Articles

DYSLEXIA
Research Reviews
Dr Lindsay Peer CBE

This material outlined below is an edited and tailored version of that prepared for the DfES by Dr Angela Fawcett, University of Sheffield (2001 - 2002). It does not reflect the personal views of either author, the DfES or of the BDA. There is no endorsement of any approach, product or service intended or implied.

Introduction.
Every so often in the media there are reports of people who claim to have ‘the’ answer for overcoming dyslexia. We know from experience that early identification with appropriate teaching in the right environment will help the majority of dyslexic children. It is possible that a number of therapies will further aid some dyslexic people alongside such teaching. There is no suggestion that these therapies are used in place of this teaching. These are complementary to and not an alternative for dyslexia teaching. However good the claims sound, we must be careful not to jump to conclusions. Whilst it is important to keep an open mind in relation to any therapies proposed, it is strongly advised that any claims as to effectiveness are supported by independent research and evaluation and are open to scrutiny.

In the original review, Dr Fawcett consulted with the original promoters of the therapies in order to gain up-to-date information on work in progress. This is reflected throughout this review.

Note: In order to effectively evaluate any methodology, it would be wise to be aware of the following effects noted in psychology. If we want to see long term and permanent change, we must be aware of them:

1. The Placebo effect: is based on the expectation of change, so that even a sugar pill will produce the effects that have been described.

2. The Pygmalion effect: was found when teachers were simply told to expect great things from certain children. Their re-evaluation of the potential of the children did in fact lead to improvements.

3. The Hawthorne effect: The belief that anything new is effective. The existence of this effect makes evaluation difficult. It needs objective long-term monitoring.

It is therefore very important that those evaluating any therapies are aware of these potential effects and are able to evaluate them critically and objectively. In most cases, dyslexia is a life-long condition, which is inherited. As such, it is important that dyslexic people are given the strategies and skills they need in order to increase their strengths and counteract their weaknesses. It would be unwise to stop the teaching known to be effective and to spend a considerable amount of time on an unproven therapy. It may be that any gains made are only temporary due to one of the three effects described above (Peer).

Dr Fawcett cites an example of this:
A postgraduate student at the University of Sheffield undertook a series of training studies with 5-6 year old children at risk of failure. She compared the success of (i) a well-known phonological package and (ii) balance board training and used (iii) maths training as a control. Surprisingly all three interventions led to both significant improvements in literacy and improved I.Q. scores. However over a six-month period, the benefits of the phonological and the balance board groups remained whereas the maths group dropped back to the level of the untrained controls. In terms of evaluation of interventions, some skills training had generalised to other areas of functioning. Others did not. Parents, teachers and Education Authorities should be seeking long term, sustainable improvements as opposed to solutions that initially appear to present gains that may not be of long term benefit. In such a way, these learners, their parents and their schools will truly benefit.

Part One: Recent and current research.
1. Phonological Deficit.
This is the most developed and supported of the theories of dyslexia. This deficit hypothesis has been widely researched in the US and the UK (significantly Snowling, University of York) since the early 1980s. More than $15,000,000 has been invested annually by the U.S. government via the National Institute for Child Health and Human Development (NICHD).

Phonology is a skill underlying the analysis of both spoken and written language, breaking words into their parts, so that ‘cat’ can be broken into ‘c-a-t’. Phonological awareness is also used in hearing a sound (phoneme) and translating it into a letter which it represents (grapheme).
These skills need to develop at around the age of 5 years if children are to learn to read successfully. If this does not develop, they are reliant on learning to read whole words that they have to recognise visually (orthography). This will limit them in the number of words they are able to learn.

We know that rhyming is a skill that dyslexic children find difficult. This leads on to difficulties with reading, spelling and writing.
Whilst there is general agreement that problems with phonology are associated with dyslexia, it is becoming clear that this is not the only problem.

2. Sensory Deficit.

It is clear that a number of children have problems processing information coming in via the senses (sensory information). This includes information from the ears (auditory) and the eyes (visual).

Tallal in the U.S.A. introduced the ‘rapid processing’ deficit. Stein in Oxford, England introduced the ‘visual magnocellular’ deficit. It has been shown that dyslexic children with these weaknesses take longer to process information than do others who do not have the deficit.

• In the auditory spectrum, they tend to be unable to distinguish sounds if they change rapidly.

• In the visual spectrum, they report that letters may drift or blur. This is due to the fact that when their eyes move on to the next letter, there is an after image from the previous letter.

There is a link between the two systems in many dyslexic people. There is some recent evidence (Molfese, 2000) that infants who were shown to be dyslexic at 8 years of age could be identified at birth by differences in their brain waves. This was concluded after examining speech and non-speech sounds.

3. Speed of processing.

Wolf and Bowers (1999), have brought together the phonological and speed problems in the double deficit hypothesis. This theory suggests that there are two separate sources of difficulty in dyslexia – phonology and processing speed. There is evidence of speed problems for dyslexic children in almost all areas, e.g. pressing a button when choosing between a high and a low tone or saying the names on a full page of colours or pictures. (Nicolson and Fawcett, 1994). This means that dyslexic children need longer to read a word that is familiar to them (van der Leij and van Daal, 1999). This may lead to a strategy of trying to process large chunks of letters in reading, rather than breaking the word down phonologically in order to read unfamiliar words.
This approach makes heavy demands on working memory and limits the number of new words that can be tackled.

The Double Deficit Hypothesis has become a major focus of research recently. Practitioners have noted that it is not enough for children to be accurate to be good readers; they also need to develop fluency as well. Naming speed is a key feature of this research because it identifies weaknesses in:

• speed of access to the name of the picture,
• articulation,
• eye movements to the next picture,

The ability to keep your place and maintain concentration for a whole set of stimuli are essential if such weakness is to be identified.

4. Cerebellar Deficit.
In the early 1990s, a group of researchers at Sheffield University found that dyslexic children had severe problems with a wide range of skills, including balance, motor skill, phonological skill and rapid processing. (Fawcett and Nicolson).

Many of these skills were not language based, suggesting that phonological deficit could not explain all the problems in dyslexia.

This pattern of difficulties was in line with the dyslexic automatisation deficit
(Nicolson and Fawcett, 1990). It suggests that dyslexic children have problems in fluency for any skill that should become automatic with extensive practice. This would include phonological and other skills necessary for the learning process.

The cerebellum is an area at the base of the brain that is known to be associated with motor skill. Recently a link has been noted between the cerebellum and language. Fulbright et al (1999) have identified clear evidence that the cerebellum is involved in both language and cognitive skill, including specific involvement in reading. Direct evidence of cerebellar deficit came from PET scan studies (tests that investigate brain functioning). This showed that dyslexic adults did not show the normal pattern of activation when performing a motor sequence learning task. They produced only 10-20% of the expected level of activation compared with controls.

Summary of the above theories.
All the theories account for at least some of the symptoms of dyslexia. The deficits they predict have been found in varying percentages of dyslexic children. These deficits are observable in brain scans. These are all real deficits.

All the major research groups involved adopt a rigorous approach and produce robust findings.
• The phonological deficit explains many of the difficulties which children show when linking sounds with symbols in reading and spelling.

• The speed or double deficit suggests that there is a speed problem in addition to the phonological deficit. The problems are most severe with those experiencing both deficits.

• The cerebellar deficit suggests that there is a problem in central processing linked to learning and automaticity. This may occur with or without sensory impairment.

How might these theories link together?
There are three ‘levels’ of theory: The biological, the cognitive and the behavioural (Frith, 1997). It is quite possible for all theories to be correct, at different level of explanation. For example:

At the behavioural level: problems in poor reading or rhyming deficits.
• At the cognitive level: problems in phonological awareness, automatisation, and slow processing speed.
• At the biological level: differences in language areas, magnocellular pathways and the cerebellum.

It has been recognised that these levels are different and all are important. Any complete explanation must include all three. The cognitive level should provide the necessary link between the brain and behaviour.
At the BDA conference, 2001, the chair, Prof. Rod Nicolson, talked about the varying perspectives and needs of teachers, researchers, psychologists, the government, parents and dyslexic people themselves. He pointed out that any misunderstandings between the theorists must take into consideration the views of those groups named above. He called this the ‘dyslexia eco-system’.

Co-morbidity (one condition alongside another in the same person)
There is clear evidence of overlap between different developmental disorders, with large percentages (30% or more) of children showing:
• Language impairments
• Dyspraxia
• Attention deficit (with or without hyperactivity)
• Conduct disorders

This is in addition to their dyslexia.

Individual Topics:
Learning.
This is a surprisingly neglected area of research. This is particularly so as dyslexia is also regarded as a ‘specific learning disability’. Some dyslexic children learn to read and develop their phonological skills, areas with which they have the greatest difficulty. However, their skills tend to remain less fluent, more demanding and more error prone, particularly in areas such as spelling.
The ‘Square –Root’ Rule.

A study by Nicolson et al (2001) shows that a simple skill that normally takes 4 sessions to master, would take a dyslexic child 8 sessions. If a complex task took 400 sessions, it would take the child 8000! This suggests that it is important to monitor learning in small, assimilated steps. The support should be appropriate and distinguished from that of other poor readers.

Early Development.
Further research is needed in this area too. We need to try and identify the markers for the sub-types of dyslexia in the youngest groups of children. Early identification and appropriate support are fundamental in ensuring that dyslexic children receive the help they need to develop strategies for later success.

The Brain and Evoked Potentials.
There is considerable mileage in looking at the working of different areas of the brain when performing a range of tasks. The study of brain waves using a network of electrodes is a non-invasive procedure. This can be used with children of all ages, including infants. Early perception (magnocellular) and later processing (cerebellar) before deciding not to respond to auditory (a tone) or visual stimuli (a cross) will explain the relative contribution of these deficits (Shankerdass, 2001).

Part Two: Established and New Therapies.
1. Occlusion (eye patching).
This theory based on the work of Stein dates back to the 1980s. It suggests that some children who are dyslexic will have problems because their eyes do not work well together. This is known as ‘unstable fixation’. Stein has measured binocular stability by performance on the Dunlop test over the past twenty years. The Dunlop test presents 2 slides of a house and a post, which are viewed through an instrument known as a synoptophore. When the eyepiece tubes are moved away from each other, one of the posts seems to move towards the door of the house just before fusion breaks. Stable fixation is shown when children respond with the same eye each time. This demonstrates that they have a dominant eye.

However there are problems with this test which Stein acknowledges. Bishop, (1989; Stein, 1989) noted that it may be unreliable and is difficult to administer. It is also complex for children to perform. When children show that they have unstable vergence, they may complain that the words move around on the page. It is therefore more difficult for them to learn to read. For children under the age of 10, Stein suggests that they patch one eye. This forces the visual system to switch to using the uncovered eye. Stein and colleagues tend to cover the left eye because most children write with their right hand. They have noted that even left handers do better with the left eye occluded.

Whilst this is an interesting area of research, it is not clear how many children show unstable vergence. Furthermore it is not clear whether it is associated with reading difficulties - due to results seen against those of a control group (Stein’s data by Bishop, 1989, at the Royal Society).
Stein is currently advocating the use of eye movement exercises for children with unstable vergence. Pavlidis in 1981, also suggested the use of eye movements in following a pattern of moving lights. This test is still under development in Greece. More recently a paper by Fischer in 2000, suggests that visual problems in dyslexia could be treated with a series of eye movement exercises.

Paula Tallal has developed a computer program entitled ‘Fast ForWord’. This program is designed to improve rapid processing skills in Specific Language Impairment (SLI) and Dyslexia. http://www.fastforword.com.

She has claimed (1993) that dyslexic children take longer to process sounds which change rapidly. This is tested with high and low tones, or the sounds ba and da, which are only different in the first few milliseconds. Dyslexic children can’t tell the difference between sounds if they are presented close together. This means that they are likely to have problems with phonological awareness. This theory has been under development for the past 25 years. In terms of intervention, the Fast ForWord program has been designed to train children in just those changes that prove most difficult for them. In order to help them, they hear sounds that are drawn out by 50% so that they sound like whale noises. With this prolonged presentation, they learn to complete the task.

The program has a range of levels in it. Children are asked to complete about 10 hours practice a week in 20-minute sessions for 6-8 weeks. It has been shown to lead to significant gains on the games and on the Tallal test. The children have shown improvements in dealing with natural language.

In a recent study Hook et al. 2001, found that their Fast ForWord group showed significant gains in phonemic awareness. However after 2 years, the children’s spoken language and reading were no greater than the control group. The control group received no intervention. The researchers also claim that the results were not as good as those children undertaking a more traditional approach. The claim was that the program was too inflexible. As a result, a new program is being developed called ‘Fast ForWord Language to Reading’. It is based on the use of normal consonants.

Finally, the Fast ForWord website shows that over 25,000 children in the U.S. have now been trained on the program. Over 90% have shown improvement on some of the parameters tested.

Arnold Wilkins - the effects of coloured lenses and overlays on dyslexia.

The rationale for this work is that high levels of headache and visual symptoms are associated with dyslexia. Evidence is coming through which shows that strong visual stimulation can make life very difficult for dyslexic people e.g. black ink on white paper. Coloured lenses act by blocking the over-stimulation. This is the basis for the Irlen-Meares lenses. Wilkins uses a colorimeter that allows a child to select the colour that they find most useful in reducing the effects of glare. This colour can be made into a coloured overlay or built into a pair of glasses. For children who experience these problems, coloured overlays may well increase the rate of reading and reduce visual stress.

Alex Richardson – The effects of fatty acid supplementation in ADHD and Dyslexia.
Fatty acid deficiencies have been linked to dyslexia. This is based on clinical signs of deficiencies in adults. Also there is evidence that deficits predict the level of reading failure in children. Deficits have also been associated with behavioural impairments, such as Attention Deficit and Hyperactivity Disorder (ADHD). Clinical signs of fatty acid deficiency (dry hair and skin) have been linked to blood levels of fatty acid (FA) in 97 dyslexic children in relation to the severity of their reading deficits. A larger fatty acid deficiency is linked to poorer reading. However, there are six differences, with low fatty acid in boys linked to lower auditory memory and poorer spelling. There is no significant links in girls.

Richardson and colleagues have been investigating the impact of adding a fatty acid supplement. Following tests of 41 children aged 8-12 with specific learning difficulties (the majority dyslexic), results showed that the control group made no change. The active treatment group however showed reduced:

• psychosomatic complaints
• anxiety
• cognitive problems and
• significant changes in the DSM (Diagnostic and Statistical Manual of Mental Disorders). It can be concluded from the data fatty acids may produce a positive effect in the areas outlined above. However, it is not known as yet whether or not they improve reading. This approach is promising and has been shown to have beneficial effects in some subject groups. The data of particular interest are not yet available. Nevertheless, the changes that the intervention has produced in attention should be sufficient to facilitate learning.

Martin McPhillips – Training children with persistent primitive reflexes.
The exercises involved in the reflex intervention are based on the repetition of primitive reflexes. They are presented in a video drawn from a television documentary. The exercises were based on body and eye movements.
This is an interesting approach, which is standing up well to evaluation. However it seems that many of the children involved may be those who fall into the low intelligence group. The theoretical basis of the primitive reflex deficit has not yet been explained. Even Martin McPhillips himself seems uncertain of the basis for these difficulties.

Wynford Dore – The Dyslexia, Dyspraxia and Attention Deficit Centre (DDAT) – balance training.
Unlike the other interventions outlined so far, Dore is not using techniques based on his own theories. He has adopted techniques from a variety of different groups. His plan is to put together a selection that will cover the known difficulties in a range of developmental disabilities.

Dore is not a researcher himself, but is trying to satisfy academic criteria. This has proved one of the more controversial of the therapies, although a series of studies are in progress which suggest that the interventions may be useful with some children.
Any information given here is drawn form the DDAT website and NOT from published papers.

Baseline assessment from July 2001 included a computerised version of Dyslexia Screening
Test, including:

• 1 minute reading
• 2 minute spelling
• nonsense passage reading
• backwards span and segmentation.
• posturography
• a sensitive measure of the integration of vestibular, visual and proprioceptive information
• eye tracking
• neurological tests including primitive reflexes such as the Moro and the Romberg, vestibular ocular reflex
• speed of alternating hand movements, and
• effects of stress.

Psychological reports are collected, giving a full educational and medical history. The attention deficit scales from the Diagnostic and Statistical Manual of Mental Disorders (DSMIV) are administered by parents and testers. Children are asked to evaluate their own abilities.
One of the problems for an intervention of this type is that it depends on the compliance of the parents in supervising the exercises. As problems of this type tend to run in families, some parents have difficulty in following through. The current plan is to involve Local Education Authorities (LEAs) in the research.

Intervention is based on a series of exercises, training balance and vestibular skills. There are videos available based on the higher levels of intervention. Exercises might include:

• balancing on a wobble board;
• standing on one leg, while counting and throwing bean bags;
• extending the arms upwards and holding them in place without wobbling, while standing on a large cushion.

They differ from McPhillips exercises because they involve the whole body, rather than the head, neck and arms. The intervention is considered complete when the child or adult is able to score 100% on the posturography test, and 80% on the eye movements. Performance is checked 2 months later, to make sure there is no regression. Fatty acids may then be used to maintain progress.

In summary, this technique appears to have considerable potential in bringing together aspects of all the other non-traditional approaches, apart from Tallal’s. The proposers seem committed to undertaking ongoing research to evaluate their intervention rigorously. A further series of evaluations are in preparation.

Note that, although promising, this material has not yet been peer reviewed.
Conclusions from an evaluation of non-reading therapies.
A number of ways to evaluate the effectiveness of these therapies have been cited:

o standardised tests
o curriculum based tests
o underlying skills (e.g. Dyslexia Screening Test)
o quality of life – self esteem and confidence
o behaviour and motivation

There is a range of interventions available – and there may be different reasons why they work. Encouraging children to succeed in novel ways might be helpful.
Peer cautions that we must ensure that there is no placebo effect. Therefore, constant monitoring is advised. Every year of failure is a year lost.

Summary.
A combination of traditional teaching and complementary therapy seems the most likely to be effective. This will produce multi-sensory teaching for children with difficulties. Whilst the majority will develop with these methodologies, there will be a relatively small number for whom specialist 1:1 or small group teaching will be inevitable if progress is to be made and potential is to be reached.
Disclaimer.
As in all research, on-going change is positive and inevitable. Those interested in specific developments may wish to keep up-to-date by referring to the web sites of each organisation. These are outlined above.
References.
For those wishing to read the original research and develop their understanding further references are listed below:

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