Orthostatic hypotension in Parkinson's disease impacts the association between white matter lesion volume and motor symptom burden

ObjectiveTo evaluate whether the presence of orthostatic hypotension (OH) impacts the association between white matter hyperintensity (WMH) volume and motor symptom burden in persons with Parkinsons disease (PWP). MethodsMotor symptom burden in PWP was quantified using the Movement Disorders Society Unified Parkinsons Disease Rating Scale (MDS-UPDRS) Part III. Total WMH volume was segmented based on high-resolution T1-weighted (T1W) and T2 Fluid Attenuated Inversion Recovery (FLAIR) images. Determination of whether individual participants qualified as having OH was based on orthostatic vital signs. All data were obtained from the Parkinsons Progression Markers initiative (PPMI) dataset. ResultsA total of 218 PWP (mean age, 64.84 {+/-} 9.51) and 50 control participants (mean age, 65.52 {+/-} 11.04) were included in the analyses. WMH volume did not differ significantly between the two groups. 15.1% of the participants in the PD group and only 4% of the control group qualified as having OH. Analysis of covariance determined that in PWP, the association between WMH volume and motor symptom burden was significantly different in participants with OH in comparison to those without OH (steeper in the former group). Follow-up analyses suggested that the effects were strongest for bradykinesia symptoms. Adjusting for disease and symptom duration did not alter results. ConclusionsThe presence of OH in PWP impacts the links between white matter lesion volume and motor symptom burden. These findings may provide a potential mechanism underlying the poorer disease prognosis among PWP with OH.