The use of prescription drugs designed to treat attention deficit hyperactivity disorder sufferers has soared by more than 50 per cent in six years, new figures have shown.
The amount of prescriptions made for methylphenidate drugs such as Ritalin have been steadily increasing, according to the Care Quality Commission's (CQC) annual report on controlled drugs.
Methylphenidate is considered to be a psychostimulant and is thought to stimulate a part of the brain that changes mental and behavioural reactions.
In 2007, GPs in England wrote 420,000 prescriptions for such medication, but by 2012 the figure had leapt to 657,000 - a rise of 56 per cent.
Officials at the watchdog advised health workers to "carefully monitor" the drugs because they have a potential for "diversion or misuse".
Drugs such as Ritalin are associated with the "smart-drug craze", where students use the medication to improve their concentration when studying and to fight off tiredness.
As many as one in 10 UK students could be taking "cognitive enhancing" drugs such as ritalin, according to research.
The CQC report says the number of prescriptions for such medications rose by 11 per cent between 2011 and 2012.
"As in previous years, we believe that this reflects increased diagnosis of, and prescribing for, the treatment of attention deficit hyperactivity disorder (ADHD)," the CQC report states.
"We are also aware of the possibility that methylphenidate could be diverted and abused, and for this reason we recommend that its use should be monitored carefully.
"We are aware of reports in the media and scientific literature that it is being abused as a 'smart' drug to improve cognitive function; the long-term risks of this practice are not known."
ADHD sufferers often show symptoms such as inattentiveness, hyperactivity and impulsiveness. Behaviour such as this is usually apparent at an early age and it is normally diagnosed between the ages of three and seven.
It is estimated the condition affects 2 per cent to 5 per cent of school-aged children and young people, although it can continue into adulthood.
Additional reporting by PA