The primary objective of the study is to determine if subthalamic nucleus (STN) deep brain stimulation (DBS) using the Vercise directional leads improves neuropsychiatric state and neuropsychiatric fluctuations 12 months after surgery in a large consecutive series of STN-DBS Parkinson's disease (PD) patients.

This project of further use of health-related data with consent by the participants is a prospective, international project to evaluate the improvement of neuropsychiatric symptoms and the quality of life 12 months after surgery in a large consecutive series of STN-DBS PD patients using novel implantable Neurostimulator Systems (Boston Scientific). The project will investigate if a fine tuning of the STN-DBS settings could alleviate neuropsychiatric fluctuations, apathy as well as DBS-induced dysarthria and global motor state. The tuning is performed in agreement with the instruction for use of all devices used. Further objectives are validation of new tools that are presently entering clinical routine in optimizing postoperative management like individual current sources, steering, imaging of volume of tissue activated, and beta-oscillations.

The data originates from patients suffering from levodopa-responsive PD which are not adequately controlled by dopaminergic medication and therefore receive STN-DBS as a routine standard of care with routinely collected data.

In total 110 patients who are candidates for STN-DBS will be enrolled in four participating sites in Switzerland and the EU.

Inclusion Criteria:

For all subjects:

• Informed consent as documented by signature
• Diagnosis of PD based on the MDS clinical diagnostic criteria for Parkinson's disease
• Fulfilling criteria for STN-DBS:
• The presence of disabling motor complications of dopaminergic treatment
• The absence of surgical contraindications
• Planned bilateral STN-DBS using steering electrodes in the next 3 months (routine standard of care)

Exclusion Criteria:

• Presence of dementia as indicated by a score ≤ 25 on the MOntreal Cognitive Assessment (MOCA)
• Depression with acute suicidal ideation
• Presence of major ongoing psychiatric illness
• Non-compensated systemic disease (i.e., diabetes, hypertension)
• Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc. of the participant
• Participation in interventional trial within the 30 days preceding and during the present study
• Previous enrolment into the current study
• Enrolment of any study site personnel, their family members, employees or other dependent persons

The project population consists of PD patients suffering from levodopa-responsive PD which are not adequately controlled by dopaminergic medication and therefore receive STN-DBS as a routine standard of care.