Predictors of dementia-free survival after bilateral subthalamic deep brain stimulation for Parkinson's disease.

Objective: Bilateral subthalamic nucleus deep brain stimulation (STN DBS) improves motor complications and quality of life (QOL) in patients with Parkinson's disease (PD). However, it does not delay or prevent the occurrence of dementia. The deleterious effects of dementia on QOL and activities of daily living (ADL) underscore the importance of identifying predictors of dementia-free survival in PD patients considered for STN DBS.