Structural and functional correlates of subthalamic deep brain stimulation-induced apathy in Parkinson’s disease

Notwithstanding the large improvement in motor function in Parkinson’s disease (PD) patients treated with deep brain stimulation (DBS), apathy may increase. Postoperative apathy cannot always be related to a dose reduction of dopaminergic medication and stimulation itself may play a role. We studied whether apathy in DBS-treated PD patients could be a stimulation effect. In 26 PD patients we acquired apathy scores before and >6 months after DBS of the subthalamic nucleus (STN). Magnetoencephalography recordings (ON and OFF stimulation) were performed ≥6 months after DBS placement. Change in apathy severity was correlated with (i) improvement in motor function and dose reduction of dopaminergic medication, (ii) stimulation location (merged MRI and CT-scans) and (iii) stimulation-related changes in functional connectivity of brain regions that have an alleged role in apathy. Average apathy severity significantly increased after DBS (p