Inclusion Criteria:  Age between 35 and 80 yrs. Ability to communicate with the study physician and to understand the requirements of the study Idiopathic Parkinson's Syndrome; IPS (according to MDS-Criteria) Implantation of a DBS device for the stimulation of the subthalamic nucleus (STN) to treat PD.  Exclusion Criteria:  Any inability to communicate with the study physician and to understand the requirements of the study Exclusion criteria of an idiopathic Parkinson's syndrome (IPS) Fulfills the criteria of dementia (according to the International Classification of Diseases (ICD) 10)