LRRK2 and Mental deterioration: Patients carrying the G2019S variation in leucine-rich repeat kinase-2 (LRRK-2) gene have substantial daily living activities improvement, but results are poorer with the rarer R793M and R1441G variant of this same gene, while homozygous and heterozygous PRKN mutation carriers have good outcomes and minimal cognitive decline up to five years after STN-DBS surgery.