Abstract
Background: It has been suggested that all patients with Parkinson's disease (PD) who undergo functional neurosurgery have difficulties in slowing down in high conflict tasks. However, it is unclear whether concomitant dopaminergic medication is responsible for this impairment. Objective: To assess perceptual decision making in PD patients with bilateral deep brain stimulation. Methods: We tested 27 PD patients with bilateral deep brain stimulation on a task in which participants had to filter task relevant information from background noise. Thirteen patients were treated with Levodopa monotherapy and 14 patients were treated with Levodopa in combination with a dopamine agonist. Results were compared to healthy matched controls. Results: We found that all PD patients who were treated with a dopamine agonist made faster decisions than controls and PD patients who were not exposed to a dopamine agonist. Further, all patients made more errors than controls, but there was no difference between the two patient groups. Conclusions: Our results suggest that dopamine agonist therapy rather than deep brain stimulation is likely responsible for the inability to slow down in high conflict situations in PD. These results further strengthen the need to reduce dopamine agonists in PD patients undergoing functional neurosurgery in order to prevent them making inadvisable decisions.