Blood-brain barrier dysfunction and altered choroid plexus contrast kinetics in Parkinson’s disease

Background Neurovascular dysfunction may contribute to Parkinson’s disease (PD), but the extent and clinical relevance of blood-brain barrier alterations remain uncertain. We investigated regional blood-brain barrier permeability, fractional plasma volume, and choroid plexus contrast kinetics in patients with PD using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Methods In this exploratory cross-sectional study, 14 patients with PD and nine age-matched controls underwent 3-T DCE-MRI. The transfer constant (K trans ), fractional plasma volume (v p ), and normalized permeability index (NPI), a measure sensitive to slow contrast accumulation, were quantified in predefined cortical, subcortical, white matter, midbrain, and choroid plexus regions. Group differences and, within the PD group, associations with disease duration, levodopa equivalent daily dose (LEDD), disease severity, motor symptom laterality and Montreal Cognitive Assessment (MoCA) score were assessed. Results Compared with controls, participants with PD demonstrated higher K trans and NPI and lower v p across multiple regions, including the basal ganglia, thalamus, hippocampus, midbrain, cerebral cortex, and white matter. Voxel-wise analyses supported the regional findings, showing increased permeability predominantly in the frontal cortex and widespread reductions in v p . In exploratory within-PD analyses, longer disease duration was associated with higher NPI, whereas higher levodopa equivalent daily dose was associated with lower v p . In an exploratory analysis of seven patients with unilateral onset, NPI was higher in the hemisphere contralateral to the clinically affected body side. Within the PD group, MoCA score was not associated with any imaging parameter, and disease severity showed no association independent of LEDD. In the choroid plexus, PD was associated with higher bilateral K trans , higher left-sided NPI, and lower bilateral v p . Conclusion PD was associated with widespread alterations in DCE-MRI-derived permeability measures and fractional plasma volume. Altered choroid plexus contrast kinetics further suggest involvement of the blood-cerebrospinal fluid interface. Exploratory associations with disease duration, LEDD, and motor laterality support the potential clinical relevance of these imaging abnormalities, and require validation in larger longitudinal cohorts.