THOUSANDS of healthy American schoolboys are being dosed on a controversial drug said to improve their performance.

An estimated one in 10 boys aged nine to 13 were being given Ritolin - normally used in the treatment of hyperactivity - so that they would perform better at school or relate better to their parents, said Professor Stephen Rose, director of the Brain and Behaviour Research group at the Open University.

Professor Rose said that ``steroids for the mind'' - smart drugs which would improve cognitive performance in the general population - could be available within the next decade. They will be around initially for the alleviation of conditions like Alzheimer's,'' he said.

``But can we envisage there use spreading until they become as commonly used as steroids for body-builders amd athletes? And if so, what are the ethical, legal, and social consequences?''

Professor Rose said he was concerned at the increasing tendency to blame complex social phenomena - violence and crime in the streets, drug addiction, homelessness - on disordered brains resulting from disordered genes.

``While no one goes so far as to blame violence in Bosnia, Chechnyia, or Rwanda and Burundi on genes responsible for aggression and xenophobia, or suggest its treatment by mass prescription of Prozac, some of the proposals, particularly from the US, tip strongly in that direction.''

But he was less worried about Prozac than the mass dosing of young people with Ritolin.

``Trying to identify biochemical factors in young children leading to antisocial temperament does nothing to address the real causes of the US homicide rate - extremes of poverty and the existence of 280 million handguns said to be in circulation,'' he said.