WHAT do you do if your son or daughter just can't behave?
If they are so disruptive at school that they are not only ruining their own learning, but other children's as well?
Or if you are a final-year student with a full-time job, desperate to get the grades, but finding yourself exhausted when you come home to study every evening?
For hundreds of thousands of people the answer now is: you take a drug for it.
Last week statistics from the Care Quality Commission revealed a 56 per cent rise since 2007 in prescriptions in England of the stimulant Ritalin.
The drug, chemical name methylphenidate, is licensed for the treatment of attention-deficit hyperactivity disorder (ADHD) in children.
The evidence suggests it is highly effective - children concentrate harder, are calmer and more focused on the drug.
Similar drugs such as atomoxetine or dexamfetamine are also available - but Ritalin is by far the most popular.
Its name will be familiar. In America more than 8 per cent of three to 17-year-olds have been diagnosed with ADHD - and most of them are on medication. It is so all-pervasive across the pond it's already been subject to a cultural backlash.
"I wanna speak louder than Ritalin / For all the children who think that they've got a disease" sang the Dylanesque folk singer Willy Mason, way back in 2004, in a song that voiced a growing concern that, though it might be good for stressed-out parents, the drug could be warping the minds and dulling the spirits of thousands of American children who aren't ill - just rebellious.
The same concerns are now being raised closer to home.
With the number of prescriptions on the NHS rocketing from 420,421 in 2007, to 657,358 in 2012, one of three things must be happening: ADHD is on the rise; we are getting better at spotting it; or, more worryingly, we might be calling people ill who are just, well, naughty.
Writing in The Independent last week, Frank Furedi, professor of sociology at the University of Kent, warned that "society has become increasingly drawn towards using medication as a substitute for authoritative teaching and child-rearing".
He added that he believes that we are going through a "cultural redefinition of some of the normal problems of childhood."
So when does being a naughty become ADHD?
"My definition of an ADHD child is a child that wrecks my consulting room," says Dr Clare Gerada, chair of the Royal College of General Practitioners and a practising GP.
"If a kid is climbing all over the place and pulling things to pieces, then I think, is this ADHD?"
Although GPs do a lot of the prescribing of Ritalin, NICE guidelines are clear that the decision to prescribe in the first place must come from a specialist psychiatrist.
"It's GPs, parents and school teachers that identify the problem and it's for the psychiatrist to diagnose it. We might alert and say, is this ADHD? The consultant psychiatrist will then make the definitive diagnosis," says Dr Gerada.
But does the rise in the number of prescriptions of Ritalin mean that there has been a rise in the number of children behaving in this way, or, as Professor Furedi thinks, has something about our perceptions of that behaviour changed?
"I think we are identifying more and I think we are more ready to prescribe," says Dr Gerada.
"There is always worry that we might be treating naughtiness with medicine. But actually ADHD is a disability that prevents children from learning and it prevents other children from learning.
"Nowadays, 50 per cent of all jobs in the future will require a university degree. Twenty years ago that wasn't the case.
"The need for young people to have a high level of cognitive skill now is immense. I think therefore there is possibly more of a need to manage these children and later adults and it may well be that in the past, certainly as young adults, they might have been tucked away in roles that didn't require concentration.
"In the past you might have ignored it and called it naughtiness, but if those children aren't going to learn and if giving them Ritalin helps them to learn then I know as a parent what I would prefer, albeit knowing that there are problems associated."
The problems with Ritalin and similar drugs are well-known. "We know for a fact that if you give them to children you reduce their growth," says Professor Tim Kendall, a consultant psychiatrist.
"The reason is that the drug stimulates the release of dopamine. Anything that stimulates dopamine has a negative effect on the release of the growth hormone. So you get stunted growth at an average of about three quarters of an inch a year.
"There are a lot of other common side effects we know about. Anxiety states, insomnia, eating problems - to begin with they can't eat at all while they're on them and tend to gorge late at night as the drug wears off.
"A lot of kids, particularly with the long-acting versions of the drug, also find that they get quite depressed."
Another lesser-known problem is that, like alcoholics who find they can no longer socialise without a drink, methylphenidate users can quickly find that they struggle to function when they're not on the drug.
This particular problem has emerged from another, headline-grabbing aspect of the rise of Ritalin and similar drugs - the smart-drugs craze.
Numerous reports exist of students using the drug to get through all-night revision sessions before exams. Methylphenidate and similar drugs are not licensed as mind-enhancers for those without ADHD - the students are getting them from illicit sources.
The Medicines and Healthcare products Regulatory Agency (MHRA) says that the majority of this illicit use is probably fuelled by "drug diversion" - pills prescribed legitimately for ADHD, that find their way into the hands of those who want to give themselves the edge in an exam.
There are also reports of unauthorised websites that sell the drugs for this purpose.
Professor Kendall recounts the stories of patients who were able to get methylphenidate from an Indian website simply by filling in a questionnaire. Methylphenidate is a controlled Class B substance.
Possession without a prescription is illegal and carries the risk of up to five years in prison and up to 14 years for those supplying it.
There is little solid evidence, but students who have tried it invariably report that the drug does indeed improve their concentration. But they are putting themselves at risk of prosecution - and also of dependence.
While the rise in prescriptions may be fuelling a rise in its illicit use, most doctors are beginning to accept that Ritalin's legitimate uses, to treat ADHD, are helping thousands of children.
However, NICE guidelines state, and experts caution, that even where ADHD is diagnosed, clinicians must not be tempted to bypass treatments such as social skills training and behavioural therapy before going "straight to the Ritalin".
"It's a blockbuster drug," says Professor Kendall.
"You see the effect on the kids within half an hour. While they're on it they become much, much calmer, much more focused, they can sit down, they can do some work - there's no doubt it has a beneficial effect in that sense. I spoke to a woman this week whose son had never read before Ritalin.
"He learned to read in a matter of months and not long after that was two years ahead of his reading age. It really, really does work. My only worry is, too it's being used instead of the other things we can do - it's being turned to too quickly."
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