This study is a prospective, single blind parallel trial comparing L-dopa monotherapy and DAs monotherapy after STN DBS. Patients will be enrolled in pairs, with one patient randomly assigned to L-dopa monotherapy and the other to DA monotherapy after STN DBS (20 patients for each study arm). Treatment assignment will be unmasked for the patient but will be blinded for the neurologist programming DBS and evaluating the patient. Another neurologist will be in charge of medication adjustments. Primary outcome is the change in severity of non-motor symptoms as assessed by the Non-motor Symptoms Scale (NMSS) at 3-month follow up visit after surgery.