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While a growing body of studies suggests a link between sleep disturbances and neurodegenerative diseases’ (NDDs) development, prior studies have been hindered by small sample sizes, short follow-up times and a lack of objective sleep measures.In this cohort study, patients who underwent polysomnography (PSG) at the Innsbruck Sleep Disorders Unit from January 2004 to December 2007, aged ≥18 years, without NDDs at baseline or within five years post PSG, and with at least five years clinical follow-up were included. The main outcome measure was NDDs diagnosis at least five years after polysomnography, assessed until December 2021.Of 1454 patients assessed for eligibility, 999 (68.7%) met inclusion criteria (683 (68.3%) men; median age 54.9 (interquartile range, IQR 33.9-62.7) years. Seventy-five patients (7.5%) developed NDDs, 924 (92.5%) remained disease-free after 12.8 (IQR 9.9-14.6) years median follow-up. After adjusting for demographic, sleep, and clinical covariates, each percent decrease in sleep efficiency, N3 sleep, or REM sleep was associated with 1.9%, 6.5%, and 5.2% increased risk of incident NDDs (hazard ratio, HR, 1.019, CI:1.002-1.035; HR 1.065, CI:1.007-1.118; HR 1.052, CI:1.012-1.085,), respectively whereas one percent decrease in night-time wakefulness represented a 2.2% reduced risk (HR 0.978, CI:0.958-0.997). Random forest analysis identified wake, followed by N3 and REM sleep percentages, as the most important feature associated with NDDs development. Additionally, multiple sleep features combination offered more robust discrimination of incident NDDs compared to single sleep stages.These findings support contribution of sleep architecture changes to NDDs pathogenesis and provide insights into the temporal window during which these changes are detectable, pointing to sleep as early NDDs marker and potential target of neuroprotective strategies.

BackgroundParkinson’s Disease (PD) has been associated with a distinct odour, strongest in sebum-rich areas. Thermal Desorption – Gas Chromatography – Mass Spectrometry (TD-GC-MS) has revealed volatile signatures that distinguish individuals with Parkinson’s Disease (PD) from healthy controls. Here, we applied the same method, including subjects with isolated REM sleep behaviour disorder (iRBD) to examine the volatiles in sebum and compare this with that found in PD subjects and control participants. Participants with iRBD have a high likelihood for conversion to overt clinical synucleinopathies like PD, Dementia with Lewy Bodies (DLB) or (less commonly) Multiple System Atrophy (MSA).MethodsSubjects with clinically established PD (n=16) or iRBD (n=9) as well as healthy controls (n=9) were included. Following methods established in our laboratory, sebum was sampled from each participant using cotton gauze and the headspace from these swabs, analysed directly with TD-GC-MS1,2. Univariate and multivariate analysis was employed to probe the differences between volatile metabolites found for each phenotype. Putative identifications were assigned using spectral matching against the Golm metabolome and NIST spectral databases.FindingsWe can completely classify each phenotype using the sampled volatilome from which we built models with logistic regression analysis. The classification between PD and control improved on previously published work, from 85% to 100%. Putatively annotated molecules include alkanes, aldehydes, fatty acid methyl esters (FAMEs), and three metabolites namely purine, tropinone and oleamide. Investigation of highly ranked features revealed 18 features that showed intermediate expression in samples from iRBD participants.InterpretationTD-GC-MS can differentiate volatile metabolite signatures from sebum between PD, RDB and control samples. More than 70% of the identifiable metabolites that permit this discrimination were putatively annotated as hydrocarbons and fatty acid methyl esters (FAMEs). Our prior work indicates that these components arise from larger lipid molecules that decompose during the experiment2. Features putatively annotated as tropinone, oleamide and purine, have previously been linked with neuroprotection, sleep induction and antioxidation, respectively, are significantly different between the three groups of participants, along with FAMEs and hydrocarbons.FundingWe thank Michael J Fox Foundation (grant ref:12921) and Parkinson’s UK (grant ref: K-1504) for funding this study and Community of Analytical and Measurement Sciences (CAMS) for supporting DT’s research position. This work was supported by the BBSRC (award BB/L015048/1) for instrumentation used in this work and by a DTA to CW-D (project ref. 2113640). We also thank our recruitment centres for their enthusiasm and rigor during the recruitment process. We are very grateful to all the participants who took part in this study as well as PIs and nurses at the recruiting centres.

Rapid eye movement (REM) sleep behavior disorder (RBD), enactment of dreams during REM sleep, is an early clinical symptom of alpha-synucleinopathies. RBD also defines more severe forms of alpha-synucleinopathies. The genetic background of RBD and its underlying mechanisms are not well understood. Here, we performed the first genome-wide association study of RBD, identifying five RBD risk loci. Expression analyses highlight SNCA-AS1 and SCARB2 differential expression in different brain regions in RBD, with SNCA-AS1 further supported by colocalization analyses. Genetic risk score and other analyses provide further insights into RBD genetics, highlighting RBD as a unique subpopulation that will allow future early intervention.

PSAP encodes saposin C, the co-activator of glucocerebrosidase, encoded by GBA. Since GBA mutations are associated with idiopathic/isolated REM sleep behavior disorder (iRBD), a prodromal stage of synucleinopathy, we examined the role of PSAP mutations in iRBD. We fully sequenced PSAP and performed Optimized Sequence Kernel Association Test in 1,113 iRBD patients and 2,324 controls. We identified loss-of-function (LoF) mutations, which are very rare in PSAP, in three iRBD patients and none in controls (uncorrected p=0.018). Two variants were stop mutations, p.Gln260Ter p.Glu166Ter, and one was an in-frame deletion, p.332_333del. All three mutations have a deleterious effect on saposin C, based on in silico analysis. In addition, the two carriers of p.Glu166Ter and p.332_333del mutations also carried a GBA variant, p.Arg349Ter and p.Glu326Lys, respectively. The co-occurrence of these extremely rare PSAP LoF mutations in two (0.2%) GBA variant carriers in the iRBD cohort, is unlikely to occur by chance (estimated co-occurrence in the general population based on gnomAD data is 0.00035%). Although none of the three iRBD patients with PSAP LoF mutations have phenoconverted to an overt synucleinopathy at their last follow-up, all manifested initial signs suggestive of motor dysfunction, two were diagnosed with mild cognitive impairment and all showed prodromal clinical markers other than RBD. Their probability of prodromal PD, according to the Movement Disorder Society research criteria was 98% or more. These results suggest a possible role of PSAP variants in iRBD and potential genetic interaction with GBA, which requires additional studies.

Kleine-Levin Syndrome (KLS) is a rare disorder characterized by severe episodic hypersomnia, with cognitive impairment accompanied by apathy or disinhibition. Pathophysiology is unknown, although imaging studies indicate decreased activity in hypothalamic/thalamic areas during episodes. Familial occurrence is increased, and risk is associated with reports of a difficult birth. We conducted a worldwide case-control genome wide association study in 673 KLS cases collected over 14 years, and ethnically matched 15,341 control individuals. We found a strong genome-wide significant association (OR=1.48,rs71947865,p=8.6×10−9) with 20 single nucleotide polymorphisms encompassing a 35kb region located in the 3’ region ofTRANK1gene, previously associated with bipolar disorder and schizophrenia. Strikingly, KLS cases withTRANK1rs71947865 variant had significantly increased reports of a difficult birth. As perinatal outcomes have dramatically improved over the last 40 years, we further stratified our sample by birth years and found that recent cases had a significantly reducedTRANK1rs71947865 association. While theTRANK1rs71947865 association did not replicate in the entire follow-up sample of 171 KLS cases, the TRANK1 rs71947865 was significantly associated with KLS in the subset follow-up sample of 59 KLS cases who reported birth difficulties (OR=1.54;p=0.01). Genetic liability of KLS as explained by polygenic risk scores was increased (pseudo r2=0.15;p−22at p=0.5 threshold) in the follow-up sample. Pathway analysis of genetic associations identified enrichment of circadian regulation pathway genes in KLS cases. Our results suggest links between KLS, behavioral rhythmicity, and bipolar disorder, and indicates that theTRANK1polymorphisms in conjunction with reported birth difficulties may predispose to KLS.Significance StatementGenetic markers inTRANK1gene and its vicinity have been weakly associated with bipolar disorder and schizophrenia (10% increased risk). We found that the same polymorphisms are associated with Kleine-Levin Syndrome (50% increased risk), a rare sleep disorder characterized by recurrent episodes of severe hypersomnia and cognitive abnormalities. Response to lithium treatment are suggestive of a pathophysiological overlap between KLS and bipolar disorder. The study also shows that variants in theTRANK1gene region may predispose to KLS when patients have had a difficult birth, suggesting thatTRANK1gene region modulate newborns’ response to brain injury, with consequences for mental and neurological health in adulthood. Another possibility may be that the polymorphism impact birth and KLS.

Isolated REM sleep behaviour disorder is an early-stage α-synucleinopathy in most, if not all, affected subjects. Detection of pathological alpha-synuclein in peripheral tissues of isolated REM sleep behaviour disorder patients may identify those progressing to Parkinson’s disease, dementia with Lewy bodies or multiple system atrophy, with the ultimate goal of testing preventive therapies. Real-Time Quaking-Induced Conversion provided evidence of α-synuclein seeding activity in cerebrospinal fluid and olfactory mucosa of patients with α-synucleinopathies. Aim of this study was to explore Real-Time Quaking-Induced Conversion detection of α-synuclein aggregates in olfactory mucosa of large cohort of subjects with isolated REM sleep behavior disorder compared to Parkinson’s disease and controls.This prospective bicentric case-control study was performed between October 2017 and December 2018 at the Medical University of Innsbruck, Austria, and the Hospital Clinic de Barcelona, Spain. Olfactory mucosa samples obtained by nasal swab in 63 patients with isolated REM sleep behavior disorder, 31 matched Parkinson’s disease patients and 59 matched controls were analysed by α-synuclein Real-Time Quaking-Induced Conversion in a blinded fashion at the University of Verona, Italy. Median age of isolated REM sleep behavior disorder patients was 70 years, 85.7% were male. All participants were tested for smell, autonomic, cognitive and motor functions.Olfactory mucosa was α-synuclein Real-Time Quaking-Induced Conversion positive in 44.4% isolated REM sleep behavior disorder patients, 41.9% Parkinson’s disease and 10.2% controls. While the sensitivity for isolated REM sleep behavior disorder plus Parkinson’s disease versus controls was 40.9%, specificity was high (89.8%). Among isolated REM sleep behavior disorder patients with positive α-synuclein Real-Time Quaking-Induced Conversion, 78.6% had olfactory dysfunction as compared to 21.4% with negative α-synuclein Real-Time Quaking-Induced Conversion, pReal-Time Quaking-Induced Conversion olfactory mucosa isolated REM sleep behavior disorder patients (pWe provide evidence that α-synuclein Real-Time Quaking-Induced Conversion assay enables the molecular detection of neuronal α-synuclein aggregates in olfactory mucosa of patients with isolated REM sleep behavior disorder and Parkinson’s disease. Although the overall sensitivity was moderate in this study, nasal swabbing is attractive as simple, non-invasive test, with a potential of use as screening test to identify subjects in the prodromal stages of α-synucleinopathies. Further studies are needed to enhance sensitivity, and better understand the temporal dynamics of α-synuclein seeding in the olfactory mucosa and spreading to other brain areas during the progression from isolated REM sleep behavior disorder to overt α-synucleinopathy.

Isolated rapid-eye-movement (REM) sleep behavior disorder (iRBD) is a parasomnia, characterized by loss of muscle atonia and dream enactment occurring during REM sleep phase. Since a large subgroup of iRBD patients will convert to Parkinson’s disease, and since previous genetic studies have suggested common genes, it is likely that there is at least a partial overlap between iRBD and Parkinson’s disease genetics. To further examine this potential overlap and to identify genes specifically involved in iRBD, we fully sequenced 25 genes previously identified in genome-wide association studies of Parkinson’s disease. The genes were captured and sequenced using targeted next-generation sequencing in a total of 1,039 iRBD patients and 1,852 controls of European ancestry. The role of rare heterozygous variants in these genes was examined using burden tests and optimized sequence Kernel association tests (SKAT-O), adjusted for age and sex. The contribution of biallelic (homozygous and compound heterozygous) variants was further tested in all genes. To examine the association of common variants in the target genes, we used logistic regression adjusted for age and sex. We found a significant association between rare heterozygous nonsynonymous variants in BST1 and iRBD (p=0.0003 at coverage >50X and 0.0004 at >30X), mainly driven by three nonsynonymous variants (p.V85M, p.I101V and p.V272M) found in a total of 22 (1.2%) controls vs. two (0.2%) patients. Rare non-coding heterozygous variants in LAMP3 were also found to be associated with reduced iRBD risk (p=0.0006 at >30X). We found no statistically significant association between rare heterozygous variants in the rest of genes and risk of iRBD. Several carriers of biallelic variants were identified, yet there was no overrepresentation in iRBD patients vs. controls. To examine the potential impact of the rare nonsynonymous BST1 variants on the protein structure, we performed in silico structural analysis. All three variants seem to be loss-of-function variants significantly affecting the protein structure and stability. Our results suggest that rare coding variants in BST1 and rare non-coding variants in LAMP3 are associated with iRBD, and additional studies are required to replicate these results and examine whether loss-of-function of BST1 could be a therapeutic target.

ObjectiveTo examine the role of autosomal dominant (AD) and recessive (AR) Parkinsonism genes in the risk of isolated rapid-eye-movement (REM) sleep behavior disorder (iRBD).MethodsTen genes implicated in AD and AR Parkinsonism were fully sequenced using targeted next-generation sequencing in 1,039 iRBD patients and 1,852 controls of European ancestry. These include the AR genes PRKN, DJ-1 (PARK7), PINK1, VPS13C, ATP13A2, FBXO7 and PLA2G6, and the AD genes LRRK2, GCH1 and VPS35. To examine the role of rare heterozygous variants in these genes, burden test and SKAT-O analyses were performed. The contribution of homozygous and compound heterozygous variants was further examined in the AR genes. Copy number variants (CNVs) in PRKN were tested in a subset of samples (n=374) using multiplex ligation-dependent probe amplification followed by analysis of all samples using ExomeDepth.ResultsWe found no association between rare heterozygous variants in the tested genes and risk for iRBD. Several homozygous and compound heterozygous carriers were identified with variants of unknown significance, yet there was no overrepresentation in iRBD patients versus controls.ConclusionOur results do not support a major role for variants in PRKN, PARK7, PINK1, VPS13C, ATP13A2, FBXO7, PLA2G6, LRRK2, GCH1 and VPS35 in the risk of iRBD.

Increased incidence rates of narcolepsy type 1 (NT1) after the 2009-2010 H1N1 influenza pandemic (pH1N1) have been reported world-wide. While some European countries found an association between the NT1 increase and H1N1 vaccination Pandemrix, reports from Asian countries suggested the H1N1 virus rather than Pandemrix to be linked with the increase of new NT1 cases. We analyzed the number of de-novo NT1 cases in the last two decades until 2016 using the European Narcolepsy Network (EU-NN) database. Using robust data-driven modelling approaches we confirmed the peak of NT1 incidence in 2009-2010 pH1N1 and identified a new peak in 2013 that is age-specific for children/adolescents. Most of these de-novo cases showed a subacute disease onset consistent with an immune-mediated type of narcolepsy, which is most likely not related to Pandemrix vaccination that was used in 2009-2010, but may have been triggered by some new epidemiological event in Europe. Our finding of an unexpected peak in de-novo children narcolepsy in 2013 provides a unique opportunity to develop new hypotheses, such as considering other (influenza) viruses to further investigate the pathophysiology of immune-mediated narcolepsy.

ObjectiveTo study the role of GBA variants in the risk for isolated rapid-eye-movement (REM)-sleep behavior disorder (iRBD) and conversion to overt neurodegeneration.MethodsA total of 4,147 individuals were included: 1,061 iRBD patients and 3,086 controls. GBA was fully sequenced using molecular inversion probes and Sanger sequencing. We analyzed the effects of GBA variants on the risk for iRBD, age at onset (AAO) and conversion rates.ResultsGBA variants were found in 9.5% of iRBD patients compared to 4.1% in controls (odds ratio [OR]=2.45, 95% CI=1.87–3.22, p=1×10−10). The estimated OR for mild p.N370S variant carriers was 3.69, 95% CI=1.90–7.14, p=3.5×10−5, while for severe variant carriers it was 17.55, 95% CI=2.11–145.9, p=0.0015. Carriers of severe GBA variants had an average AAO of 52.8 years, 7-8 years earlier than those with mild variants or non-carriers (p=0.029). Of the GBA variant carriers with available data, 52.5% had converted, compared to 35.6% in non-carriers (p=0.011), with a trend for faster conversion among severe GBA variant carriers. However, the results on AAO and conversion were based on small numbers and should be taken with caution.ConclusionsGBA variants robustly and differentially increase the risk of iRBD. The rate of conversion to neurodegeneration is also increased and may be faster among severe GBA variant carriers, although confirmation will be required in larger samples. Screening for RBD in healthy carriers of GBA variants should be studied as a potential way to identify GBA variant carriers who will develop a synucleinopathy in the future.

ObjectiveREM-sleep behavior disorder (RBD) is a prodromal synucleinopathy, as >80% will eventually convert to overt synucleinopathy. We performed an in-depth analysis of the SNCA locus to identify RBD-specific risk variants.MethodsFull sequencing and genotyping of SNCA was performed in isolated/idiopathic RBD (iRBD, n=1,076), Parkinson’s disease (PD, n=1,013), and dementia with Lewy bodies (DLB, n=415), and in control subjects (n=6,155). A replication cohort from 23andMe of PD patients with probable RBD (pRBD) was also analyzed (cases n=1,782, controls n=131,250). Adjusted logistic regression models and meta-analyses were performed. Effects on conversion rate were analyzed in 432 RBD patients with available data using Kaplan-Meier survival analysis.ResultsA 5’-region SNCA variant (rs10005233) was associated with iRBD (OR=1.43, p=1.1E-08), which was replicated in pRBD. This variant is in linkage disequilibrium (LD) with other 5’ risk variants across the different synucleinopathies. An independent iRBD-specific suggestive association (rs11732740) was detected at the 3’ of SNCA (OR=1.32, p=4.7E-04, not statistically significant after Bonferroni correction). Homozygous carriers of both iRBD-specific SNPs were at highly increased risk for iRBD (OR=5.74, p=2E-06). The known top PD-associated variant (3’ variant rs356182) had an opposite direction of effect in iRBD compared to PD.InterpretationThere is a distinct pattern of association at the SNCA locus in RBD as compared to PD, with an opposite direction of effect at the 3’ of SNCA. Several 5’ SNCA variants are associated with iRBD and with pRBD in overt synucleinopathies, and may suggest a cognitive component to this region.

Type 1 narcolepsy (T1N) is a neurological condition, in which the death of hypocretin-producing neurons in the lateral hypothalamus leads to excessive daytime sleepiness and symptoms of abnormal Rapid Eye Movement (REM) sleep. Known triggers for narcolepsy are influenza-A infection and associated immunization during the 2009 H1N1 influenza pandemic. Here, we genotyped all remaining consented narcolepsy cases worldwide and assembled this with the existing genotyped individuals. We used this multi-ethnic sample in genome wide association study (GWAS) to dissect disease mechanisms and interactions with environmental triggers (5,339 cases and 20,518 controls). Overall, we found significant associations with HLA (2 GWA significant subloci) and 11 other loci. Six of these other loci have been previously reported (TRA, TRB, CTSH, IFNAR1, ZNF365 and P2RY11) and five are new (PRF1, CD207, SIRPG, IL27 and ZFAND2A). Strikingly, in vaccination-related cases GWA significant effects were found in HLA, TRA, and in a novel variant near SIRPB1. Furthermore, IFNAR1 associated polymorphisms regulated dendritic cell response to influenza-A infection in vitro (p-value =1.92*10−25). A partitioned heritability analysis indicated specific enrichment of functional elements active in cytotoxic and helper T cells. Furthermore, functional analysis showed the genetic variants in TRA and TRB loci act as remarkable strong chain usage QTLs for TRAJ*24 (p-value = 0.0017), TRAJ*28 (p-value = 1.36*10−10) and TRBV*4-2 (p-value = 3.71*10−117). This was further validated in TCR sequencing of 60 narcolepsy cases and 60 DQB1*06:02 positive controls, where chain usage effects were further accentuated. Together these findings show that the autoimmune component in narcolepsy is defined by antigen presentation, mediated through specific T cell receptor chains, and modulated by influenza-A as a critical trigger.