Herein we describe that LRRK2-mediated phosphorylated Rab12 labels lysosomal structures, GVBs, in LRRK2 mutation carriers and idiopathic PD – and across clinically distinct neurodegenerative diseases (AD, DLB and primary tauopathies) not previously reported to be characterized by LRRK2 pathway dysfunction. Here, LRRK2 is linked to Lewy body dementia.