The extent to which comorbid cerebrovascular disease (CVD) and other structural and physiological neurovascular changes are relevant to idiopathic Parkinson's disease, including its pathophysiology, clinical course, and response to treatment, is not well defined. We are investigating this using novel MRI techniques, including arterial spin labelling (ASL), and our findings include prolongation of arterial arrival time as well as greater burden of structural markers of CVD in patients with IPD, with some suggestion of differences between IPD clinical phenotypes.