Effects of Motivation and Medication in ADHD
April 22, 2010 by Leslie E. Packer PhD
Filed under Research
There’s a research article available in full-text online that may be of interest to some parents as it demonstrates that both stimulant medication and enhancing motivation through rewards or consequences contribute to improved response inhibition in children with ADHD.
The study appeared in Biological Psychiatry, 2010 April 1; 67(7): 624–631, and is titled, "Effects of Motivation and Medication on Electrophysiological Markers of Response Inhibition in Children with Attention-Deficit/Hyperactivity Disorder." The authors are: Madeleine J. Groom, Gaia Scerif, Peter F. Liddle, Martin J. Batty, Elizabeth B. Liddle, Katherine L. Roberts, John D. Cahill, Mario Liotti, and Chris Hollis. Here’s the Abstract, but I’ll summarize it afterward:
Background
Theories of attention-deficit/hyperactivity disorder (ADHD) posit either executive deficits and/or alterations in motivational style and reward processing as core to the disorder. Effects of motivational incentives on electrophysiological correlates of inhibitory control and relationships between motivation and stimulant medication have not been explicitly tested.
Methods
Children (9–15 years) with combined-type ADHD (n = 28) and matched typically developing children (CTRL) (n = 28) performed a go/no-go task.Electroencephalogram data were recorded. Amplitude of two event-related potentials, the N2 and P3 (markers of response conflict and attention), were measured. The ADHD children were all stimulant responders tested on and off their usual dose of methylphenidate; CTRLs were never medicated. All children performed the task under three motivational conditions: reward; response cost; and baseline, in which points awarded/deducted for inhibitory performance varied.
Results
There were effects of diagnosis (CTRL > ADHD unmedicated), medication (on > off), and motivation (reward and/or response cost > baseline) on N2 and P3 amplitude, although the N2 diagnosis effect did not reach statistical significance (p = .1). Interactions between motivation and diagnosis/medication were nonsignificant (p > .1).
Conclusions
Motivational incentives increased amplitudes of electrophysiological correlates of response conflict and attention in children with ADHD, towards the baseline (low motivation) amplitudes of control subjects. These results suggest that, on these measures, motivational incentives have similar effects in children with ADHD as typically developing CTRLs and have additive effects with stimulant medication, enhancing stimulus salience and allocation of attentional resources during response inhibition.
You can read the full research report here. If you got lost in the Abstract/technical language, the implications of what they found is that even if a child is on stimulant medication, having consequences such as rewards for response inhibition boosts inhibition. This is particularly relevant when you think about your child’s school program — is the school relying on you placing your child on stimulant medication or are they also incorporating a highly motivating consequence menu?
Wellcome Trust has more about the study, including statements from the researchers:
"When the children were given rewards or penalties, their attention and self-control was much improved," says Dr Maddie Groom, first author of the study. "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 Chris Hollis, who led the study, believes the findings may help to reconcile the often-polarised debate between those who advocate either medication on the one hand, or psychological/behavioural therapy on the other.
"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 affect on the brain," he says. "Both help normalise similar components of brain function and improve performance. What’s more, their effect is additive, meaning they can be more effective when used together."
