The amphetamine drug Ritalin is used to control ADHD behaviour, and prescriptions in the UK have gone up by more than 45 times in the past six years, from 2,000 in 1991 to 92,000 in 1997.
Children with Attention Deficit Hyperactivity Disorder - ADHD - have underactive parts of the brain which deal with decision-making, thinking and planning.
The abnormality was revealed by a magnetic scanning device which enabled researchers to look at the brains of children without harming them from radioactivity.
Eric Taylor, Professor of Child Psychiatry at the Medical Research Council, said this scanning technique had reinforced claims that the controversial disease has a biological cause.
ADHD children find it difficult to concentrate for even short periods. They tend to act on impulse, and often have no sense of danger.
Professor Taylor told the BBC Newsnight programme: "One of their problems is that they find it very hard to stop doing things. They can't wait, they can't delay... you see how the frontal lobes of the brain, the parts involved in decision making and thinking and planning, how they are active and working hard when the decision comes not to respond.
"And we can see for children with hyperactivity, how these frontal parts are underactive. They're not working as they should be."
Drug treatment
The amphetamine drug Ritalin is used to control ADHD behaviour, and prescriptions in the UK have gone up by more than 45 times in the past six years, from 2,000 in 1991 to 92,000 in 1997.
But in the US 3% of children are given the drug, leading some psychiatrists to believe it is given to suppress the child rather than treat the symptoms of ADHD.
Dr Peter Breggin, a psychiatrist, told the programme: "ADHD is a diagnosis that was really developed to justify the drugging of children in American schools... the official diagnosis is a list of things, like a refusal to sit still, a list of behaviours that teachers and to some extent parents would like to control."
Research highlighted on BBC television's Horizon programme earlier this month suggested a link between ADHD and restrictions on children's freedom to play.