On the one hand there are parents - well-read and well-meaning - who swear by Ritalin, who pop pills into the mouths of their sleeping children half an hour before they wake up to spare them the agony of getting off to school with untreated ADHD. And a paediatrician practising in Sussex who believes that up to 5 per cent of children suffer ADHD, and that their treatment could dramatically reduce disruption in Britain’s classrooms.

On the other, there are general practitioners and teachers who are uncomfortable about administering psychological drugs, and who profess deep scepticism (and occasionally total ignorance), about the diagnosis, treatment - and even the existence - of the disorder.

But what is ADHD? An American import useful for labelling challenging children who are difficult to teach? Or a sophisticated tool of analysis which could be used to help considerable numbers of children currently failing in and out of school?

And what is Ritalin? A cheap chemical cosh which can subdue the symptoms of disturbed children without tackling their problems? Or a tried and tested medicine which can reach parts of the brain that classroom interventions alone simply can’t tackle?

Attention deficit hyperactivity disorder is well-established on both medical and educational agendas in the United States. The condition has been recognised in the Diagnostic and Statistical Manual (DSM) of the American Psychiatric Association since 1980, in different forms, and some American studies suggest that as many as 6 to 8 per cent of children meet the definition. ADHD is recognised as a category of handicap under federal law, and states are required to make special educational provision for children who have the disorder. Prescription of Ritalin is rising “like a flood tide”, says one observer of the American scene.

ADHD is a complex syndrome. Its exponents believe that it is a neurochemical disorder, an imbalance which inhibits the release of chemicals which carry messages back and forth in the brain. This leads potentially to a whole cluster of symptoms in children (and some adults), including being unable to filter out distractions, or think ahead, or keep instructions in mind.

In educational terms, the effects are likely to be fairly disastrous. Typically they include difficulty in starting, or finishing work, slowness, and problems in organising thoughts, understanding directions, recalling learned material and dealing with unstructured tasks.

ADHD is believed to be hereditary is some cases, more common in boys than girls and to persist into adulthood in about half of all cases.

But ADHD remains controversial even in the United States. One of the chief difficulties is its diagnosis. The primary visible characteristics are inattention, impulsiveness and hyperactivity - characteristics which are present in everyone to some degree, some of the time. Leading US expert Dr Thomas Brown of Yale University, in a recent talk in London, said diagnosis was “dimensional” rather than “categorical”. In other words, like depression, not pregnancy.

Various brain scanning techniques have shown significant differences in the ADHD and non-ADHD brain, although scanning remains an inexact art. But children are not diagnosed through brain scans but through assessment of a range of behavioural symptoms. “We were in the paediatrician’s office,” said one New York mother of a then six-year-old child. “She was pulling papers off his desk and tearing up his office. She was incapable of sitting on a chair and I couldn’t control her without physically sitting on her. The paediatrician said ‘look at her. I really hope you’ll consider this drug’.”

Since the early 80s, American thinking has evolved to separate out the hyperactivity element of the disorder - US researchers believe it may not be present at all in 30 per cent of cases, or can wane with time in others. Children with attention deficit disorder (ADD) but without hyperactivity, says Dr Brown, “more closely resemble stereotypes of ‘space cadet’ or ‘couch potato’ than the ‘whirling dervish’ of ADHD”. The American slang underlines the extent to which this appears an imported phenomenon, and may go some way to explaining the high levels of scepticism among some professionals here.

But attention deficit hyperactivity disorder is beginning to be recognised by the UK medical establishment. Eric Taylor, professor of developmental neuropsychiatry at the Maudsley Hospital, is one of the few home-grown experts in a field dominated by Americans and Australians. Professor Taylor, whose interest in hyperactivity has spanned decades, believes that ADHD is both over and under-diagnosed in Britain.

He believes that ignorance of the condition here, combined with exaggerated fears of Ritalin, is a dangerous combination. “There is a very low level of knowledge in this country. And it is worrying because it can lead to the wrong treatment. So some children are getting biological treatment when what they need is counselling. And vice versa. I think we both undertreat and overtreat. ”

On the ground, parents - and possibly teachers - are more concerned about under-treatment. As the case histories show (see page 4), a child with untreated ADHD can wreak havoc on his own life, and those around him. Or her.

LADDER, the national learning and attention deficit disorders association, held its first public meeting in January 1993. “One hundred and three people turned up,” says chairman Stan Mould, “most of them in tears.” Membership has now grown to about 1,000, two-thirds of whom are parents; the rest interested professionals. While knowledge is growing, it is not widespread and many parents believe that they arrive at the GP’s surgery or headteacher’s office knowing far more about ADHD than most professionals.

Expert treatment is in short supply. Professor Peter Hill of St George’s Hospital Medical School, London, chairs the section of child and adolescent psychiatry at the Royal College of Psychiatrists. He runs one of only two NHS specialist ADHD clinics in the country - the other is Professor Taylor’s at the Maudsley - and closed his waiting list when it reached the year 1998.

While the ADHD and ADD labels may be contentious, it is the use of Ritalin and other drugs to treat the disorders that is causing most controversy in this country. Much of the anti-Ritalin feeling stems from a gut reaction against the idea of large numbers of children having their behaviour altered through drugs. Alarm bells start ringing in the national psyche when we hear that between 2 and 3 per cent of north American children are on psychological drugs.

And the commonsense perspective that this must be wrong is reinforced by Professor Hill. “Hyperactivity is common,” he says. “To start recognising it as a disorder requires a cut-off point of severity. The point at which it’s appropriate to look at it as a disorder is a social question.”

The official definition used in Britain is the World Health Organization’s classification of “hyperkinetic disorder”, more cautious and specific than the American model and likely to trawl far fewer children in its net. According to Professor Taylor, only around one in 200 children in the UK would meet the rigorous WHO criteria. He says one child in a thousand is likely to need treatment with drugs.

The current Ritalin debate in Britain centres largely on the activities of Dr Geoffrey Kewley, an Australian paediatrician who has set up his own ADHDADD clinic - the Learning Assessment Centre - now in Horsham, West Sussex. Two-thirds of his patients are NHS referrals, one-third private. Debate is the polite word for it. More accurate might be to say that an acrimonious row has blown up between Dr Kewley and various local headteachers. The two sides have been inaccurately characterised in parts of the media as being blindly-pro (Dr Kewley) or entirely-anti (the heads) the use of Ritalin.

Certainly, Dr Kewley is an enthusiastic proponent of both the ADHDADD syndrome, and its treatment by drugs, with other methods. He believes that too many hyperactive andor inattentive British children are seen as the naughty products of bad parenting, and are being suspended or excluded from mainstream schools unnecessarily. And that Ritalin can help many of them. “Day in, day out I see children who come in with all the complications of ADHD or ADD. Three months later they come back as different children, and their families as different families. They’re switched back on. Their self-esteem, their interpersonal relationships, their well-being is so greatly improved. They’re concentrating better, they’re less hyperactive and they’re starting to learn. It’s chalk and cheese.”

But a small group of concerned West Sussex headteachers set up a working party to look into ADHD and its treatment locally, and have raised issues which they think need airing. The first is that some believe that too broad a range of local children are being diagnosed ADHD, and that the condition is being used as a catchall. Terry Ferber is head of Crawley’s Deerswood School for children with moderate learning difficulties. “The range of children in my school that have been diagnosed ADHD or ADD is just huge,” he says. “Some of whom are autistic, some of whom have different types of learning difficulties and some of whom present no difficulties whatsoever in school. To find them all being given the same label is very worrying.”

Dr Kewley uses the broad-based north American criteria in his diagnoses, which may go some way towards explaining the charge being made locally that he is over-diagnosing. He counters that in Britain ADD and ADHD are under-recognised. “Having ADHD is a fast track to getting complications,” he says. “You’ve got a 30 to 40 per cent chance if you’ve got ADHD of being excessively oppositional, or conduct disordered, or dyslexic. People see those things, but fail to recognise the underlying ADHD. I would think that any head of an MLD school should be cognisant of ADD and be prepared to think about it. And I would think it may well be that 80 per cent of children in EBD schools have co-morbid ADD.”

The second area of concern of the West Sussex heads is Ritalin. What concerns them is not the use of Ritalin per se, but what they perceive as inadequate monitoring of children’s progress on the drug. Dr Kewley asserts that all parents of children under his care are told to telephone him about any problems with medication; children are also seen for regular follow-ups.

The heads are worried too about the use of the drug on children under six, which is not recommended by the manufacturers, Ciba-Geigy. “I acknowledge, ” says Dr Kewley, “that Ciba says it’s not licensed for children under six. I only ever use it when I’ve got a major problem. The suggestions are that I am throwing medication at children under six, but that’s not the case at all. I’m using it cautiously, and only in extreme situations.”

Ritalin is classed as a stimulant, along with amphetamines, caffeine and codeine, but is described technically as a “piperidine”. American studies have shown that it has a beneficial effect on at least 80 per cent of ADDADHD children. How can a stimulant help a hyperactive child? Dr David Lott of Ciba explains that Ritalin stimulates a controlling centre in the brain, which he likens to a traffic policeman at a crossroads.

It takes about half an hour to start working, and wears off after about four hours. Common side-effects according to a Harvard study quoted by Dr Tom Brown include headaches, tummy pains, loss of appetite, difficulty in sleeping, and “loss of sparkle”. These tend to be most marked when the child first goes on Ritalin, and the dose is still being adjusted.

There have also been reports in Sussex of severe side-effects, including one child hallucinating when taken off the drug. It is not recommended for any other condition, nor for adults.

While Dr Kewley has not been single-handedly responsible for the rise in the number of children in this country on Ritalin, he has played a significant part in it. Dr Kewley estimates that he has some 500 children under his care on medicines for ADHD or ADD, the great majority on Ritalin. He has become, perhaps unfortunately, the lightning rod for a range of debates which will have wider application if and when (as seems likely) recognition of ADHD becomes more widespread in the UK, and its treatment with medicines grows.

Except in a few mild cases, Ritalin alone will not cure the symptoms of ADHD or ADD. The best claim made for it is that it can put a child into a state of mind where he or she can become more receptive to teaching, counselling and behaviour modification.

Yet the most significant area of concern for West Sussex heads is that they feel insufficiently involved in the treatment process, despite the fact that all the experts and even the drug company agree that drug therapy should only be one element of a broader package of interventions.

And this is perhaps the interesting heart of the debate - the extent to which medical and educational communities are going to be able to work constructively together on ADHD. At present, there is resistance among some teachers to the whole notion of what they see as a behavioural problem being treated along medical lines.

Stan Mould of LADDER puts it succinctly. “Some teachers are fed up with medical people poking their noses into special needs. But ADHDADD is a medical and an educational problem. If your brain isn’t working properly, it’s got to be partly a medical problem.”