Singh, Supriya

Abstract Introduction Rapid eye movement (REM) sleep behavior disorder (RBD) is the single strongest predictor of Parkinson’s disease (PD) risk. Given neurotrauma and psychiatric morbidity, the aging post-9/11 Veteran cohort is a target population for understanding probable RBD frequency and neuroprotection opportunities. We previously reported over 50% of post-9/11 Veterans screened positive for probable RBD. We aimed to examine frequencies of prodromal PD markers and polysomnography (PSG)-confirmed RBD in post-9/11 Veterans. Methods Veterans with probable RBD based on the single-question RBD screen (n=12) were recruited from the Translational Research Center for Traumatic Brain Injury (TBI) and Stress Disorders (TRACTS) Houston cohort. Participants were assessed for subthreshold parkinsonism (Unified Parkinson’s Disease Rating Scale-III Motor score >3, excluding action tremor), olfactory loss (12-item Sniffin’ Sticks), TBI exposures, autonomic symptoms, orthostasis, excessive daytime sleepiness, post-traumatic stress disorder (PTSD), and psychiatric comorbidities. PSG studies were conducted per American Academy of Sleep Medicine guidelines. A board-certified sleep physician confirmed the presence of REM sleep without atonia. We compared the frequency of prodromal marker positivity between participants with and without subthreshold parkinsonism. Results All 12 participants were male (6 [50%] Black, 3 [25%] Hispanic) with a mean (SD) age of 44.4 ± 6.7 years. PSG data (n=10) revealed REM sleep without atonia in 5 (50%), moderate obstructive sleep apnea (OSA) in 2 (20%), and severe OSA in 2 (20%) participants. Five (41.6%) participants had mild motor dysfunction suggestive of subthreshold parkinsonism on the UPDRS-III (M±SD score of 8.6 ± 5.9), while 7 participants had normal or low UPDRS-III ratings (2.3 ± 1.3; p=0.02). Veterans with subthreshold parkinsonism had lower Sniffin’ Sticks scores than those without (M±SD 9.4 ± 2.07 vs. 11.29 ± 0.76; 95% CI: 0.01–3.76, p=0.049). Conclusion This pilot study suggests that motor and olfactory prodromal PD markers are frequent in post-9/11 Veterans with probable RBD. Larger prospective cohort studies are required to further quantify REM sleep without atonia and assess synuclein-specific biomarkers in this population. Support (if any) Center for Alzheimer’s and Neurodegenerative Diseases at Baylor College of Medicine [MJ]; VA CSR&D (#IK2CX002363-01A1) [MJ]; VA RR&D (B9268-X) [RJ]; NIH/NIA/NINDS (U19-AG071754 & R34-AG056639) [ES]; and AASM [ES].