Preoperative Cognitive Profile Predictive of Cognitive Decline after Subthalamic Deep Brain Stimulation in Parkinson's Disease

Cognitive decline represents a severe non-motor symptom of Parkinson’s disease (PD) that can significantly reduce benefits of subthalamic deep brain stimulation (STN DBS). Here, we aimed to identify pre-surgery cognitive profile associated with faster post-surgery cognitive decline in STN DBS treated PD patients to characterize patients who could benefit from more monitoring during treatment course. A retrospective observational study of 126 PD patients treated by STN DBS combined with oral dopaminergic therapy followed for 3.54 years on average (SD = 2.32) with repeated assessments of cognition was conducted. Pre-surgery cognitive profile was obtained via a comprehensive neuropsychological examination. Data were analyzed using exploratory factor analysis for pre-surgery cognitive profile extraction and Bayesian generalized linear mixed models for description of the longitudinal cognitive outcome. Overall, we observed a mild annual cognitive decline of 0.90 points from a total of 144 points in the Mattis Dementia Rating Scale (95% posterior probability interval (PPI) [-1.19, -0.62]). Pre-surgery executive deficit predicted the rate of post-surgery cognitive decline (b = -0.39, 95% PPI [-0.63, -0.15]). The predictive utility of pre-surgery executive deficit resulted from summing small effects of several single test scores. Patients with PD treated with STN DBS experience only mild annual post-surgery cognitive decline. According to our data and models patients with worse long-term cognitive prognosis can be identified via pre-surgery examination of executive functions. Aggregating results from multiple executive tests to estimate cognitive prognosis of PD patients treated with STN DBS is likely superior to examining single test scores.