The relevance of impaired neurovascular function in idiopathic Parkinson's disease (IPD) is unknown. Furthermore, it is unknown whether any such changes might contribute to, or be the effect of, neurodegeneration, or potentially reflect comorbid cerebrovascular disease (CVD). MRI arterial spin labelling (ASL) is a suitable, non-invasive tool for quantifying cerebral haemodynamics including measurements of cerebral blood flow (CBF) and arterial arrival time (AAT). Prolonged AAT has been attributed to increased collateral circulation, chronic vasodilatation and/or increased tortuosity of vessels.

12 subjects with CVD (mean age 68.9±7.8), 19 tremor dominant (TD) IPD subjects (mean age 67.2±0.6), 17 postural instability and gait dominant (PIGD) IPD subjects (mean age 70.7±6.6) and 23 control subjects (mean age 65.1±5.7) completed a 3T MRI scanning protocol, including ASL. CVD subjects had significantly more cerebrovascular risk factors than the other groups. A significant widespread increase in baseline AAT was seen in IPD (both TD and PIGD) and CVD groups when compared to controls. Voxel-based analysis of CBF revealed significant focal hypoperfusion (predominantly posteriorly) in the TD, PIGD and the CVD groups when compared to controls.

These novel findings suggesting similar alterations in cerebral haemodynamics in IPD and CVD groups merit further study.