Subthalamic Stimulation Improves Quality of Sleep in Parkinson Disease: A 36-Month Controlled Study

Background: Sleep disturbances and neuropsychiatric symptoms are some of the most common nonmotor symptoms in Parkinson’s disease (PD). The effect of subthalamic stimulation (STN-DBS) on these symptoms beyond a short-term follow-up is unclear. Objective: To examine 36-month effects of bilateral STN-DBS on quality of sleep, depression, anxiety, and quality of life (QoL) compared to standard-of-care medical therapy (MED) in PD. Methods: In this prospective, controlled, observational, propensity score matched, international multicenter study, we assessed sleep disturbances using the PDSleep Scale-1 (PDSS), QoL employing the PDQuestionnaire-8 (PDQ-8), motor disorder with the Scales for Outcomes in PD (SCOPA), anxiety and depression with the Hospital Anxiety and Depression Scale (HADS), and dopaminergic medication requirements (LEDD). Within-group longitudinal outcome changes were tested using Wilcoxon signed-rank and between-group longitudinal differences of change scores with Mann-Whitney U tests. Spearman correlations analyzed the relationships of outcome parameter changes at follow-up. Results: Propensity score matching applied on 159 patients (STN-DBS n = 75, MED n = 84) resulted in 40 patients in each treatment group. At 36-month follow-up, STN-DBS led to significantly better PDSS and PDQ-8 change scores, which were significantly correlated. We observed no significant effects for HADS and no significant correlations between change scores in PDSS, HADS, and LEDD. Conclusions: We report Class IIb evidence of beneficial effects of STN-DBS on quality of sleep at 36-month follow-up, which were associated with QoL improvement independent of depression and dopaminergic medication. Our study highlights the importance of sleep for assessments of DBS outcomes.