As many as one in 10 children are thought to be affected by the disorder, which includes an inability to pay attention, restlessness, boundless energy and inquisitiveness. Boys are six to nine times more likely to have ADHD than girls, possibly because of differences as the foetal brain grows.
Results of the test, developed at the centre for applied neurosciences at Swinburne University of Technology, appear to confirm that the disorder is rooted in the brain's biology. The test, known as steady state probe topography, has uncovered significant differences in activity in the frontal lobe of the brains of boys with ADHD, compared with "normal" boys.
The children were given visual exercises that required them to respond in a certain way when the letter X appeared on a screen, with the letter A showing shortly beforehand to warn them.
The frontal lobes of the brains in children without the disorder were activated by the exercise, but not those of the ADHD children. According to researchers, if these parts of the brain are not properly active, children tend to be more easily distracted.
Scientists have considered it paradoxical that some children with ADHD have been given brain-stimulating drugs, even though they appear to be highly stimulated anyway. Now, the Swinburne research suggests that this may be the correct treatment.
The test will now be used in the treatment regimes of ADHD children in an attempt to determine the optimum drug dosage.