Ritalin prescriptions for children have increased
Healthy people should be able to take the anti-hyperactivity drug Ritalin to boost brain power, a UK ethicist says.
Bioethics expert Professor John Harris, of the University of Manchester, said if the drug was safe for children, adults should also be able to take it.
Writing on the British Medical Journal website, he said many students were already using the drug - which is illegal without prescription in the UK.
A US expert said there were too many risks for it to be more widely used.
Ritalin, also known as methylphenidate, is given to children with ADHD - attention deficit hyperactivity disorder.
Many doctors say it can help children control their behaviour and perform better at home and school.
If not prescribed, Ritalin is a class B drug in the UK, meaning possession can lead to a five-year prison sentence and dealing could put you behind bars for 14 years.
But there is increasing evidence that healthy adults, especially students, are using it to enhance their mental ability.
Professor Harris said Ritalin's benefits included enhanced study skills and concentration.
He said it was "unethical" to stop healthy people from taking the drug and that there was evidence it was safe to use.
And he added: "Safe always means safe enough and since no drugs are free of side effects, that always means the consumer has judged the risks of adverse effects worth taking, given the probable benefits."
Professor Harris said that if it was safe for children to use Ritalin over a long period of time for a condition that was not usually life-threatening, there was no reason to prevent healthy adults using it too.
He said it was "not rational" to be against human enhancement and likened using drugs to enhance brain power to the use of "synthetic sunlight" - firelight, lamplight and electric light.
"Before synthetic sunshine people slept when it was dark and worked in the light of day.
"With the advent of synthetic sunshine, work and social life could continue into and through the night, creating competitive pressures and incentives for those able or willing to use it to their advantage."
But Professor Anjan Chatterjee, of the University of Pennsylvania, said there were too many risks in taking Ritalin unless a person was actually ill.
He said the US Food and Drug Administration had labelled it with a "black box" - the most alarming of possible warnings - because of its high potential for abuse, dependence, risk of sudden death and serious adverse effects on the heart.
Professor Chatterjee questioned whether children at top schools would take Ritalin in "epidemic proportions" and if people such as pilots, police officers and on-call doctors would be pressurised into taking the drug to perform better.
Again writing in the BMJ, he said: "Endorsing the legal non-therapeutic use of methyphenidate or other cognitive enhancers now is premature.
"The efficacy and risks of enhancers in healthy people needs to be researched adequately and this information needs to be disseminated broadly.
"Until such preparations are made, it is not acceptable to recommend that healthy people take drugs to enhance performance."