All animals age. However, aging is a heterogeneous process, and individual organisms age differently. Moreover, within the same organism, cells or organs do not age at the same speed. For instance, neurodegeneration, a hallmark of aging, generally manifests later than other peripheral aging signs. The genetic determinants of aging are not completely understood. Gain-of-function (GoF) mutations in leucine-rich repeat kinase 2 (LRRK2^GoF) are major genetic risk factors for Parkinson’s disease (PD). By analyzing PD patients and LRRK2^GoF mice, we show that PD represents an accelerated aging disorder driven by STING-dependent inflammation. This inflammation begins peripherally, disrupts the blood-brain barrier, and causes dopaminergic neurodegeneration. Mechanistically, aging or LRRK2^GoF causes endolysosomal decline, resulting in cytosolic self-DNA accumulation and the release of DNA-containing extracellular vesicles (EVs) that activate the cGAS-STING pathway within and between cells. Our findings identify LRRK2^GoF as a key driver of accelerated aging and systemic inflammaging through DNA-containing EVs, highlighting potential therapeutic targets to counteract inflammaging and neurodegeneration.