Brain scans of children with attention-deficit/hyperactivity disorder (ADHD) have shown for the first time why people affected by the condition sometimes have difficulty in concentrating.
The study, by experts at The University of Nottingham, may explain why parents often say that their child can maintain concentration when they are doing something that interests them, but struggles with boring tasks.
Using a ‘Whack-a-Mole’ style game, researchers from the Motivation, Inhibition and Development in ADHD Study (MIDAS) group found evidence that children with ADHD require either much greater incentives — or their usual stimulant medication — to focus on a task.
The research, funded by the Wellcome Trust, found that when the incentive was low, the children with ADHD failed to “switch off” brain regions involved in mind-wandering. When the incentive was high, however, or they were taking their medication, their brain activity was indistinguishable from a typically-developing non-ADHD child.
Professor Chris Hollis, in the School of Community Health Sciences, led the study. He said: “The results are exciting because for the first time we are beginning to understand how in children with ADHD incentives and stimulant medication work in a similar way to alter patterns of brain activity and enable them to concentrate and focus better. It also explains why in children with ADHD their performance is often so variable and inconsistent, depending as it does on their interest in a particular task.”
ADHD is the most common mental health disorder in childhood, affecting around one in 50 children in the UK. Children with ADHD are excessively restless, impulsive and distractible, and experience difficulties at home and in school. Although no cure exists for the condition, symptoms can be reduced by medication and/or behavioural therapy. The drug methylphenidate (more often known by the brand name Ritalin) is commonly used to treat the condition.
Previous studies have shown that children with ADHD have difficulty in ‘switching-off’ the default mode network (DMN) in their brains. This network is usually active when we are doing nothing, giving rise to spontaneous thoughts or ‘daydreams’, but is suppressed when we are focused on the task before us. In children with ADHD, however, it is thought that the DMN may be insufficiently suppressed on ‘boring’ tasks that require focused attention.
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