Disturbed rest-activity rhythm in Parkinson's disease: Associations with motor severity and orthostatic hypotension.

BackgroundThe rest-activity rhythm (RAR) captures the distribution of rest and activity periods between and within days. Disturbed RAR has been observed in Parkinson's disease (PD), but the contribution of motor and non-motor symptoms to RAR disturbances remains unclear.ObjectiveTo evaluate the extent to which motor and non-motor symptoms account for variations in RAR between people with PD (PwPD).Methods464 PwPD and 105 age-matched controls of the ProPark cohort underwent assessment of motor, psychiatric, sleep, and autonomic function. Participants wore a wrist motion sensor for one week to measure RAR, i.e., relative amplitude, interdaily stability, and intradaily variability. Associations between RAR, and demographic and clinical variables were examined using backward stepwise regression models.ResultsPwPD had lower relative amplitude (p < 0.001), lower interdaily stability (p < 0.001), and higher intradaily variability (p < 0.001), than healthy controls. Motor impairment (β=-0.262, 95% CI = [-0.487,-0.125], R²=6.8%) and the presence of orthostatic hypotension (OH) (β=-0.142, 95% CI = [-0.276,-0.026], R²=1.9%) were associated with lower relative amplitude. Motor impairment (β=0.129, 95% CI = [0.005,0.238], R²=2.5%), the presence of OH (β=0.182, 95% CI = [0.079,0.307], R²=3.6%), and higher age (β=0.158, 95% CI = [0.039,0.277], R²=4.0%) were associated with higher intradaily variability, while female gender (β=-0.196, 95% CI = [-0.318,-0.088], R²=4.7%) was associated with lower intradaily variability. Female gender was linked to higher interdaily stability (β=0.205, 95% CI = [0.071,0.321], R²=4.2%).ConclusionsMore severe motor impairment and having OH are associated with RAR disturbances in PwPD. Future studies are needed to evaluate whether optimizing treatment of motor impairment and OH, both symptomatic and asymptomatic, can improve RAR and increase mobility for PwPD.