0694 REM Density in Patients with Idiopathic Parkinson’s Disease with and Without REM Sleep Behavior Disorder

Abstract Introduction Previous studies have reported reduced rapid eye movement density (REM density) in idiopathic Parkinson's disease (PD). It remains unclear how REM density in PD differs between those who have or do not have REM Sleep Behavior Disorder (RBD). The objective of this study was to investigate whether REM density differs in patients with PD with and without RBD. Methods A sample of fourteen patients with PD were enrolled in a cross-sectional study at Virginia Commonwealth University and underwent one-night polysomnography (PSG). Five of fourteen patients had dream enactment behavior and REM sleep without atonia on PSG and were diagnosed with RBD. REM eye movements were visually inspected by two sleep medicine specialists. REM density was defined as the number of rapid eye movements per minute of REM sleep. Mean and standard deviation for the REM density, total sleep time (TST), stage REM (R) percentage and total apnea-hypopneas indices (AHI) were calculated. Two-tailed T-tests were used to compare the means between the two groups. Results For PD without RBD, the mean REM density was 2.3±1.6, mean stage R percentage was 20.1% ±5.5, mean TST was 351.3±72.1 minutes, and mean AHI was 4.1± 4.0. For PD plus RBD, mean REM density was 6.8±1.9 minutes, mean stage R percentage was 20.9% ±9.6, mean TST was 307.6±72.3 minutes, and mean AHI was 1.5 ±3.3. The mean REM density was significantly greater in PD with RBD compared to PD without RBD (P < 0.001). There was no statistical significance of the means of TST, R percentage, and AHI across the two groups. Conclusion Our results show that PD patients with RBD have increased REM density compared to PD patients without RBD, a similar finding to prior studies. Future evaluations and further research open the possibility for REM density as a potential diagnostic biomarker. Support (if any)