Interconnected roles of astrocytes and the blood-brain barrier in Parkinson's disease: pathological evidence, mechanistic insights, and knowledge gaps.

Parkinson's disease (PD) has long been defined by α-synuclein aggregation and dopaminergic neurodegeneration, yet growing evidence indicates that non-neuronal contributors, specifically astrocytes and the blood-brain barrier (BBB), may play key roles in disease progression. Human neuropathological studies reveal BBB disruption and astrocytic abnormalities, including plasma protein extravasation, tight junction alterations, and microvascular degeneration in the substantia nigra and striatum, while neuroimaging and fluid biomarkers such as elevated QAlb, plasma GFAP, and CSF S100B further support