OBJECTIVE: Greater educational attainment is a protective factor for neurodegenerative dementias. If education earlier in life leads to greater cerebral reserve, it may play a similar protective role in Parkinson's disease (PD). METHODS: We conducted a cross-sectional clinical imaging study of 142 subjects with PD. All subjects underwent [(11) C]dihydrotetrabenazine PET to confirm nigrostriatal dopaminergic denervation and brain MRI to estimate adjusted cortical gray matter volume (GMV). RESULTS: After adjusting for possible confounders, including cognitive and dopaminergic covariates, as well as nonspecific neurodegeneration covariates (age, disease duration, and total adjusted cortical GMV), lower years of education remained a significant predictor of higher total MDS-UPDRS motor score (t = -3.28; P = 0.001). Education level associated inversely with white matter (WM) hyperintensities in a post-hoc analysis (n = 83). CONCLUSIONS: Higher educational attainment is associated with lower severity of motor impairment in PD. This association may reflect an extranigral protective effect upon WM integrity.