Blood-brain barrier P-glycoprotein function is not impaired in early Parkinson's disease

The cause of Parkinson's disease (PD) is unknown. Genetic susceptibility and exposure to environmental toxins contribute to specific neuronal loss in PD. Decreased blood-brain barrier (BBB) P-glycoprotein (P-gp) efflux function has been proposed as a possible causative link between toxin exposure and PD neurodegeneration. In the present study BBB P-gp function was investigated in vivo in 10 early stage PD patients and 8 healthy control subjects using (R)-[(11)C]-verapamil and PET. Cerebral volume of distribution (V(d)) of verapamil was used as measure of P-gp function. Both region of interest (ROI) analysis and voxel analysis using statistical parametric mapping (SPM) were performed to assess regional brain P-gp function. In addition, MDR1 genetic polymorphism was assessed. In the present study, a larger variation in V(d) of (R)-[(11)C]-verapamil was seen in the PD group as compared to the control group. However, decreased BBB P-gp function in early stage PD patients could not be confirmed.