New research led by QIMR Berghofer Medical Research Institute in Queensland has identified ways to prevent neuropsychiatric side-effects of subthalamic deep brain stimulation (DBS) for Parkinson disease.
A team led by neuropsychiatrist Dr Philip Mosley used a virtual casino to assess impulsive behaviour in 55 patients with Parkinson disease before and after undergoing subthalamic deep brain stimulation.
They found that greater connectivity of the stimulation site with frontostriatal networks was related to greater postoperative impulsiveness and disinhibition as assessed by the neuropsychiatric instruments.
Patients who placed larger bet sizes in the virtual casino postoperatively had greater connectivity of the stimulation site with right and left orbitofrontal cortex, right ventromedial prefrontal cortex and left ventral striatum.
However the connectivity of reward evaluation and response inhibition networks prior to the procedure was not associated with postoperative impulsivity.
“This suggests that the site and distribution of stimulation is a more important determinant of postoperative neuropsychiatric outcomes than preoperative brain structure and that stimulation acts to mediate impulsivity through differential recruitment of frontostriatal networks,” the researchers report in the journal Brain.
A notable finding was that it was possible to identify patients with clinically-significant, harmful changes in mood and behaviour attributable to DBS, based upon an analysis of connectivity and its relationship with gambling behaviour.