In GBA1 carriers, a visuospatial/executive domain score < 4/5 predicted dementia (HR = 4.71, 95% CI = 1.25-17.86, p = 0.022).<h4>Interpretation</h4>GBA1 variant carriers meeting general STN-DBS indication criteria did not show accelerated cognitive decline in the presence of STN-DBS. The gene discussed is GBA1; the disease is Mental deterioration.