific benefits for children with reading difficulties. Dyslexia. 2007 May;13(2):97-104; discussion 105-9.
- Demonet JF, Taylor MJ, Chaix Y; Developmental dyslexia. Lancet. 2004 May 1;363(9419):1451-60.
- Law J, Garrett Z, Nye C; Speech and language therapy interventions for children with primary speech and language delay or disorder. Cochrane Database Syst Rev. 2003;(3):CD004110.
|Original Author: Dr Colin Tidy||Current Version: Dr Hayley Willacy|
|Last Checked: 18/02/2011||Document ID: 1588 Version: 22||© EMIS|
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