In the USA, it has been reckoned that up to one in seven children regularly takes Ritalin, a figure that is so high that even the World Health Organization has urged a more cautious approach. The UK is catching up fast, and its usage had increased by 21 times during the 1990s, and there is no sign of this acceleration slowing today.

If Ritalin is ineffective, doctors may turn to Dexedrine, another amphetamine that is better known by its street name of ‘speed’.

However, the Food and Drug Administration, America’s drug regulator, has instructed manufacturers to indicate on labels for Ritalin and Dexedrine that the drugs may cause “sudden death and serious cardiovascular events”, especially in those who have a history of heart problems.

It has been thought that ADHD results from a genetically-based abnormality in glucose levels and neurotransmitters, and that amphetamines – which usually speed up bodily processes in adults – have a paradoxical effect on children, calming them down and readjusting the chemical imbalance.

But the FDA warning suggests this is not always the case, as the stimulants are raising blood pressure and so increasing the risk of heart problems.

Increasingly, doctors are turning to a new cocktail of drugs. Which may include an antidepressant, a high blood pressure drug and Prozac, along with an amphetamine such as Ritalin.

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