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ObjectiveThis study was undertaken to assess cross‐sectional and longitudinal [18F]‐flortaucipir positron emission tomography (PET) uptake in pathologically confirmed frontotemporal lobar degeneration (FTLD) and to compare FTLD to cases with high and low levels of Alzheimer disease (AD) neuropathologic changes (ADNC).MethodsOne hundred forty‐three participants who had completed at least one flortaucipir PET and had autopsy‐confirmed FTLD (n = 52) or high (n = 58) or low ADNC (n = 33) based on Braak neurofibrillary tangle stages 0–IV versus V–VI were included. Flortaucipir standard uptake value ratios (SUVRs) were calculated for 9 regions of interest (ROIs): an FTLD meta‐ROI, midbrain, globus pallidum, an AD meta‐ROI, entorhinal, inferior temporal, orbitofrontal, precentral, and medial parietal. Linear mixed effects models were used to compare mean baseline SUVRs and annual rate of change in SUVR by group. Sensitivity and specificity to distinguish FTLD from high and low ADNC were calculated.ResultsBaseline uptake in the FTLD meta‐ROI, midbrain, and globus pallidus was greater in FTLD than high and low ADNC. No region showed a greater rate of flortaucipir accumulation in FTLD. Baseline uptake in the AD‐related regions and orbitofrontal and precentral cortices was greater in high ADNC, and all showed greater rates of accumulation compared to FTLD. Baseline differences were superior to longitudinal rates in differentiating FTLD from high and low ADNC. A simple baseline metric of midbrain/inferior temporal ratio of flortaucipir uptake provided good to excellent differentiation between FTLD and high and low ADNC (sensitivities/specificities = 94%/95% and 71%/70%).InterpretationThere are cross‐sectional and longitudinal differences in flortaucipir uptake between FTLD and high and low ADNC. However, optimum differentiation between FTLD and ADNC was achieved with baseline uptake rather than longitudinal rates. ANN NEUROL 2022;92:1016–1029

ABSTRACTBackgroundLoss‐of‐function mutations in GRN are a cause of familial frontotemporal dementia, and common variants within the gene have been associated with an increased risk of developing Alzheimer's disease and Parkinson's disease. Although TDP‐43‐positive inclusions are characteristic of GRN‐related neurodegeneration, Lewy body copathology has also been observed in many GRN mutation carriers.ObjectiveThe objective of this study was to assess a Lewy body dementia (LBD) case–control cohort for pathogenic variants in GRN and to test whether there is an enrichment of damaging mutations among patients with LBD.MethodsWe analyzed whole‐genome sequencing data generated for 2591 European‐ancestry LBD cases and 4032 neurologically healthy control subjects to identify disease‐causing mutations in GRN.ResultsWe identified six heterozygous exonic GRN mutations in seven study participants (cases: n = 6; control subjects: n = 1). Each variant was predicted to be pathogenic or likely pathogenic. We found significant enrichment of GRN loss‐of‐function mutations in patients with LBD compared with control subjects (Optimized Sequence Kernel Association Test P = 0.0162). Immunohistochemistry in three definite LBD cases demonstrated Lewy body pathology and TDP‐43‐positive neuronal inclusions.ConclusionsOur findings suggest that deleterious GRN mutations are a rare cause of familial LBD. © 2022 International Parkinson Movement Disorder Society. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Abstract Introduction Accurate, early diagnosis of isolated rapid eye movement (REM) sleep behavior disorder (iRBD) is crucial given its injury potential and neurological prognosis. We aimed to analyze visual and automated REM sleep without atonia (RSWA) diagnostic thresholds in a current cohort of iRBD patients using submentalis (SM) and individual four limb electromyography (EMG) recordings, including bilateral flexor digitorum superificialis (FDS) and anterior tibialis (AT) during polysomnography. Methods We analyzed RSWA in 20 iRBD patients and 20 age-sex-AHI matched controls who underwent polysomnography between 2017-2021 for phasic burst durations, phasic, tonic, and "any" muscle activity, and automated REM atonia index (RAI). Group RSWA metrics were analyzed with non-parametric comparisons, logistic regression, and receiver operating characteristic (ROC) curves to determine optimal diagnostic cutoff thresholds for iRBD. Correlation explored associative relationships between RSWA metrics, and principal components analysis (PCA) defined determinants of RSWA metric variance. Results All mean RSWA metrics were higher in iRBD patients than controls (p<0.05), except for left and bilateral AT phasic density and duration. RSWA(phasic%, AUC; "any"%, AUC) cutoffs were: SM (6.5%, AUC=90.2; 6.5%, AUC=92.5); L FDS (7.3%, AUC=95.8; 7.3%, AUC=95.8%); R FDS (5.4%, AUC=93.5; 5.8%, AUC=93.2%); Bilateral FDS (10.7%, AUC=96; 15.3%, AUC=95.8); L AT (6.7%, AUC=74.5; 6.7%, AUC=74.8%); R AT (4.7%, AUC=76.8; 4.7%, AUC=76.8%); Bilateral AT (7.5%, AUC=77.5; 7.5%, AUC=77.5%), combined SM/FDS (15.0%, AUC=95.5; 15.1%; AUC=95.8), combined SM/AT (16.5%, AUC=85.8; 21.0%; AUC=88.8),tonic (0.5%; AUC=85.9), and RAI (0.90; AUC=91.4). Phasic burst duration cutoffs were: SM=0.7s (AUC=90.2), L FDS=0.5 s (AUC=83.2), R FDS=0.6 (AUC=85.2), L AT=0.3 s (AUC=65.0) and R AT=0.4 s (AUC=77.0). PCA demonstrated that FDS and combined SM/FDS and SM/AT RSWA metrics best explained RSWA variance and differentiated controls from RBD, while SM and AT alone were less explanatory. Conclusion This study provides evidence for quantitative RSWA diagnostic thresholds applicable in current iRBD populations, and confirms the key importance of FDS to assure accurate iRBD diagnosis. Interestingly, these RSWA diagnostic thresholds are lower than previously determined thresholds, suggesting secular trends toward earlier iRBD detection and heterogeneous disease duration relative to polysomnography acquisition, underscoring the necessity of future large scale prospective, multicenter polysomnographic analyses to determine definitive iRBD diagnostic RSWA thresholds. Support (If Any)

Abstract Introduction The objective of this study is to assess the validity of the REM Sleep Behavior Disorder (RBD) symptom severity scale (RBDSSS) and its correlation to the clinical global impression of severity (CGI-S) in a cohort of participants enrolled in the North American Prodromal Synucleinopathy (NAPS) study. RBD is a prodromal marker of α-synucleinopathies with no standardized tool for assessing severity in clinical or research practice. Development of a reliable scale is essential to understand risk of phenoconversion and to monitor response to treatments, particularly in future neuroprotective clinical trials. Methods Participants and their bedpartners enrolled in the NAPS cohort filled out an 8-item questionnaire, developed by the International RBD Study Group, assessing frequency and severity of dreams, vocalizations, movements, and injuries associated with RBD, with higher scores indicating more severe symptoms. The CGI-S is a 7-point scale ranging from normal (1) to most severely ill (7) and was completed by a clinician based on an independent interview with the participant ± their bedpartners. Data was included when patient (RBDSSS-PT) and bedpartner (RBDSSS-BP) responses were both available. Total scores were derived by multiplying assigned point values for frequency and severity (for each question) and summing them for individual RBDSSS-PT scores (total possible=54) and RBDSSS-BP scores (total possible=38). Results This cohort (n=212) included in this analysis was predominantly male (n=175) with a mean ± SE age of 65.16 ± 1.46 years. The median (interquartile range) for RBDSSS-PT, RBDSSS-BP and CGI-S was 11 (4-17), 8 (4-14.3) and 3 (3-4), respectively. Non-parametric Spearman’s rank correlation coefficients (rs) for each variable pair are as follows: RBDSSS-PT vs. RBDSSS-BP, rs=0.575; RBDSSS-PT vs. CGI-S, rs=0.641; RBDSSS-BP vs. CGI-S, rs=0.463 (P<0.0001). Conclusion A moderate correlation was observed between RBDSSS-PT and RBDSSS-BP suggesting good construct validity for the scale. CGI-S correlated moderately with RBDSSS-PT and weakly with RBDSSS-BP. Future, larger studies are needed to explore this as a possible universal and clinically applicable scale for designation of RBD disease burden and prognostication. Support (If Any)

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)

Abstract Introduction REM sleep without atonia (RSWA) is the neurophysiological substrate of REM sleep behavior disorder (RBD), a form of prodromal parkinsonism in most older adults. Isolated RSWA (without clinical RBD) elevation was demonstrated recently in older adults following SARS-CoV2 (COVID-19) infection, but comparison to controls was not reported. We aimed to comparatively analyze RSWA between patients with previous COVID-19 infection and COVID-19 negative controls. Methods 25 patients with previous COVID-19 infection were compared to 25 age-sex matched controls who tested negative for COVID-19 prior to polysomnography. Patients receiving medications known to increase RSWA were excluded. We reviewed medical records to determine clinical features and quantitatively analyzed RSWA in the submentalis (SM) and anterior tibialis (AT) muscles for phasic, tonic, and “any” muscle activity, phasic burst duration, and the automated REM atonia index. Non-parametric analyses compared clinical and polysomnographic features between groups, with combined SM and AT RSWA as the defined primary outcome. The comparative frequency of COVID-19 positive cases and COVID-19 negative controls who met or exceeded proposed isolated RSWA thresholds was also determined. Results COVID-19 patients had significantly greater RSWA than COVID-19 negative controls in the combined SM and AT muscles (p = 0.00076). Most other RSWA metrics were also higher in COVID-19 patients than controls (p<0.03), except tonic muscle activity, phasic burst durations, and RAI. Isolated RSWA occurred more frequently in COVID-19 (9 patients, 36%) than controls (3, 12%; p>0.05). No patients had a clinical history or polysomnographic evidence for parasomnia behavior or a primary neurological condition. Conclusion Quantitative RSWA amounts were comparatively greater in COVID-19 patients than in COVID-19 tested-negative controls, suggesting association of previous COVID-19 infection with central nervous system brainstem dysfunction in the region of the dorsal pons and/or ventromedial medulla. Further prospective studies are needed to determine whether RSWA is a predisposing influence to, or consequence of, COVID-19 infection in these patients, and whether COVID-19 survivors might harbor neurodegenerative risk or disease markers. Support (If Any)

Abstract Introduction Non-REM hypertonia (NRH) was recently reported to be independently associated with the synucleinopathy-mediated neurodegenerative disorders: dementia with Lewy Bodies/Parkinson Disease Dementia (DLB/PDD), Parkinson Disease (PD), and isolated REM sleep behavior disorder (iRBD). In this NRH investigation, we included progressive supranuclear palsy (PSP), a Parkinsonian-spectrum disorder caused by tau pathology. Methods In this multicenter study, patients broadly characterized as presumed Parkinsonian-spectrum disorders (PSD) included DLB/PDD (n=16), PD (n=16), iRBD (n=19), and PSP (n=13). Presumed non-PSD subjects included Alzheimer’s Disease dementia (AD=22), mild cognitive impairment (MCI=35), and normal cognition (NC=61). Sleep Profiler studies were acquired in all participants. NRH, auto-detected based on persistently elevated electromyographic (EMG) power relative to delta, theta, and sigma bands in the differential Af7-Af8 signal, was measured as a percentage of sleep time and then weight-averaged in the 75% of in-home studies with two-nights of data. A >5% threshold characterized abnormal-NRH. Twenty-nine NC were longitudinally retested after 364- to 563-days. Statistical analyses included inter-class correlations (ICC), Bland-Altman plots, multiple logistic regression, and receiver-operating-characteristic curves (ROC). Results In the PSD=41 and non-PSD=95 records with two-nights of data, NRH-severity demonstrated moderate consistency (ICC=0.78, bias=0.6+/-6.2%, P<0.0001). Across the two-nights, NRH was classified consistently as normal or abnormal in 59.6% and 27.2% of the records, vs. normal/abnormal=4.4% or abnormal/normal=8.8%. The test-retest reliability of NRH-severity was good (ICC=0.84, bias=0.06+/-3.8%, P<0.0001), with all retest comparisons repeating as normal (73%) or abnormal (27%). The frequency of abnormal-NRH in PSP=92% was significantly greater than MCI=26%, AD=14%, and NC=16% (all P<0.0001) and PD=56% (P<0.05), but not DLB/PDD=81% and iRBD=74%. Abnormal-NRH was significantly associated with the PSD group (P<0.0001) and it differentiated PSD versus non-PSD group with an area under the curve of 0.78 (95%CI: 0.72-0.85) based on a sensitivity of 0.75 (95%CI: 0.63-0.84) and a specificity of 0.81 (85%CI: 0.73-0.87). Conclusion NRH independently discriminated PSD patients from age-sex similar non-PSD subjects, suggesting that NRH is a common sleep motor signature across clinical PSD phenotypes. We speculate that NRH could be related to pathological changes within the key non-REM sleep motor modulating center in synucleinopathies and PSP. Support (If Any) NIA grants: R44AG050326, R44AG054256, P30AG62677 and R34AG56639.

Abstract Introduction Increased non-REM hypertonia (NRH) and decreased sleep spindle-durations were found to be independently associated with patients broadly characterized as presumed Parkinsonian-spectrum disorder [i.e., dementia with Lewy Bodies/Parkinson Disease Dementia (DLB/PDD), Parkinson Disease (PD), progressive supranuclear palsy (PSP), or isolated REM sleep behavior disorder (iRBD)] when compared to subjects with Alzheimer Disease dementia (AD), mild cognitive impairment (MCI) and normal cognition (NC). In this investigation, the NRH and spindle-duration features were combined to determine whether these biomarkers could distinguish neurodegenerative disorder subtypes. Methods This multicenter investigation included analysis of several neurodegenerative disorder patient subtypes including: DLB/PDD (n=16), PD (n=16), iRBD (n=19), PSP (n=13), AD (n=22), MCI (n=35), and NC (n=61). Sleep Profiler (SP) studies were conducted in all participants. NRH was auto-detected based on persistently elevated electromyographic (EMG) power relative to delta, theta, and sigma bands, while spindles were recognized by temporal excursions in alpha and sigma power > 250-milliseconds. With NRH >5% of sleep-time and spindle-duration <1-minute considered abnormal, tallies were compared across neurodegenerative disorder subtypes with Fisher Exact tests. Results Combined SP features of Normal-NRH/normal-SpD were greater in the NC (56%), AD (46%), and MCI (43%) subtypes versus PSP (8%) and DLB/PDD (6%), and when iRBD (21%) was compared to NC (all P<0.05). Abnormal-NRH/abnormal-SpD were more frequent in PSP (85%) and DLB/PDD (75%) subtypes versus iRBD (26%), PD (25%), MCI (11%), AD (9%), and NC (8%)(all P<0.02). Abnormal-NRH/normal-SpD were greater in iRBD (47%) compared to MCI (14%), NC (8%), PSP (8%), DLB/PDD (6%), and AD (5%) subtypes, and in PD (31%) versus NC (all P<0.05). Normal-NRH/abnormal-SpD occurred more often in AD (41%) than iRBD (5%) and PSP (0%)(both P<0.05). Conclusion The combination of NRH and spindle-duration abnormality occurred more frequently in DLB/PDD and PSP subtypes. Abnormal NRH with normal sleep-duration was more frequent in iRBD and PD subtypes. Normal NRH and spindle-duration occurred most often in NC and MCI types. AD exhibited normal NRH with isolated cases of either normal or abnormal spindle-duration. Our preliminary findings suggest that auto-detected sleep biomarkers may aid in the characterization of neurodegenerative disorder subtypes. Larger prospective cohort studies are needed. Support (If Any) NIA grants: R44AG050326, R44AG054256, P30AG62677 and R34AG56639.

Abstract Introduction Decreased sleep spindle oscillations were previously associated with cognitive decline in older adults, increased tau levels, and phenoconversion to dementia in patients with Parkinson disease (PD). We analyzed quantitative sleep spindle measures to determine if this biomarker was associated with particular neurodegenerative disorder syndromes. Methods Sleep spindle oscillations ascertained in patients broadly characterized as presumed Parkinsonian-spectrum disorders (PSD), which included the subtypes dementia with Lewy Bodies/Parkinson Disease Dementia (DLB/PDD, n=16), PD (n=16), isolated REM sleep behavior disorder (iRBD, n=19), and progressive supranuclear palsy (PSP, n=13), were compared with non-PSD subtypes Alzheimer Disease dementia (AD, n=22), mild cognitive impairment (MCI, n=35), and normal cognition (NC, n=61). Sleep Profiler studies were conducted in all participants. The automated spindle detection algorithms recognized temporal excursions in the alpha (8-12 Hz) and sigma (12-16 Hz) power of 250 milliseconds or greater, with spindle duration being the sum of all spindle elapsed times. Night-to-night variability was assessed in PSP=13, PD=16, DLB/PDD=12, AD=17, MCI=25, and NC=53. Statistical analyses included intraclass correlations (ICC) and Bland-Altman plots for two-night data, and Mann-Whitney U-tests and multiple logistic regression applied to sleep-time weight-averaged spindle-durations. Results The night-to-night spindle-duration ICC was 0.95 (P<0.0001), with a Bland-Altman bias of 0.05+/-2.83 minutes. Spindle-duration was independently associated with PSD versus non-PSD groups (P=0.017, OR 1.08, 95%-CI 1.01-1.15), but not significantly associated with age (P=0.12, OR 1.03, 95%-CI 0.99-1.07) or sex (P=0.54). When stratified by subtype, age was associated with spindle-duration when NC were compared to AD and MCI (P=0.0003, OR 1.10, 95%-CI 1.04-1.16) and when iRBD were compared to DLB/PDD, PD and PSP (P<0.05, OR 1.00, 95%-CI 0.89-1.13)Spindle-durations were reduced in PSP (0.9+/-2.1) and DLB/PDD (2.0+/-5.1) when individually compared to AD (3.2+/-7.1), iRBD (3.3+/-3.4), PD (5.3+/-6.6), MCI (5.3+/-9.7), and NC (8.0+/-11.1) subtypes (all P<0.05). AD patients also exhibited lower spindle-durations than NC (P=0.03). Conclusion Auto-detected sleep spindle-durations exhibited excellent night-to-night reliability in both NC and patients with neurologic disorders. Decreased sleep spindle-duration was independently associated with PSP and DLB/PDD, and in AD. Reduced sleep spindle duration may be a distinct sleep biomarker for those disorders likely indicating thalamocortical dysfunction. Support (If Any) NIA grants: R44AG050326, R44AG054256, P30AG62677 and R34AG56639.