Stimulant drugs, such as Ritalin, are given to some children with ADHD
The brains of children with attention-deficit disorders respond to on-the-spot rewards in the same way as they do to medication, say scientists.
A Nottingham University team measured brain activity as children played a computer game, offering extra points for less impulsive behaviour.
Their findings, published in Biological Psychiatry, could mean lower doses of drugs such as Ritalin in severe cases.
But they warn teachers and parents may often struggle to give instant rewards.
Estimates vary, but it is believed that up to 5% of children in the UK have some form of attention-deficit hyperactivity disorder (ADHD).
This can lead to behavioural problems including impulsive actions, fidgeting and poor attention span, and can affect a child's academic and social progress.
In severe cases, stimulant drugs such as Ritalin, which act on parts of the brain associated with attention and behaviour, can be given.
In addition, parents are often asked to try to influence the child's actions directly by rewarding positive behaviour and making sure that there are negative consequences if a child behaves badly.
Research has suggested that, unlike in non-ADHD children, these incentives and disincentives only work well if delivered on the spot, as opposed to later in the day or week.
The Nottingham team wanted to look at the effects of this "behaviour therapy" in the brain of the child.
They devised a computer game in which children had to "catch" aliens of a certain colour, while avoiding aliens of a different colour.
The game was designed to test the children's ability to resist the impulse to grab the wrong sort of alien.
To test whether incentives made a difference, in one variant of the game the reward for catching the right alien was increased fivefold, as was the penalty for catching the wrong one.
Activity in different parts of the brain was monitored using an electroencephalogram (EEG).
They found that the incentives helped the children perform better at the game, although not to the same extent as the child's normal dose of Ritalin.
However, the EEG revealed that both were "normalising" brain activity in the same regions.
Professor Chris Hollis, who led the research, said that the combination of drugs and incentives produced the best results, and might mean children with ADHD could take lower doses of drugs while maintaining control of their behaviour.
He said: "Although medication and behaviour therapy appear to be two very different approaches of treating ADHD, our study suggests that both types of intervention may have much in common in terms of their effect on the brain.
"Both help normalise similar components of brain function and improve performance."
However, he conceded that it might not always be practical to use behavioural therapy.
"We know that children with ADHD respond disproportionately less well to delayed rewards - this could mean that in the 'real world' of the classroom or home, the neural effects of behavioural approaches using reinforcement and rewards may be less effective."
Andrea Bilbow, from the National Attention Deficit Disorder Information and Support Service (Addiss), echoed this: "It means you have to be in front of that child 24/7, and you just can't do that - teachers and schools would have to totally change the way they deal with this."