Choroid plexus enlargement contributes to motor severity via regional glymphatic dysfunction in Parkinson's disease.

Choroid plexus (CP) enlargement and glymphatic dysfunction have been implicated in neurodegeneration, but their roles in Parkinson's disease (PD) remain unclear. This retrospective cross-sectional study examined associations among CP volume, perivascular spaces (PVS), and motor symptom severity in 123 PD patients stratified by disease stage. MRI quantified CP volume and PVS, including dilated PVS (dPVS), across brain regions. CP-dPVS correlations were stronger in early-stage PD. Region-specific analyses revealed CP volume was associated with PVS in the midbrain and basal ganglia. CP-dPVS correlations emerged in midbrain, basal ganglia, and centrum semiovale. Correlation matrix and mediation analyses together confirmed that only basal ganglia dPVS was both significantly correlated with motor symptoms and served as a mediator, accounting for 30.52% of the association between CP volume and motor severity. These findings suggest that CP enlargement contributes to motor severity in PD, in part through regional glymphatic dysfunction localized to the basal ganglia.