Georgiev D, Mencinger M, Rajnar R, et al. - Since several studies have shown that bilateral stimulation of the subthalamic nucleus (STN-DBS) can improve both motor and non-motor symptoms (NMS) in advanced Parkinson disease (PD) patients up to 36 months after surgery, researchers plan to investigate the long-term effect of STN-DBS on NMS in a four-year follow-up, prospective, observational study. Forty patients were recruited and evaluated at baseline. STN-DBS was found to be beneficial in several, but not all, domains of NMS in advanced PD patients for at least 24 months after surgery. Longer follow-up studies on larger cohorts of PD patients are needed to better understand the long-term effect of STN-DBS on NMS.