Increased muscle sympathetic nerve activity and impaired baroreflex control in isolated REM-sleep behavior disorder

Abstract Objective Changes in baroreflex sensitivity have been reported in patients with idiopathic Parkinson’s disease (PD). We sought to investigate the hypothesis that patients with isolated rapid eye movement (REM)-sleep behavior disorder (iRBD), known to be a prodromal stage for PD, will show abnormalities in baroreflex control. Methods Ten iRBD patients were compared to 10 sex- and age-matched healthy controls. Their cardiovascular parameters and muscle sympathetic nerve activity (MSNA) were evaluated at rest and during baroreflex stimulation. Results MSNA at rest was higher in iRBD patients (burst frequency [BF]: 44±3 bursts/min; burst incidence [BI]: 60±8 bursts/100 heartbeats) as compared to the controls (BF: 29±3 bursts/min, p Conclusion Our study shows increased MSNA and impaired baroreflex control in iRBD patients. We propose that the inhibitory effect of locus coeruleus on baroreflex function might be impaired, leading to the disinhibition of sympathetic outflow. Significance These findings might reflect the destruction of brain areas due to the ascending P-α-synuclein deposits in iRBD patients.