We found that LRRK2 is activated in neurodegenerative diseases and associated with tau pathology, evidenced by elevated Rab12 phosphorylation in DLB subjects with high tau pathology and labeling of GVBs as well as mature tau and α-synuclein pathology in tauopathies and synucleinopathies. Here, RAB12 is linked to Lewy body dementia.