Elliott, Jonathan E.

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.

Aging‐related changes in lung mechanics of human subjects are characterized by a decrease in resistance and an increase in static compliance (decrease in elastic recoil). Together, these changes result in an increase in residual volume in the absence of an increase in total lung capacity. In C57BL/6x129 mice, it was reported that lung compliance increases with aging while elastic recoil pressure does not change. However, in these studies, “old” mice at 24 months of age were compared to “young” mice at 2 months of age, but at this younger age, alveologenesis is incomplete (completion does not occur until ~6 months of age). Accordingly, it remains to be established if the same aging‐related changes in lung mechanics are observed using fully developed adult C57BL/6x129 mice for comparison. To this end, we compared lung mechanics in C57BL/6x129 mice at 6 months (100% survival, n = 6), 18 months (90% survival, n = 6), and 24 months (75% survival, n = 6) of age. Respiratory system static mechanics (Resistance, R rs ; Compliance, C rs ; Elastance, E rs ) were assessed following tracheal intubation using the FlexiVent. There was a progressive aging‐related decrease in R rs (6 month, 0.47 ± 0.02; 18 month, 0.41 ± 0.02; 24 month, 0.35 ± 0.02 cmH 2 O.s/ml), an increase in C rs (6 month, 0.046 ± 0.002; 18 month, 0.052 ± 0.002; 24 month, 0.062 ± 0.002 ml/cmH 2 O), and a decrease in E rs (6 month, 21.73 ± 1.19; 18 month, 19.30 ± 0.87; 24 month, 16.62 ± 1.25 cmH 2 O/ml). Additionally, lungs were fixed following tracheal instillation of 4% paraformaldehyde at 25 cmH 2 O. Thereafter, lungs were dehydrated, paraffin embedded, sectioned (6 μm thick), and stained (hematoxylin and eosin). Using standard stereological approaches, lung sections were analyzed in a uniform systematic but random fashion to assess alveolar morphology (measurement of average distance between alveolar walls based on mean linear intercept, L m ). There was a progressive aging‐related increase in L m (6 month, 34 ± 2; 18 month, 40 ± 2; 24 month, 45 ± 2 μm) consistent with an aging‐related emphysematous‐like change in lung morphometry. Taken together, these results in appropriately aged C57BL/6x129 mice demonstrate an aging‐related change in lung mechanics and morphometry consistent with what is observed in aging humans. Therefore, the results of the present study confirm the use of rodent models for studying aging‐related changes in lung mechanics and morphometry. Support or Funding Information National Institute of Health grants R01‐AG044615 (CBM & GCS) and T32‐HL105355 (JEE).

The risk for respiratory diseases is significantly increased in the elderly population (>65 years of age), which may be partially due to an inability to adequately clear the airways resulting from a progressive aging‐related atrophy and weakening (i.e., sarcopenia) of the diaphragm muscle (DIAm). In humans, reduced maximum inspiratory and transdiaphragmatic pressures suggest DIAm weakening, but muscle fiber atrophy has not been examined. In a National Institute on Aging (NIA) supported mouse model of aging (C57BL/6J strain), we recently showed that DIAm sarcopenia exists and affects non‐ventilatory functions (Greising et al., Exp Gerontol 48:881–887, 2013; Greising et al., Am J Physiol Lung Cell Mol Physiol 309:46–52, 2015). Importantly, rodent models such as this provide a valuable tool to explore the mechanisms underlying DIAm sarcopenia. Currently, the NIA also provides two inbred rat models for aging‐related research: the Fischer 344 (F344) and Brown Norway (BN) rat strains. The purpose of this study was to comprehensively examine whether sarcopenia also exists in the DIAm of F344 and BN rat strains provided by the NIA. Young (6 month, 100% survival) and old (24 month, 50% survival) F344 and young (6 month, 100% survival) and old (32 month, 50% survival) BN male, pathogen free, rats were obtained from the NIA rodent colony. In DIAm strips from the right midcostal region, measurements of contractility, contractile protein concentration, relative myosin heavy chain (MyHC) isoform expression, fiber type distribution and fiber cross‐sectional area (CSA) were obtained. Peak twitch specific force (P t ) was reduced by ~17% and ~14% in the aged F344 and BN rats, respectively. Additionally, maximal specific force (P o ) was reduced by ~24% and ~12% in the aged F344 and BN rats, respectively. Thus, although there was significant aging‐related DIAm weakness in both rat strains, reductions in both P t and P o were more pronounced in old F344 compared to BN rats. In F344 rats, aging also affected DIAm fiber type proportions with a significant increase in the proportion of type I fibers in old (45 ± 3%), compared to young (35 ± 3%) rats, with a concomitant decrease in the relative proportions of both type IIa fibres and type IIx and/or IIb fibers. In BN rats, DIAm fiber type proportions were not affected by aging. In both F344 and BN rats, the CSA of type I and IIa fibers were unchanged, whereas the CSA of type IIx and/or IIb DIAm fibers were reduced by ~20% in F344 rats and by ~15% is BN rats. Similar to DIAm weakness, the selective aging‐related atrophy of type IIx and/or IIb DIAm fibers was more pronounced in F344 rats. In conclusion, DIAm sarcopenia is clearly present in both F344 and BN rat strains, but more pronounced in the F344 strain. These results indicate that in addition to the C57BL/6J mouse model, the F344 rat strain is an appropriate model for research pertaining to DIAm sarcopenia. Support or Funding Information Support: National Institute of Health grants R01‐AG044615 (CBM & GCS) and T32‐HL105355 (JEE).

Abstract Introduction Introduction: Rapid eye movement (REM) sleep behavior disorder (RBD) is strongly associated with progressive phenoconversion to an overt synucleinopathy (e.g., parkinsonism). Neurotrauma [i.e., traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD)], increases the odds of RBD diagnosis by ~2.5-fold and is associated with an increased later diagnosis of Parkinson’s Disease (PD), a service-connected illness in Veterans. Thus, RBD and neurotrauma are both independently associated with parkinsonism; however, it is unclear how neurotrauma influences neurological symptoms and exam findings in patients with RBD. Methods Methods: Participants ≥18 years of age with overnight polysomnogram-confirmed RBD were enrolled between 8/2018 to 4/2021 as part of the North American Prodromal Synucleinopathy (NAPS) Consortium. Standardized assessments for RBD, TBI, and PTSD history, as well as cognitive, motor, sensory and autonomic function were completed. This sub-study applied a cross-sectional, case-control (1:4 ratio) analysis comparing cases (n=24; RBD+TBI+PTSD) to controls (n=96; RBD) matched for age (±2 years), sex, and years of education (±2 years). Results Results: Participants with neurotrauma reported an earlier age of RBD symptom onset and more severe RBD phenotype, more severe anxiety and depression, greater frequency of hypertension, and significantly worse cognitive, motor, and autonomic function compared to participants without neurotrauma. Conclusion Conclusion: This cross-sectional, matched case:control study showed that individuals with comorbid neurotrauma and RBD have significantly worse neurological outcomes related to common features of early parkinsonism. Although confirmatory longitudinal studies are still ongoing, these results may be a sign of further/faster progression of synucleinopathy in those with comorbid neurotrauma and RBD. Support (if any) Support: NIH R34 AG056639, NIH U19 AG071754, VA RRD 1K2 RX002947, Parkinsons Center of Oregon

Abstract Objective Rapid eye movement (REM) sleep behavior disorder (RBD) is widely considered a prodromal synucleinopathy, as most with RBD develop overt synucleinopathy within ~10 years. Accordingly, RBD offers an opportunity to test potential treatments at the earliest stages of synucleinopathy. The North American Prodromal Synucleinopathy (NAPS) Consortium has created a multisite RBD participant, primarily clinic‐based cohort to better understand characteristics at diagnosis, and in future work, identify predictors of phenoconversion, develop synucleinopathy biomarkers, and enable early stage clinical trial enrollment. Methods Participants ≥18 years of age with overnight polysomnogram‐confirmed RBD without Parkinson's disease, dementia, multiple system atrophy, or narcolepsy were enrolled from nine sites across North America (8/2018 to 4/2021). Data collection included family/personal history of RBD and standardized assessments of cognitive, motor, sensory, and autonomic function. Results Outcomes are primarily reported based on sex (361 total: n = 295 male, n = 66 female), and secondarily based on history of antidepressant use ( n = 200 with, n = 154 without; with correction for sex differences) and based on extent of synucleinopathy burden ( n = 56 defined as isolated RBD, n = 305 defined as RBD+ [i.e., exhibiting ≥1 abnormality]). Overall, these participants commonly demonstrated abnormalities in global cognition (MoCA; 38%), motor function (alternate tap test; 48%), sensory (BSIT; 57%), autonomic function (orthostatic hypotension, 38.8%), and anxiety/depression (BAI and PHQ‐9; 39.3% and 31%, respectively). Interpretation These RBD participants, assessed with extensive history, demographic, cognitive, motor, sensory, and autonomic function demonstrated a lack of sex differences and high frequency of concomitant neurological abnormalities. These participants will be valuable for future longitudinal study and neuroprotective clinical trials.

Abstract Introduction Introduction: Rapid Eye Movement (REM) Sleep Behavior Disorder (RBD) is characterized by a lack of muscle atonia during REM sleep with dream enactment. RBD is regarded as a prodromal synucleinopathy as a high proportion of patients eventually phenoconvert to Parkinson’s Disease and related synucleinopathies, suggesting RBD may be an early non-motor symptom of disease. Accordingly, patients with RBD are ideally situated to test potential therapeutic interventions to prevent phenoconversion to synucleinopathy. However, RBD itself, and associated patient registries, are rare. The North American Prodromal Synucleinopathy Consortium (NAPS) establishes a multisite registry of RBD patients with standardized neurological, neuropsychiatric, and neuropsychological assessments and biomarker collection. The present work reports baseline characteristics of this RBD patient database at its current state. Methods Methods: Participants >18 years of age with overnight polysomnogram-confirmed RBD by ICSD-3 criteria who did not meet criteria for the diagnosis of PD, dementia, MSA, or narcolepsy were enrolled from 10 sites across North America (8/2018 to 4/2021). Data collection included family and personal history of RBD and related symptoms, as well as standardized assessments related to cognitive, motor, sensory and autonomic function. Additionally, all subjects have contributed blood, and a subset of subjects have contributed cerebrospinal fluid samples to the National Centralized Repository for Alzheimer's Disease and Related Dementias for future analysis. Results Results: A total of n=251 participants were enrolled. Outcomes are reported based on sex (n=202 male, n=49 female). Data were further examined based on participants’ history of antidepressant use (n=142 with, n=103 without) and based on participants’ extent of synucleinopathy burden (n=70 defined as isolated RBD, n=181 defined as RBD+ [i.e., exhibiting ≥1 abnormality]). Any observed sex differences among the data did not persist after correction for antidepressant use. Conclusion Conclusions: This prospective, cross-sectional data on history, demographic, cognitive, motor, sensory, and autonomic function in n=251 participants with RBD highlight the lack of sex differences and the high preponderance of concomitant neurological abnormalities with RBD, and provide a valuable registry for future longitudinal studies and neuroprotective clinical trials. Support (If Any) NIH NIA R34 AG056639 (YJ, BB)