GBA1 and Parkinson disease: We expanded on these studies by evaluating longitudinal PD progression, with particular focus on continuous cognitive and motor scores in individuals with LRRK2/GBA PD compared with those with LRRK2 PD, GBA PD, and idiopathic PD (ie, individuals without GBA or LRRK2 variations), and assessing the LRRK2 × GBA gene interaction on cognitive and motor decline.