P 38 Prediction of cognitive outcome of Parkinson's disease patients after subthalamic deep brain stimulation

Abstract

Introduction: Parkinson's disease is a slowly progressive, neurodegenerative disease affecting both motor and non-motor domains. As the disease progresses, cognitive symptoms and dementia become the leading unmet therapeutic need. This is of particular relevance for therapeutic stratification of subthalamic deep brain stimulation which leads to a reliable control of dopaminergic response fluctuations. However, cognitive decline may hamper the therapeutic long-term success. The aim of this retrospective study was to determine preoperative variables that predict cognitive decline in in the long-term after deep brain stimulation. Method: We included 95 patients. MOCA was used to evaluate cognition preoperatively and postoperative in annual intervals. Further patient characteristics were included to the analysis including gender, age at DBS implantation, disease duration at the time of surgery, and motor impairment expressed as UPDRS III. We performed Kaplan-Meier analysis to evaluate the conversion of the preoperative cognitively competent patients (MoCA ≥ 26) to mild cognitive impairment (MoCA <26) or dementia (MoCA < 17). We used Cox-regression to assess the influence of various factors on the probability of occurrence of dementia and MCI in IPS patients. The log-rank test was conducted to compare the statistical survival time. Results: 64.2% of patients developed a MCI, and 12 patients (12.6%) developed dementia after implantation. the percentage of patients who developed MCI 5 years after implantation was estimated at around 56%, 10 years later was this around 72% and 15 years after the operation was estimated at around 90%. In 34 patients no MCI occurred during the course (censored the mean survival time without an MCI was estimated at 6.1 years. After 4.3 years, half of the patients were expected to develop MCI (median survival time). The predictor “age> 70” predicted occurrence of MCI with a hazard ratio of 2.4 ( P =0.0051). “Female gender” was associated with a risk to develop dementia with a hazard ratio of 2.87 (non-significant trend P =0.08). Conclusion: This retrospective analysis suggests that elderly patients are at risk to develop MCI in the 5 years STN-DBS. This may reflect the higher risk of i) disease-related brain pathology and ii) aging. The delayed time course when developing MCI argues more for this combined effect and less for a direct detrimental effect of neuromodulation therapy on cognition.