GBA1 and Parkinson disease: Secondarily, the risk for conversion to dementia did not differ between PD<sub>GBA1+DBS+</sub> and PD<sub>GBA1+DBS-</sub> (HR = 0.55, 95% CI = 0.23-1.34, p = 0.119) or between PD<sub>GBA1-DBS+</sub> and PD<sub>GBA1-DBS-</sub> (HR = 1.22, 95% CI = 0.53-2.83, p = 0.897).