Videnovic, Aleksandar

Abstract Introduction Patients with Parkinson’s disease commonly underreport sleep symptoms, but the extent to which such mismatch may be present in people with isolated RBD (iRBD) is unknown. We evaluated how the patient–bedpartner (PT–BP) mismatch in night-time and daytime sleep complaints relates to cognition, apathy, dopaminergic degeneration, and cortical structure in iRBD. Methods We retrospectively analyzed 425 iRBD participants (2018–2025) from the North American Prodromal Synucleinopathy (NAPS) Consortium with clinicodemographic data, dopamine transporter (DAT) imaging, and magnetic resonance imaging. Using Scales for Outcomes in Parkinson’s Disease (SCOPA)-Sleep, PT–BP mismatch was classified into overestimator (PT>BP), concordant (PT=BP), and underestimator (PT< BP) groups, separately for complaints during night and day. Outcomes included cognition (CDR-Sum of Boxes [CDR-SB], CDR-global, and individual subdomain tests), pareidolia, apathy, subregional DAT uptake, and cortical thickness. Group differences were tested with analysis of covariance adjusting for age, sex, disease duration, education, clinician-rated OSA treatment inadequacy, and the corresponding patient-reported SCOPA-Sleep domain (night or day), and estimated total intracranial volume for cortical thickness; pairwise tests used Bonferroni correction. Results The PT–BP mismatch was common (night – overestimator 127/425, 29.9% and underestimator 116/425, 27.3%; day – overestimator 77/425, 18.1% and underestimator 134/425, 31.5%). For night-time mismatch, underestimators showed lower CDR-SB and lower CDR-global than overestimators. In addition, underestimators exhibited more illusory responses, fewer correct noise rejections, and fewer total correct responses than overestimator and concordant groups. For daytime mismatch, CDR-SB was lower in underestimators versus overestimators; CDR-global was lower in underestimators and concordant participants versus overestimators. No significant associations were found for apathy. Subregional DAT uptake did not differ by mismatch group. Cortical thickness analyses revealed thinner right transverse gyrus in underestimator and concordant groups compared to the overestimator group and thinner left superior temporal gyrus in underestimator group compared to overestimator group, for night-time mismatch only. Conclusion The PT–BP subjective sleep mismatch can be used as a clinical marker associated with overall cognitive decline and cortical thinning in auditory and language processing areas, which may underlie impairment in perceptual interpretation and hallucination proneness. Further research is warranted to seek longitudinal change and phenoconversion in mismatch groups. Support (if any) #U19-AG071754 (NAPS Consortium)

Abstract Isolated/idiopathic rapid eye movement sleep behavior disorder (iRBD) is a usually prodromal manifestation of neurodegenerative disorders with α-synuclein pathology: Parkinson’s disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). Clinical trials in the iRBD population face substantial barriers: limited access to well-characterized cohorts, inconsistent assessment protocols across centers, and the absence of validated biomarkers of disease burden. The North American Prodromal Synucleinopathy (NAPS) Consortium was established to address these challenges and facilitate clinical trials for neuroprotective therapies targeting synucleinopathy at the earliest known stages. In this multi-site, longitudinal, observational study, nine academic centers across North America will enroll and follow over 500 individuals with iRBD from existing sleep centers. Sixty control participants, matched for age, sex, and race will also be recruited. A harmonized protocol—including a standardized clinical battery assessing motor, cognitive, autonomic, psychiatric, sensory, and sleep function; structured diagnostic adjudication; biospecimen collection; and centralized analysis of both polysomnography and neuroimaging data—is outlined herein and reflects NAPS Stage 2. Each participants completes these assessments annually, and are replaced in the event of phenoconversion. By unifying assessments and expanding geographic reach, NAPS lays the groundwork for efficient, well-powered clinical trials designed to delay or prevent progression of iRBD to overt PD, DLB, or MSA—ultimately enabling earlier, more effective therapeutic intervention for neurodegenerative disease. Registered at clinicaltrials.gov (NCT05826457).

Abstract Study Objectives Rapid eye movement sleep behavior disorder (RBD) is strongly associated with phenoconversion to an overt synucleinopathy, e.g. Parkinson’s disease (PD), Lewy body dementia, and related disorders. Comorbid traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD)—henceforth “neurotrauma” (NT)—increase the odds of RBD by ~2.5-fold and are associated with an increased rate of service-connected PD in Veterans. Thus, RBD and NT are both independently associated with PD; however, it is unclear how NT influences neurological function in patients with RBD. Methods Participants ≥18 years with overnight polysomnogram-confirmed RBD were enrolled between 8/2018 to 4/2021 through the North American Prodromal Synucleinopathy Consortium. Standardized assessments for RBD, TBI, and PTSD history, as well as cognitive, motor, sensory, and autonomic function, were completed. This cross-sectional analysis compared cases (n = 24; RBD + NT) to controls (n = 96; RBD), matched for age (~60 years), sex (15% female), and years of education (~15 years). Results RBD + NT reported earlier RBD symptom onset (37.5 ± 11.9 vs. 52.2 ± 15.1 years of age) and a more severe RBD phenotype. Similarly, RBD + NT reported more severe anxiety and depression, greater frequency of hypertension, and significantly worse cognitive, motor, and autonomic function compared to RBD. No differences in olfaction or color vision were observed. Conclusions This cross-sectional, matched case:control study shows individuals with RBD + NT have significantly worse neurological measures related to common features of an overt synucleinopathy. Confirmatory longitudinal studies are ongoing; however, these results suggest RBD + NT may be associated with more advanced neurological symptoms related to an evolving neurodegenerative process.