Dyslexia - from the Greek, meaning difficulty with words - was first identified in 1896, when Dr Pringle Morgan published a paper on “congenital word blindness” in the British Medical Journal. Dr Morgan had been studying a 14-year-old boy called Percy, the “eldest son of intelligent parents” who “would be the smartest lad in the school if the instruction were entirely oral”. He described how “in spite of this laborious and persistent training, he can only with difficulty spell out words of one syllable”.

Asked to put down in words the phrase “carefully winding the string round the peg”, Percy wrote: “Calfuly winder the sturng rond the Pag”. “This inability,” Dr Morgan concluded, “is so remarkable and so pronounced that I have no doubt it is due to some congenital defect.”

What causes dyslexia?

It took until 1997 for scientist to prove Dr Morgan right and identify a genetic connection. Researchers at Oxford University and the Wellcome Trust studied 100 families with two or more dyslexic children, and discovered they all had irregular patterns of genes in one chromosome. But while many experts believe dyslexia is almost always hereditary, no one is quite sure of the factor that causes it. “If one parent is dyslexic, the children of that couple have a 50 per cent chance of being dyslexic,” says Shirley Kramer, chief executive of the Dyslexia Institute. Advances in neurological science have identified the cerebellum, which governs balance, co-ordination and motor skills, as being the section of the brain that does not function fully in dyslexics.

Brain scans on adult dyslexics had already shown neural disruption in the cerebellum, but last year, for the first time, researchers at Yale University used functional magnetic resonance imaging to scan the brains of children with dyslexia. They found similar patterns in the brains of children as young as seven, emphasising the need for early intervention and help at school.

Research published last year by scientists at the University of London suggested that dyslexic children had difficulty recognising the rhythms of speech centred on the start of vowel sounds. This may explain the difficulty some have in making rhymes.

Is there a cure?

As it is a congenital condition and not a disease, dyslexia cannot be cured. People are born with it and, with help, they can learn to live with it.

Are English speakers more susceptible?

English is a notoriously complex language, with around 40 sounds but 1,000 ways of spelling them - proportions similar to French but much higher than Italian, which has a more standard phonetic framework of about 25 sounds and 33 spellings. Because dyslexia is essentially an inability to translate speech sounds into or from written language, any deviation from standard phonetics adds to the difficulties. Consequently, the incidence of dyslexia is much higher in France and Britain than in Italy.

How many people are affected?

Dyslexia is the most common special educational need, affecting about 4 per cent of the population. This means about 350,000 schoolchildren, and almost three million people in total, are dyslexic. Another 6 per cent have dyslexic traits. Research by the Dyslexia Institute shows the incidence is about the same in both sexes, but boys are three times more likely than girls to receive special help at school, possibly because dyslexic girls are better at developing coping strategies or less likely to show their frustration.

How can you tell if someone is dyslexic?

For years, dyslexic children were branded as lazy, careless or stupid. It was seen as a middle-class parent’s complaint when their offspring were not performing to expectations. “Dyslexia is an ‘equal opportunities’ disability,” says Shirley Kramer. “It can affect anybody.” There is no simple diagnostic test either. But there are many behavioural traits that, if they occur together, may indicate dyslexia. Early signs can include putting clothes on the wrong way round, an inability to distinguish between left and right or to learn simple rhymes. Among very young children who are dyslexic, the first milestones of physical development are delayed, and learning to walk without first crawling may be an indicator. In older children, there may be a tendency to spoonerisms (for example, par cark), spelling the same word differently, confusing words (for example, dog for god) and poor literacy. They may have difficulty copying from the board, interpreting written instructions, organising work or remembering passages of text, and have erratic spelling and poor handwriting.

Isn’t dyspraxia something to do with dyslexia?

A host of other conditions can occur with or separately from dyslexia but share certain characteristics. Dyspraxia - a difficulty with motor co-ordination characterised by clumsiness - often overlaps with dyslexia.

Problems associated with numeracy - dyscalculia - are exacerbated by an inability to recognise plus and minus signs, for example, and some dyslexics may have difficulty reading music.

Haven’t some dyslexics won damages for non-diagnosis?

There have been several high-profile court cases in which former pupils have sued their education authorities for damages. In 1998, Pamela Phelps was awarded pound;46,650 from the London borough of Hillingdon for its failure to recognise and help with her dyslexia. Ms Phelps, who was born in 1973, had been assessed by an educational psychologist, who failed to diagnose her dyslexia. She passed through school without any appropriate support and found it difficult to get a job after she left.

She decided to take legal action against the borough for negligence. The council appealed against the award and Ms Phelps was ordered to return the money, but in 2000 the initial decision was upheld by the House of Lords.

This final ruling established the right of dyslexics to seek compensation for personal injury where the education system had failed them.

Last year, 25-year-old Robin Johnson was awarded pound;52,500 against Stockport LEA after he was bullied at school because of his severe dyslexia, which was not diagnosed until he was 13.

Legal actions such as these are likely to become increasingly common. Jack Rabinowicz, the education law expert who represented Ms Phelps, has around 50 cases pending. He says that while the legal framework for such actions is not yet fully formed, they could become as common as claims for medical negligence and personal injury compensation. “There are issues that make it more difficult to establish the case; you don’t know how the child would have turned out but for these things,” he says. Parents and schools tend to contest the blame, he adds. “A lot of buck-passing goes on.”

What’s the best way to help as a teacher?

Tried and tested classroom methods can alleviate many of the difficulties.

Early identification is crucial as non-diagnosis can lead children to develop secondary problems of misbehaviour or work avoidance. On average, one child in every class will be dyslexic, so it is important that all teachers should be aware of their needs.

At key stage 1, dyslexic children can usually be taught alongside their peers; many of the strategies designed to help them are good practice for all children learning to read. But they will need specialist tuition as they progress through school. Use plenty of praise and encouragement. Work should be marked for content rather than spelling, with good lines of text ticked. Use a dot rather than a cross next to those with errors. Write important words clearly on the board and give the child plenty of time to copy them down. Instructions on homework, things to remember to bring to school, and notes to parents should be written in a notebook.

Dyslexic children usually respond best to information presented in non-written forms - such as graphs, charts, pictures or tapes - and when given the opportunity to present their own work in these ways. But always be aware that dyslexics can get tired. They often yawn when you’re explaining things to them, which can be interpreted as boredom or insolence. It isn’t; they’re just shattered. If they start to yawn, give them a quick break and some physical task to get oxygen back into their brains.

Acquiring computer skills can help dyslexic children, who usually find typing easier than handwriting. While spellcheckers are an obvious aid, the repeated action of typing a word will leave an imprint of the correct spelling on a child’s motor memory. Any child you believe may be dyslexic should be referred to your school’s special needs co-ordinator, who may arrange an assessment. With help, dyslexia is no bar to a long and continuing education. The Higher Education Statistics Agency estimates there are about 10,000 dyslexics studying at university.

Are there any treatments?

Educationists have been aware of a physiological element to dyslexia since the 1970s, as a result of which several programmes of treatment have been developed. In dyslexics, the part of the brain that fast-processes visual information has abnormalities. This accounts for the slower reading and writing speed of dyslexic children, but it also has repercussions for their physical abilities. So dyslexic children attempting to catch a ball will react quickly enough, but put their hands in the wrong place. The theory says that practising these simple movements can strengthen the neural connections and have a positive knock-on effect on reading and writing.

Brain Gym, developed by American doctor Paul Dennison (himself a dyslexic), is a system of exercises designed to stimulate the cerebellum by replicating the movements young children make when their skills of balance and co-ordination are developing. There are 26 simple movements, such as Lazy 8s (drawing a horizontal figure eight in the air with your thumb) and cross-crawls (touching your right knee with your left hand and vice versa) which are supposed to help specific brain functions.

The DDAT centres

Everything from eating more fish oils to wearing coloured contact lenses has been suggested as a possible aid for dyslexics. Other commercially available treatments have attracted controversy. The Dyslexia, Dyspraxia and Attention Deficit Treatment Centre (DDAT) was opened two years ago by millionaire businessman Wynford Dore, whose now grown-up daughter is severely dyslexic. DDAT has eight centres in the UK, one in Australia and another in the US; it charges around pound;1,400 for its individually tailored treatments. Using sophisticated equipment to measure the cerebellum’s function, therapists will ask the dyslexic client to perform a series of short, simple exercises daily - such as tying a knot while balancing on one foot or throwing a bean bag from one hand to another - over a period of several months. DDAT claims “97 per cent of our patients complete the programme without the symptoms they come with”, and has said that in some people talk of a cure is not misplaced.

The ITV current affairs show Tonight with Trevor McDonald reported in January last year on two families that went to the centre for treatment.The programme was later criticised by the Independent Television Commission for describing the methods as a “miracle cure” and “revolutionary breakthrough” and raising the hopes of sufferers. But last November, research by David Reynolds of Exeter University (former head of the Government’s numeracy task force and a non-executive director of DDAT) into 35 children who had received treatment at the centre described “significantly greater improvements” in manual dexterity, reading and verbal fluency compared with their peers. SATs results at the school involved, Balsall Common primary in Warwickshire, have improved.

Professor Rod Nicholson of Sheffield University has conducted extensive research into the role of the cerebellum, and acted as a consultant to DDAT when it was setting up its programme. While the link between abnormalities in the cerebellum and dyslexia are well established, correcting the outward signs of this malfunction - poor co-ordination and balance - does not necessarily “cure” dyslexia, he says. “It is another step to training the cerebellum that will therefore improve your reading.” Nevertheless, he says, the results are “extremely promising”. He has compared the difficulties faced by dyslexics when reading to driving in a foreign country: it’s stressful and tiring and difficult to decipher the directions. “We have to try to keep an open mind and to analyse all the successes and failures. In 10 years’ time we will have a much better understanding.” The Dyslexia Institute has described the findings as “interesting” and useful as a complementary therapy, particularly to people at the dyspraxic end of the spectrum.

Are there any benefits to having dyslexia?

There is some evidence that the neurological circuitry that makes people dyslexic often bestows strengths in other areas such as visual and spatial awareness, practical and problem-solving skills and imaginative work. Many dyslexics flourish in business, the arts, IT and creative industries.

Albert Einstein, Leonardo da Vinci and Rodin all had dyslexic traits, although the condition was not identified in their lifetimes. Eddie Izzard, Richard Rogers, Richard Branson, Jackie Stewart, Anita Roddick, Jamie Oliver and Robbie Williams all have dyslexia. The photographer David Bailey, also dyslexic, has said: “Dyslexia is a kind of privilege because it helps you to see differently from other people.”

Alan MacDowell is a dyslexic who runs a consultancy to increase awareness among major employers such as HSBC, Waitrose, Unilever and Cadbury’s. He says the emphasis on trying to teach dyslexics to read and write misses the point. Dyslexics, he says, have a creativity and visual awareness that is vastly underrated. “People perceive dyslexia in the wrong way,” he says.

“It’s a positive attribute and the advantages far outweigh the negatives.

The traditional view of dyslexics is, ‘You are broken and we have got to fix you’. But if we didn’t think in a certain way, Einstein wouldn’t have discovered what he did.”

Main text: Harvey McGavin Pictures: Science Photo Library Neil TurnerCorbisChannel 4Additional research: Tracey Thomas Next week: School toilets