April 15, 2010
Behavioral Incentives Mimic Effects Of Medication On Brain Systems In ADHD
Medication and behavioral interventions help children with Attention Deficit Hyperactivity Disorder (ADHD) better maintain attention and self control by normalizing activity in the same brain systems, according to researchers at The University of Nottingham.
In a study, funded by the Wellcome Trust and published today in the journal Biological Psychiatry, researchers led by Chris Hollis, Professor of Child and Adolescent Psychiatry, in the School of Community Health Sciences, have shown that medication has the most significant effect on brain function in children with ADHD, this effect can be boosted by complementary use of rewards and incentives which appear to mimic the effects of medication on brain systems.
Professor Chris Hollis said: "Our research may help reconcile the often-polarized debate between those who advocate either medication on the one hand or psychological/behavioral therapy on the other".
ADHD is the most common mental health disorder in childhood, affecting around one in 20 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 a combination of medication and behavior therapy.
Methylphenidate, a drug commonly used to treat ADHD, is believed to increase levels of dopamine in the brain. Dopamine is a chemical messenger associated with attention, learning and the brain's reward and pleasure systems. This change amplifies certain brain signals and can be measured using an electroencephalogram (EEG). Until now it has been unclear how rewards and incentives affect the brain, either with or without the additional use of medication.
To answer these questions, researchers at the University's 'Motivation, Inhibition and Development in ADHD Study' (MIDAS) used EEG to measure brain activity whilst children played a simple game. They compared two particular markers of brain activity that relate to attention and impulsivity and looked at how these were affected by medication and motivational incentives.
The team worked with two groups of children aged nine to 15 years, one group of 28 children with ADHD and a control group of 28 children. The children played a computer game in which green aliens were randomly interspersed with less frequent black aliens, each appearing for a short interval. Their task was to 'catch' as many green aliens as possible, while avoiding catching black aliens. For each slow or missed response, they would lose one point; they would gain one point for each timely response.
In a test designed to study the effect of incentives, the reward for avoiding catching the black alien was increased to five points; a follow-up test replaced this reward with a five point penalty for catching the wrong alien.
The researchers found that when given their usual dose of methylphenidate, children with ADHD performed significantly better at the tasks than when given no medication, with better attention and reduced impulsivity. Their brain activity appeared to normalize, becoming similar to that of the control group.
Similarly, motivational incentives also helped normalize brain activity on the two EEG markers and improved attention and reduced impulsivity, though its effect was much smaller than that of medication.
Dr Maddie Groom, first author of the study, said: "When the children were given rewards or penalties, their attention and self control was much improved. We suspect that both medication and motivational incentives work by making a task more appealing, capturing the child's attention and engaging his or her brain response control systems."
Professor Hollis, said: "Although medication and behavior 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 affect on the brain," he says. "Both help normalize similar components of brain function and improve performance. What's more, their effect is additive, meaning they can be more effective when used together."
The researchers believe that the results lend support from neuroscience to current treatment guidelines for ADHD as set out by the National Institute for Health and Clinical Excellence (NICE). These recommend that behavioral interventions, which have a smaller effect size, are appropriate for moderate ADHD while medication, with its larger effect size, is added for severe ADHD.
Although the findings suggest that a combination of incentives and medication might work most effectively, and potentially enable children to take lower doses of medication, Professor Hollis believes more work is needed before the results can be applied to everyday clinical practice or classroom situations.
"The incentives and rewards in our study were immediate and consistent, but we know that children with ADHD respond disproportionately less well to delayed rewards," he says. "This could mean that in the 'real world' of the classroom or home, the neural effects of behavioral approaches using reinforcement and rewards may be less effective."
Notes to editors: The University of Nottingham is ranked in the UK's Top 10 and the World's Top 100 universities by the Shanghai Jiao Tong (SJTU) and Times Higher (THE) World University Rankings.
More than 90 per cent of research at The University of Nottingham is of international quality, according to RAE 2008, with almost 60 per cent of all research defined as "Ëworld-leading' or "Ëinternationally excellent'. Research Fortnight analysis of RAE 2008 ranks the University 7th in the UK by research power. In 27 subject areas, the University features in the UK Top Ten, with 14 of those in the Top Five.
The University provides innovative and top quality teaching, undertakes world-changing research, and attracts talented staff and students from 150 nations. Described by The Times as Britain's "only truly global university", it has invested continuously in award-winning campuses in the United Kingdom, China and Malaysia. Twice since 2003 its research and teaching academics have won Nobel Prizes. The University has won the Queen's Award for Enterprise in both 2006 (International Trade) and 2007 (Innovation "“ School of Pharmacy), and was named "ËEntrepreneurial University of the Year' at the Times Higher Education Awards 2008.
Nottingham was designated as a Science City in 2005 in recognition of its rich scientific heritage, industrial base and role as a leading research center. Nottingham has since embarked on a wide range of business, property, knowledge transfer and educational initiatives (www.science-city.co.uk) in order to build on its growing reputation as an international center of scientific excellence. The University of Nottingham is a partner in Nottingham: the Science City.
MIDAS Project. For more information about MIDAS, visit www.midas-adhd.org.uk.
The Wellcome Trust. The Wellcome Trust is a global charity dedicated to achieving extraordinary improvements in human and animal health. It supports the brightest minds in biomedical research and the medical humanities. The Trust's breadth of support includes public engagement, education and the application of research to improve health. It is independent of both political and commercial interests.
On the Net: