ObjectiveTo evaluate whether orthostatic hypotension (OH) or supine hypertension (SH) is associated with brain atrophy and white matter hyperintensities (WMH), we analyzed clinical and radiologic data from a large multicenter consortium of patients with Parkinson disease (PD) and dementia with Lewy bodies (DLB).MethodsSupine and orthostatic blood pressure (BP) and structural MRI data were extracted from patients with PD and DLB evaluated at 8 tertiary-referral centers in the United States, Canada, Italy, and Japan. OH was defined as a systolic/diastolic BP fall ≥20/10 mm Hg within 3 minutes of standing from the supine position (severe ≥30/15 mm Hg) and SH as a BP ≥140/90 mm Hg with normal sitting BP. Diagnosis-, age-, sex-, and disease duration–adjusted differences in global and regional cerebral atrophy and WMH were appraised with validated semiquantitative rating scales.ResultsA total of 384 patients (310 with PD, 74 with DLB) met eligibility criteria, of whom 44.3% (n = 170) had OH, including 24.7% (n = 42) with severe OH and 41.7% (n = 71) with SH. OH was associated with global brain atrophy (p = 0.004) and regional atrophy involving the anterior-temporal (p = 0.001) and mediotemporal (p = 0.001) regions, greater in severe vs nonsevere OH (p = 0.001). The WMH burden was similar in those with and without OH (p = 0.49). SH was not associated with brain atrophy (p = 0.59) or WMH (p = 0.72).ConclusionsOH, but not SH, was associated with cerebral atrophy in Lewy body disorders, with prominent temporal region involvement. Neither OH nor SH was associated with WMH.