Attention networks in adults with attention-deficit/hyperactivity disorder (ADHD) and the influence of reward: an fMRI study

Abstract

Attention Deficit Hyperactivity Disorder (ADHD) is a psychiatric disorder which contains inattention, hyperactivity and impulsivity. ADHD has a high prevalence in childhood, but it is also present in adulthood. One cause of ADHD-Symptomatic is a dysfunction in the dopamine-related reward system. Reward increases dopamine releasing. Another theory for ADHD is a lack of behavioral inhibition, which leads to dysfunction in executive functions. Both theories are possible. In studies it could be shown, that brain activity in patience with ADHD is differing to controls.

In this study we analyzed the three attention networks Alerting, Orienting and Executive Control described by Posner in adult patients with ADHD and a sane control group. We used the ANT which was created by Fan et. al. to test these three attention networks. In another step we analyzed the influence of reward on attention and brain activation during the ANT.

For both groups there was an Alerting- Orienting-, and Exectutive-Effect. In the behavioral results the ADHD-group showed the most deficiencies in the Orienting network, which could be compensate by reward. Also in brain activation there were differences in-between the groups, even though they were little and not every expected brain region was activated. An unexpected result in the ANT was the lack of activation differences in the Executive Control network in-between the groups. Reward is leading to a higher Baseline activity and, in particular in the ADHD-group, to activation of reward related dopamine structures. Despite different brain activation in both groups there were rather barely differences in the behavioral results, so that there is the presumption that patience with ADHD activate different, in this study not analyzed, brain regions to achieve the same result as sane controls.