REM sleep behavior disorder and REM sleep without atonia as an early manifestation of degenerative neurological disease

Neuroscience in pictures: 2. Sleep, wakefulness, and mental state biology

Sleep is a vital restorative process that has occupied our curiosity for millennia. Despite our longstanding research efforts, the biology of sleep and its connection to mental states remains enigmatic. Unsurprisingly, sleep and wakefulness, the fundamental processes between which our mental states oscillate, are inseparable from our physical and mental health. Thus, clinical consideration of sleep impairments warrants a transdiagnostic approach whilst appropriately acknowledging that certain individual disorders (e.g. depression, schizophrenia) may have somewhat distinct sleep disturbances. Moreover, our knowledge of the anatomy and physiology of sleep regulation-albeit limited-forms the foundation for current treatments for sleep difficulties. This pictorial article overviews the core concepts and future of sleep neuroscience and mental state biology for trainees and practitioners in psychiatry and related professions.

MRI brain structural and functional networks changes in Parkinson disease with REM sleep behavior disorders

Background

Rapid eye movement sleep behavior disorder (RBD) is common in individuals with Parkinson's disease (PD). In spite of that, the precise mechanism underlying the pathophysiology of RBD among PD remains unclear.

Objective

The aim of the present study was to analyze gray matter volumes (GMVs) as well as the changes of functional connectivity (FC) among PD patients with RBD (PD-RBD) by employing a combination of voxel-based morphometry (VBM) and FC methods.

Methods

A total of 65 PD patients and 21 healthy control (HC) subjects were included in this study. VBM analyses were performed on all subjects. Subsequently, regions with significant different GMVs between PD patients with and without RBD (PD-nRBD) were selected for further analysis of FC. Correlations between altered GMVs and FC values with RBD scores were also investigated. Additionally, receiver operating characteristic (ROC) curves were employed for the evaluation of the predictive value of GMVs and FC in identifying RBD in PD.

Results

PD-RBD patients exhibited lower GMVs in the left middle temporal gyrus (MTG) and bilateral cuneus. Furthermore, we observed higher FC between the left MTG and the right postcentral gyrus (PoCG), as well as lower FC between the bilateral cuneus (CUN) and the right middle frontal gyrus (MFG) among PD-RBD patients in contrast with PD-nRBD patients. Moreover, the GMVs of MTG (extending to the right PoCG) was positively correlated with RBD severity [as measured by REM Sleep Behavior Disorder Screening Questionnaire (RBDSQ) score]. Conversely, the FC value between the bilateral CUN and the right MTG in PD-RBD patients was negatively correlated with RBDSQ score.

Conclusion

This study revealed the presence replace with GMV and FC changes among PD-RBD patients, which were closely linked to the severity of RBD symptoms. Furthermore, the combination of basic clinical characteristics, GMVs and FC values effectively predicted RBD for individuals with PD.

Educational Resources to Support Patients with Parasomnias

This article serves to help reduce patient burden in searching for credible information about parasomnias-abnormal behaviors during sleep-including sleepwalking, night terrors, and rapid eye movement sleep behavior disorder. It exhibits a compiled list of accessible online resources about parasomnias as well as detailed descriptions about each resource. By increasing patient accessibility to clinically validated resources, patients are more empowered to take an active role in managing their conditions, collaborating with their health-care practitioners in clinical management, enrolling in registries, and joining newsletters sponsored by these resources.

Sarcopenia in patients with isolated rapid eye movement sleep behavior disorder

OBJECTIVES

Evaluating of sarcopenia is important for promoting healthy aging, preventing functional decline, reducing the risk of falls and fractures, and improving overall quality of life. This study aimed to investigate sarcopenia in patients with isolated rapid eye movement sleep behavior disorder (RBD) using temporal muscle thickness (TMT) measurement.

METHODS

This investigation was retrospectively conducted at a single tertiary hospital. We recruited patients diagnosed with isolated RBD confirmed by polysomnography and clinical history and healthy participants as controls. Patients with isolated RBD and healthy controls underwent brain MRI scans, including three-dimensional T1-weighted imaging. We measured TMT, a radiographic marker of sarcopenia, based on the T1-weighted imaging. We compared the TMT between the groups and performed receiver operating characteristic (ROC) curve analysis to evaluate how well the TMT differentiated patients with isolated RBD from healthy controls. We also conducted a correlation analysis between the TMT and clinical factors.

RESULTS

Our study included 28 patients with isolated RBD and 30 healthy controls. There was a significant difference in the TMT of both groups. The TMT was reduced in patients with isolated RBD than in healthy controls (11.843 vs. 10.420 mm, p = 0.002). In the ROC curve analysis, the TMT exhibited good performance in differentiating patients with isolated RBD from healthy controls, with an area under the curve of 0.708. Furthermore, age was negatively correlated with TMT in patients with isolated RBD (r = -0.453, p = 0.015).

CONCLUSION

We demonstrate that TMT is reduced in patients with isolated RBD compared with healthy controls, confirming sarcopenia in patients with isolated RBD. The result suggests an association between neurodegeneration and sarcopenia. TMT can be used to evaluate sarcopenia in sleep disorders.

Comparison of quantitative REM without atonia parameters in isolated REM sleep behavior disorder and early untreated Parkinson's disease

OBJECTIVES

To analyze REM sleep without atonia (RWA) metrics in patients with isolated REM sleep behavior disorder (iRBD), Parkinson's disease (PD) and healthy subjects and compare them in terms of degree of presumed brainstem damage.

METHODS

Forty-nine iRBD patients, 62 PD patients and 38 healthy controls were included into the analysis. Detailed polysomnographic and clinical data including motor, olfactory, autonomic, and cognitive assessment were obtained in all participants and subsequently compared within groups without RBD (i.e., healthy controls, PD-RBD-) and with RBD (i.e., iRBD, PD-RBD+). SINBAR criteria were used to score RWA.

RESULTS

Twenty-one PD patients (33.8 %) had RBD. When comparing PD-RBD-patients and controls, RWA tonic (p = 0.001) and RWA mixed (p = 0.03) were higher in PD-RBD-group. PD-RBD-patients had worse olfactory function than controls (p < 0.001); no significant difference in autonomic or cognitive function was registered. There were no significant differences in RWA parameters when comparing iRBD and PD-RBD + groups. iRBD patients had better olfactory function than PD-RBD+ (p = 0.006); no significant difference in autonomic or cognitive function was registered. PD-RBD + had worse autonomic (p = 0.006) and olfactory (p = 0.001) but not motor and cognitive function compared to PD-RBD-.

CONCLUSIONS

Untreated de-novo PD patients without RBD have increased RWA metrics compared to healthy subjects indicating subclinical degeneration of brainstem nuclei responsible for RWA. iRBD patients do not differ in RWA metrics from untreated de-novo PD patients with premotor RBD suggesting a similar level of brainstem degeneration caudal to substantia nigra in both groups. Groups with RBD are associated with autonomic dysfunction.

Comparison of sleep characteristics between Parkinson's disease with and without freezing of gait: A systematic review

Parkinson's disease (PD) is a neurodegenerative disorder characterized by a range of motor and non-motor symptoms. Among the motor complaints, freezing of gait (FOG) is a common and disabling phenomenon that episodically hinders patients' ability to produce efficient steps. Concurrently, sleep disorders are prevalent in PD and significantly impact the quality of life of affected individuals. Numerous studies have suggested a bidirectional relationship between FOG and sleep disorders. Therefore, our objective was to systematically review the literature and compare sleep outcomes in PD patients with FOG (PD + FOG) and those without FOG (PD-FOG). By conducting a comprehensive search of the PubMed and Web of Science databases, we identified 20 eligible studies for inclusion in our analysis. Our review revealed that compared to PD-FOG, PD + FOG patients exhibited more severe symptoms of rapid eye movement sleep behavior disorder in nine studies, increased daytime sleepiness in eight studies, decreased sleep quality in four studies, and more frequent and severe sleep disturbances in four studies. These findings indicate that PD + FOG patients generally experience worse sleep quality, higher levels of daytime sleepiness, and more disruptive sleep disturbances compared to those without FOG (PD-FOG). The association between sleep disturbances and FOG highlights the importance of evaluating and monitoring these symptoms in PD patients and open the possibility for future studies to assess the impact of managing sleep disturbances on the severity and occurrence of FOG, and vice versa.

Severity of REM sleep without atonia correlates with measures of cognitive impairment and depressive symptoms in REM sleep behaviour disorder

This study aimed to correlate REM sleep without atonia (RSWA) and neuropsychological data in patients with idiopathic/isolated REM sleep behaviour disorder (iRBD) and those with RBD associated with Parkinson's disease (PDRBD), in order to assess whether higher degrees of RSWA are related to poorer cognitive performance. A total of 142 subjects were enrolled: 48 with iRBD, 55 with PDRBD, and 39 PD without RBD (PDnoRBD). All participants underwent video-polysomnographic recording, clinical and neuropsychological assessment. RSWA was quantified according to two manual scoring methods (Montréal, SINBAR) and one automated (REM atonia index, RAI). Mild cognitive impairment (MCI) was diagnosed according to diagnostic criteria for MCI in Parkinson's disease. The relationship between neuropsychological scores and RSWA metrics was explored by multiple linear regression analysis and logistic regression models. Patients with iRBD showed significantly lower visuospatial functions and working memory, compared with the others. More severe RSWA was associated with a higher risk of reduced visuospatial abilities (OR 0.15), working memory (OR 2.48), attention (OR 2.53), and semantic fluency (OR 0.15) in the iRBD. In the whole group, a greater RSWA was associated with an increased risk for depressive symptoms (OR 3.6). A total of 57(40%) MCI subjects were found (17 iRBD, 26 PDRBD, and 14 PDnoRBD). Preserved REM-atonia was associated with a reduced odds of multi-domain MCI in the whole study population (OR 0.54). In conclusion, a greater severity of RSWA was associated with an increased risk for poor cognitive performance and depressive mood in patients with RBD. Moreover, higher RAI was associated with a lower risk of multi-domain MCI.

The Genetic Basis of Probable REM Sleep Behavior Disorder in Parkinson's Disease

Patients with Parkinson's Disease (PD) experience REM sleep behavior disorder (RBD) more frequently than healthy controls. RBD is associated with torpid disease evolution. To test the hypothesis that differential genetic signatures might contribute to the torpid disease evolution in PD patients with RBD we compared the rate of genetic mutations in PD patients with or without probable RBD. Patients with a clinical diagnosis of PD in the Parkinson's Progression Markers Initiative (PPMI) database entered the study. We excluded those with missing data, dementia, psychiatric conditions, or a diagnosis change over the first five years from the initial PD diagnosis. Probable RBD (pRBD) was confirmed by a REM Sleep Behavior Disorder Screening Questionnaire score > 5 points. Logistic regression and Machine Learning (ML) algorithms were used to relate Single Nucleotide Polymorphism (SNPs) in PD-related genes with pRBD. We included 330 PD patients fulfilling all inclusion and exclusion criteria. The final logistic multivariate model revealed that the following SNPs increased the risk of pRBD: GBA_N370S_rs76763715 (OR, 95% CI: 3.38, 1.45-7.93), SNCA_A53T_rs104893877 (8.21, 2.26-36.34), ANK2. CAMK2D_rs78738012 (2.12, 1.08-4.10), and ZNF184_rs9468199 (1.89, 1.08-3.33). Conversely, SNP COQ7. SYT17_rs11343 reduced pRBD risk (0.36, 0.15-0.78). The ML algorithms led to similar results. The predictive models were highly specific (95-99%) but lacked sensitivity (9-39%). We found a distinctive genetic signature for pRBD in PD. The high specificity and low sensitivity of the predictive models suggest that genetic mutations are necessary but not sufficient to develop pRBD in PD. Additional investigations are needed.

Magnetic susceptibility changes in the brainstem reflect REM sleep without atonia severity in isolated REM sleep behavior disorder

REM sleep without atonia (RWA) is the hallmark of isolated REM sleep behavior disorder (iRBD) and is caused by neurodegeneration of brainstem structures. Previously, quantitative susceptibility mapping (QSM) was shown to detect microstructural tissue changes in neurodegenerative diseases. The goal of the study was to compare brainstem magnetic susceptibility (MS) in iRBD and controls using the voxel-based QSM approach and to examine the association between brainstem MS and severity of RWA in iRBD. Sixty iRBD patients and 41 healthy controls were included in the study. Phasic, tonic, mixed RWA and SINBAR score was quantified. QSM maps were reconstructed with QSMbox software from a multi-gradient-echo sequence acquired at 3T MRI system and normalized using a custom T1 template. Voxel-based analysis with age and gender as covariates was performed using a two-sample t-test model for between-group comparison and using a linear regression model for association with the RWA parameters. Statistical maps were generated using threshold free cluster enhancement with p-value p < 0.05, corrected for family wise error. Compared to controls, the iRBD group had higher MS in bilateral substantia nigra (SN), red nucleus and the ventral tegmental area. MS positively correlated with iRBD duration in the right pedunculotegmental nucleus and white matter of caudal mesencephalic and pontine tegmentum and with phasic RWA in bilateral SN. QSM was able to detect MS abnormalities in several brainstem structures in iRBD. Association of MS levels in the brainstem with the intensity of RWA suggests that increased iron content in SN is related to RWA severity.

Common Sleep Disorders Affecting Older Adults

Sleep disorders in older adults increase with aging, likely due to increased sleep latency, decreased sleep efficiency, and total sleep time. Common sleep issues include chronic insomnia, circadian rhythm sleep-wake disorders, sleep-related movement disorders, and sleep-disordered breathing. Diagnostic tools, such as a comprehensive sleep history and questionnaires, or a sleep log for more specific complaints, are commonly used. Polysomnography is not recommended as a routine test; however, it can be used for abnormal behaviors during sleep or if treatment fails. Sleep disorder management is based on the etiology and may include nonpharmacological and pharmacological alternative treatments. For example, nonpharmacological management for chronic insomnia and some sleep disorders may consist of cognitive behavioral therapy, sleep hygiene education, relaxation therapy, sleep restriction, light therapy, and stimulus control therapy. Because the quality of evidence for pharmacological treatment is poor, the medication choice should be based on shared decision-making between the practitioner and the patient, with limited prescription.

Sleep impairments in refugees diagnosed with post-traumatic stress disorder: a polysomnographic and self-report study

Background: Post-traumatic stress disorder (PTSD) is the clinical manifestation of traumatic events and is associated with sleep disturbances. Sleep disturbances, if left untreated, may perpetuate or even worsen symptoms of PTSD. Previous studies of other PTSD populations show a higher incidence of sleep impairments and sleep disorders compared to healthy controls (HCs); however, this has never been investigated in trauma-affected refugees diagnosed with PTSD.Objectives: To examine subjective sleep quality, measure sleep architecture, and identify latent sleep disorders in refugees diagnosed with PTSD compared to HCs.Method: This comparative study included 20 trauma-affected refugees diagnosed with PTSD and 20 HC matched on age, sex, and body mass index. All participants completed self-report questionnaires assessing sleep quality, insomnia severity, and disturbing nocturnal behaviour, and all took part in a one-night polysomnography (PSG) assessment.Results: Patients reported significantly poorer subjective sleep quality, sleep latency, sleep duration, and sleep efficiency compared to HCs. Subjective reports on hours spent in bed were not significantly different between patients and HCs. Patients reported significantly higher nightmare frequency and severity compared to HCs. PSG measures showed that patients had significantly reduced sleep efficiency, more awakenings, and longer REM sleep latency, and spent more time awake, whereas there was no significant differences regarding total time in bed, total sleep time, or sleep latency. The prevalence of sleep disorders was equal between groups.Conclusions: The study identified significant impairments in several sleep domains, with a preponderance of disturbed regulation of sleep resulting in awakenings. These results indicate a need for more focus on hyperarousal and nightmares as key elements of disturbed sleep in PTSD. Furthermore, the study identified a discrepancy between subjective and objective measures concerning total sleep time, raising questions regarding the causes of 'sleep state misperception'.Trial registration: ClinicalTrials.gov identifier: NCT03535636..Trial registration: Sleep Impairments in Refugees Diagnosed with PTSD (PSG-PTSD). URL: https://clinicaltrials.gov/ct2/show/NCT03535636. ClinicalTrials.gov NCT03535636. Date of registration: 24/05/2018.

Tonic REM sleep muscle activity is the strongest predictor of phenoconversion risk to neurodegenerative disease in isolated REM sleep behaviour disorder

Previous studies have shown that rapid eye movement sleep without atonia during polysomnography can predict the risk of phenoconversion to neurodegenerative disease in patients with isolated rapid eye movement sleep behaviour disorder. Discrepancy remains with regards to the morphology of rapid eye movement sleep without atonia that best predicts phenoconversion risk. This study aimed to ascertain the predictive value of tonic, phasic and mixed rapid eye movement sleep without atonia in patients with isolated rapid eye movement sleep behaviour disorder, at time of diagnosis. Sixty-four patients with polysomnography-confirmed isolated rapid eye movement sleep behaviour disorder, including 19 who phenoconverted during follow-up, were identified from an existing database. Tonic, phasic, mixed and "any" rapid eye movement sleep without atonia activity from the mentalis, tibialis anterior and flexor digitorum superficialis muscles was analysed blind to status using the diagnostic polysomnography. Rapid eye movement sleep without atonia variables were compared between converters and non-converters. Rapid eye movement sleep without atonia cut-offs predicting phenoconversion were established using receiver-operating characteristic analysis. The mean follow-up duration was 5.50 ± 4.73 years. Phenoconverters (n = 19) had significantly higher amounts of tonic (22.2 ± 19.1%, p = 0.0014), mixed (18.1 ± 14.1%, p = 0.0074) and "any" (mentalis muscle; 58.7 ± 28.0%, p = 0.0009) and all muscles (68.0 ± 20.8%, p = 0.0049) rapid eye movement sleep without atonia at diagnosis than non-converters. Optimal rapid eye movement sleep without atonia cut-off values predicting phenoconversion were 5.8% for tonic (73.7% sensitivity; 75.6% specificity), 7.3% for mixed (68.4% sensitivity; 73.3% specificity) and 43.6% for "any" (mentalis muscle; 68.4% sensitivity; 80.0% specificity) activity. "Any" (mentalis muscle) rapid eye movement sleep without atonia had the highest area under the curve (0.809) followed by tonic (0.799). The percentage of tonic rapid eye movement sleep without atonia was the strongest biomarker of phenoconversion in this cohort of patients with isolated rapid eye movement sleep behaviour disorder.

Recent advances in Lewy body dementia: A comprehensive review

Lewy Body Dementia is the second most frequent neurodegenerative illness proven to cause dementia, after Alzheimer's disease (AD). It is believed to be vastly underdiagnosed, as there is a significant disparity between the number of cases diagnosed clinically and those diagnosed via neuropathology at the time of postmortem autopsy. Strikingly, many of the pharmacologic treatments used to treat behavioral and cognitive symptoms in other forms of dementia exacerbate the symptoms of DLB. Therefore, it is critical to accurately diagnose DLB as these patients require a specific treatment approach. This article focuses on its pathophysiology, risk factors, differentials, and its diverse treatment modalities. In this study, an English language literature search was conducted on Medline, Cochrane, Embase, and Google Scholar till April 2022. The following search strings and Medical Subject Headings (MeSH) terms were used: "Lewy Body Dementia," "Dementia with Lewy bodies," and "Parkinson's Disease Dementia." We explored the literature on Lewy Body Dementia for its epidemiology, pathophysiology, the role of various genes and how they bring about the disease, biomarkers, its differential diagnoses and treatment options.

Predictors of dream enactment behavior among medical students: The case of the University of Gondar, Ethiopia

INTRODUCTION

Dream enactment behavior is one of the features of rapid eye movement sleep behavior disorder. It might be a manifestation of neurodegenerative diseases and can lead to fall associated injuries. There is no evidence of dream enactment behavior and its associated factors in Ethiopia. Hence, this study targeted to pinpoint the predictors of dream enactment behavior among Medical students at the University of Gondar.

METHODS

The cross-sectional survey was carried out at the University of Gondar among Medical students selected by simple random sampling technique from Dec 2020 to Feb 2021. We used a structured pretested questionnaire to collect the data and dream enactment behavior was evaluated using rapid eye movement sleep behavior disorder single question. Descriptive statistics were computed, and determinant factors were identified using binary logistic regression model. In the final model, explanatory variables with a p<0.05 were considered as predictors (statistically significant) of the dream enactment behavior. The strength of association was determined using adjusted odds ratio (AOR) with its 95% CI.

RESULTS

Four-hundred and twelve students took part in the study with 97.4% response rate. The mean age of participants was 20.82(±1.88) years and 291(70.63%) were males. The prevalence of dream enactment was 34.47% (95% CI: 30.02-39.20). Daytime sleepiness score (AOR = 1.104; 95% CI: 1.053-1.160), age (AOR = 1.15; 95% CI: 1.019-1.290), monthly pocket money (AOR = 0.9991; 95% CI: 0.9985-0.9997), alcohol drink (AOR = 2.71; 95% CI: 1.076-6.846), and perceived stress (AOR = 3.854; 95% CI: 1.802-8.242) were statistically significant factors of dream enactment behavior.

CONCLUSIONS

In this study, the magnitude of dream enactment behavior was high which was significantly associated with daytime sleepiness score, age, monthly pocket money, alcohol drink, and perceived stress all of which are modifiable except age. The University of Gondar has to plan a strategy to avert the condition via the prevention of the determinant factors. Students need to reduce stress and avoid alcohol drink. We strongly urge forthcoming scholars to ascertain association of dream enactment and academic performance of university students.

Cardiac Autonomic Dysfunction Is Associated with Severity of REM Sleep without Atonia in Isolated REM Sleep Behavior Disorder

123I-metaiodobenzylguanidine (MIBG) cardiac scintigraphy was performed to assess cardiac autonomic dysfunction and demonstrate its correlation with clinical and polysomnographic characteristics in patients with isolated rapid eye movement (REM) sleep behavior disorder. All subjects including 39 patients with isolated REM sleep behavior disorder and 17 healthy controls underwent MIBG cardiac scintigraphy for cardiac autonomic dysfunction assessment. The isolated REM sleep behavior disorder was confirmed by in-lab overnight polysomnography. A receiver operating curve was constructed to determine the cut-off value of the early and delayed heart-to-mediastinum ratio in patients with isolated REM sleep behavior disorder. Based on each cut-off value, a comparison analysis of REM sleep without atonia was performed by dividing isolated REM sleep behavior disorder patients into two groups. MIBG uptake below the cut-off value was associated with higher REM sleep without atonia. The lower heart-to-mediastinum ratio had significantly higher REM sleep without atonia (%), both with cut-off values of early (11.0 ± 5.6 vs. 29.3 ± 23.2%, p = 0.018) and delayed heart-to-mediastinum ratio (9.1 ± 4.3 vs. 30.0 ± 22.9%, p = 0.011). These findings indicate that reduced MIBG uptake is associated with higher REM sleep without atonia in isolated REM sleep behavior disorder.

Development of a Smart Sleep Mask with Multiple Sensors

In this work, we demonstrated a Smart Sleep Mask with several integrated physiological sensors such as 3-axis accelerometers, respiratory acoustic sensor, and an eye movement sensor. In particular, using infrared optical sensors, eye movement frequency, direction, and amplitude can be directly monitored and recorded during sleep sessions. We also developed a mobile app for data storage, signal processing and data analytics. Aggregation of these signals from a single wearable device may offer ease of use and more insights for sleep monitoring and REM sleep assessment. The user-friendly mask design can enable at-home use applications in the studies of digital biomarkers for sleep disorder related neurodegenerative diseases. Examples include REM Sleep Behavior Disorder, epilepsy event detection and stroke induced facial and eye movement disorder.Clinical Relevance-Many diseases such as stroke, epilepsy, and Parkinson's disease can cause significant abnormal events during sleep or are associated with sleep disorder. A smart sleep mask may serve as a simple platform to provide various physiological signals and generate clinical meaningful insights by revealing the neurological activities during various sleep stages.

Sleep Disturbances and Phenoconversion in Patients with REM Sleep Behavior Disorder

Objective: We aimed to investigate relationships between sleep disturbances and phenoconversion to neurodegenerative diseases in patients with REM sleep behavior disorder (RBD). Method: Using a comprehensive sleep database in a university-affiliated hospital between December 2014 and March 2021, we reviewed the data of 226 patients with RBD (182 patients with idiopathic RBD (iRBD) and 44 patients with symptomatic RBD (sRBD) with a neurodegenerative disease). Results: Among 226 patients with RBD (male, 61.5%), the mean age at RBD onset and mean disease duration were 59.4 ± 10.5 and 5.9 ± 5.6 years, respectively. Further, 111 (49.1%) patients had periodic limb movements during sleep (PLMS, PLM index ≥ 15/h), while 110 patients (48.7%) had comorbid obstructive sleep apnea (OSA, respiratory disturbance index ≥ 15/h). There was a positive correlation between age at RBD onset and the apnea-hypopnea index and Pittsburgh Sleep Quality Index. Compared to patients with iRBD, patients with sRBD showed a lower N3 sleep (3.3 ± 5.0 vs. 1.6 ± 3.1%, p = 0.004) and higher periodic limb movement index (36.3 ± 31.8 vs. 56.9 ± 47.5/h, p = 0.021) at the baseline. Among the 186 patients with iRBD, 18 (8.0%) developed neurodegenerative diseases (converters, mean follow-up duration: 2.5 ± 1.6 years) and 164 did not (non-converters, mean follow-up 2.4 ± 2.2 years). There was no significant between-group difference in the demographics and baseline clinical features. Continuous positive airway pressure (CPAP) therapy was prescribed in 101 patients with OSA; among them, 71 (70%) patients agreed to use it. CPAP improved dream enactment behaviors. Conclusion: In our study, 8.0% of patients with iRBD showed phenoconversion within a mean follow-up duration of 2.5 years. Polysomnographic parameters could not predict phenoconversion to neurodegenerative disease. However, approximately half of the patients with RBD presented with significant sleep disorders, including OSA or PLMS. CPAP therapy may alleviate RBD symptoms in patients with RBD-OSA.

Gastric Electrical Dysarrhythmia in Probable Rapid Eye Movement Sleep Behavior Disorder

Background: Subjective gastrointestinal complaints have been repeatedly reported in patients with REM sleep behavior disorder (RBD), but objective evidence is scarce. We aimed to objectively investigate the gastrointestinal dysfunction in individuals with probable RBD (pRBD) using an electrogastrogram. Methods: Thirty-two participants with pRBD and 60 age- and gender-matched healthy controls were enrolled. pRBD was diagnosed based on questionnaires and further assessed by experienced neurologists. After thorough assessment of participants' subjective gastrointestinal symptoms, preprandial and postprandial gastric activities were measured using an electrogastrogram. Dominant frequency, dominant power ratio, and the ratio of preprandial to postprandial power were analyzed. Results: Among the gastric symptoms, hiccup (34.8 vs. 9.6%, p = 0.017) and postprandial gastric discomfort (43.5 vs. 15.4%, p = 0.017) were more frequent in participants with pRBD than in controls. The dominant frequency on the electrode overlying the gastric pyloric antrum was lower in pRBD than in healthy controls (2.9 [2.6-2.9] vs. 2.9 [2.9-3.2] cpm, p = 0.006). A reduced dominant power ratio from the same electrode was also found in individuals with pRBD (60.7 [58.0-64.5] vs. 64.2 [58.7-69.6] %, p = 0.046). Conclusion: Patients with pRBD have a higher rate of gastric dysfunction, which presented as irregular slow wave rhythmicity on an electrogastrogram.

Rapid Eye Movement Behavior Disorder and Other Parasomnias

Rapid eye movement (REM) behavior disorder (RBD) is characterized by loss of skeletal muscle atonia that can lead to dream enactment. This condition can cause harm to patients and their bed partners if appropriate safety measures are not ensured. This condition is often the initial presenting symptom in a group of complex neurodegenerative processes. Definitive diagnosis requires a thorough history and an in-laboratory polysomnogram to look for evidence of REM sleep without atonia. Treatment options are limited but consist of sleep safety measures and pharmacotherapy. Patients diagnosed with idiopathic RBD associated with alpha-synucleinopathy are likely to have progression of disease.

Effect of TAAR1/5-HT1A agonist SEP-363856 on REM sleep in humans

SEP-363856 is a trace amine-associated receptor 1 (TAAR1) and 5-hydroxytryptamine type 1A (5-HT_1A) agonist, currently in Phase 3 clinical trials for the treatment of schizophrenia. Although SEP-363856 activates TAAR1 and 5-HT_1A receptors in vitro, an accessible marker of time- and concentration-dependent effects of SEP-363856 in humans is lacking. In rodents, SEP-363856 has been shown to suppress rapid eye movement (REM) sleep. The aim of the current study was to translate the REM sleep effects to humans and determine pharmacokinetic/pharmacodynamic (PK/PD) relationships of SEP-363856 on a measure of brain activity. The effects of SEP-363856 were evaluated in a randomized, double-blind, placebo-controlled, 2-way crossover study of single oral doses (50 and 10 mg) on REM sleep in healthy male subjects (N = 12 at each dose level). Drug concentrations were sampled during sleep to interpolate individual subject's pharmacokinetic trajectories. SEP-363856 suppressed REM sleep parameters with very large effect sizes (>3) following single doses of 50 mg and plasma concentrations ≥100 ng/mL. Below that effective concentration, the 10 mg dose elicited much smaller effects, increasing only the latency to REM sleep (effect size = 1). The PK/PD relationships demonstrated that REM sleep probability increased as drug concentrations declined below 100 ng/mL over the course of the night. SEP-363856 was generally safe and well tolerated at both doses. The REM sleep-suppressing effects of SEP-363856 provide an accessible marker of brain activity, which can aid in dose selection and help elucidate its therapeutic potential in further clinical trials.

Quantitative REM Sleep without Atonia in Parkinson's Disease and Essential Tremor

Background

Rapid eye movement (REM) sleep behavior disorder (RBD) occurs occasionally in essential tremor (ET), but polysomnographic REM sleep without atonia (RSWA) analyses have been sparse.

Objective

To characterize the amount and distribution of polysomnographic RSWA, the electrophysiologic substrate of RBD, in patients with Parkinson's disease (PD) and ET.

Methods

We analyzed quantitative RSWA in 73 patients: PD (23), ET (23), and age-sex-matched controls (27). None had dream-enactment behavior history or received antidepressants. Phasic, tonic, "any," and phasic-burst duration RSWA measures were calculated in the submentalis (SM) and anterior tibialis (AT) muscles. The automated REM atonia index (RAI) was also determined. Statistical analysis was performed by Kruskal-Wallis rank-sum and Mann-Whitney tests.

Results

SM phasic RSWA was significantly greater for PD than ET patients and controls (12.5% ± 12.8% vs. 4.9% ± 6.7%, 3.9% ± 2.6%), as was SM "any" (13.54% ± 14.30% vs. 5.2% ± 7.6%, 4.2% ± 2.6%). RAI was significantly lower in PD than in ET and controls (0.78 ± 0.23 vs. 0.92 ± 0.09 vs. 0.90 ± 0.17, P ≤ 0.005), but no different between ET and controls. AT phasic and "any" RSWA was similar between the 3 groups. ET and control RSWA was similar in all measures. Two ET patients (8.7%) had SM RSWA similar to PD patients.

Conclusions

Elevated SM RSWA distinguished PD from ET in patients without dream-enactment symptoms and occurs frequently in PD patients, and in isolated tremor suggests underlying synucleinopathy. Prospective studies will further validate these findings.

Timeline of Rapid Eye Movement Sleep Behavior Disorder in Overt Alpha-Synucleinopathies

OBJECTIVE

The aim was to analyze the timeline, prevalence, and survival of rapid eye movement (REM) sleep behavior disorder (RBD) in patients who developed alpha-synucleinopathies (Parkinson disease, dementia with Lewy bodies, and Parkinson disease dementia) compared with age- and sex-matched controls in a population-based incident-cohort study.

METHODS

We used a population-based, 1991 to 2010 incident-cohort study of alpha-synucleinopathies. A movement-disorder specialist reviewed medical records to confirm diagnoses. RBD was diagnosed by reported dream-enactment symptoms or polysomnography. Probable RBD and polysomnographically confirmed RBD were analyzed separately and combined.

RESULTS

Among the 444 incident cases of alpha-synucleinopathy, 86 were clinically diagnosed with RBD (19.8%), including 30 (35%) by polysomnography and 56 (65%) as probable. The prevalence of idiopathic RBD at alpha-synucleinopathy diagnosis was 3.4%, increasing to 23.8% after 15 years. Cumulative lifetime incidence was 53 times greater in alpha-synucleinopathy patients than in controls (odds ratio [OR] = 53.1, 95% confidence interval [CI]: 13.0-217.2, p < 0.0001), higher in dementia with Lewy bodies than in Parkinson disease (OR = 2.57, 95% CI: 1.50-4.40, p = 0.0004), and higher in men than in women with Parkinson disease, dementia with Lewy bodies, or Parkinson disease dementia (OR = 3.70, 95% CI: 2.07-6.62, p < 0.0001), but did not increase mortality risk.

INTERPRETATION

Our cohort had RBD incidence of 3.4%. Overall RBD increased to 23.8% after 15 years, with an overall incidence of 2.5 cases per 100 person-years. With 53 times greater lifetime incidence in alpha-synucleinopathy patients than in controls, RBD was more likely to develop in dementia with Lewy bodies than in Parkinson disease or Parkinson disease dementia, and in men than in women, but did not increase mortality risk within our cohort. ANN NEUROL 2021;89:293-303.

Effect of Yokukansan for the Treatment of Idiopathic Rapid Eye Movement Sleep Behavior Disorder: A Retrospective Analysis of Consecutive Patients

STUDY OBJECTIVES

The herbal medicine Yokukansan (YKS; Yi-Gan San in Chinese) is reported to be effective for treating rapid eye movement sleep behavior disorder (RBD). However, the effectiveness and safety of YKS treatment have not been confirmed in a large sample. Thus, we retrospectively analyzed the outcomes of YKS treatment on patients with RBD using clinical records.

METHODS

Treatment outcomes were evaluated using the Clinical Global Impression of Illness Severity (CGI-S) and Improvement (CGI-I) scales. Patients with scores of 1 (very much improved) and 2 (much improved) on the CGI-I were classified as responders. After excluding patients with very mild RBD symptoms and those without detailed clinical information, 36 patients with idiopathic RBD including 17 receiving YKS monotherapy and 19 receiving YKS add-on therapy in addition to other medication were analyzed.

RESULTS

The patients' mean age [standard deviation, SD] was 69.3 [6.8] years, and the mean duration of RBD morbidity [SD] was 5.7 [3.5] years at the start of YKS treatment. Importantly, 12 of 17 patients (70.6%) receiving YKS monotherapy were responders. However, among patients receiving YKS add-on therapy, the proportion of responders was substantially lower (4 of 19 patients; 21.1%). No adverse events were reported, other than mild gastric distress in one case.

CONCLUSIONS

Considering the effectiveness of YKS and the low likelihood of adverse events, YKS should be considered as a potential treatment for patients with RBD.

CITATION

Matsui K, Sasai-Sakuma T, Ishigooka J, Nishimura K, Inoue Y. Effect of yokukansan for the treatment of idiopathic rapid eye movement sleep behavior disorder: a retrospective analysis of consecutive patients. J Clin Sleep Med. 2019;15(8):1173-1178.

REM Sleep without atonia correlates with abnormal vestibular-evoked myogenic potentials in isolated REM sleep behavior disorder

STUDY OBJECTIVES

The neurophysiological hallmark of REM sleep behavior disorder (RBD) is loss of atonia during REM sleep. Indeed, signs and symptoms of neurodegeneration can occur after years, even decades, from its beginning. This study aimed to measure neurophysiological alterations of the brainstem that potentially correlate with the severity of atonia loss, and determining whether a prodromal neurodegenerative disorder underlines this condition when it occurs as an isolated condition (iRBD).

METHODS

Subjects with iRBD and matched healthy controls were recruited. The study included the recording of one-night polysomnography, vestibular-evoked myogenic potentials (VEMPs), and a [123I]-FP-CIT dopamine transporter (DAT) scan. The quantification of REM sleep without atonia (RSWA) was made according to two previously published manual methods and one automated method.

RESULTS

The rate of alteration of VEMPs and VEMP score were significantly higher in iRBD patients than controls. Moreover, VEMP score was negatively correlated with the automated REM atonia index; a marginal statistical significance was also reached for the positive correlation with the visual tonic electromyographic parameter, while the other correlations, including that with DAT-scan score were not statistically significant.

CONCLUSIONS

Brainstem neurophysiology in iRBD can be assessed by VEMPs and their alterations may possibly indicate an early expression of the neurodegenerative process underlying this disorder at the brainstem level, which awaits future longitudinal confirmation. The correlation between RSWA and VEMP alteration might also represent a prodromal aspect anticipating the possible evolution from iRBD to neurodegeneration, whereas DAT-scan abnormalities might represent a later step in this evolution.

Muscle Activity Detection during Sleep by Ear-EEG

Muscle activation during sleep is an important biomarker in the diagnosis of several sleep disorders and neurodegenerative diseases. Muscle activity is typically assessed manually based on the EMG channels from polysomnography recordings. Ear-EEG provides a mobile and comfortable alternative for sleep assessment. In this study, ear-EEG was used to automatically detect muscle activities during sleep. The study was based on a dataset comprising four full night recordings from 20 healthy subjects with concurrent polysomnography and ear-EEG. A binary label, active or relax, extracted from the chin EMG was assigned to selected 30 s epoch of the sleep recordings in order to train a classifier to predict muscle activation. We found that the ear-EEG based classifier detected muscle activity with an accuracy of 88% and a Cohen's kappa value of 0.71 relative to the labels derived from the chin EMG channels. The analysis also showed a significant difference in the distribution of muscle activity between REM and non-REM sleep.

Automatic Sleep Disorders Classification Using Ensemble of Bagged Tree Based on Sleep Quality Features

Sleep disorder is a medical disease of the sleep patterns, which commonly suffered by the elderly. Sleep disorders diagnosis and treatment are considered to be challenging due to a time-consuming and inconvenient process for the patient. Moreover, the use of Polysomnography (PSG) in sleep disorder diagnosis is a high-cost process. Therefore, we propose an efficient classification method of sleep disorder by merely using electrocardiography (ECG) signals to simplify the sleep disorders diagnosis process. Different from many current related studies that applied a five-minute epoch to observe the main frequency band of the ECG signal, we perform a pre-processing technique that suitable for the 30-seconds epoch of the ECG signal. By this simplification, the proposed method has a low computational cost so that suitable to be implemented in an embedded hardware device. Structurally, the proposed method consists of five stages: (1) pre-processing, (2) spectral features extraction, (3) sleep stage detection using the Decision-Tree-Based Support Vector Machine (DTB-SVM), (4) assess the sleep quality features, and (5) sleep disorders classification using ensemble of bagged tree classifiers. We evaluate the effectiveness of the proposed method in the task of classifying the sleep disorders into four classes (insomnia, Sleep-Disordered Breathing (SDB), REM Behavior Disorder (RBD), and healthy subjects) from the 51 patients of the Cyclic Alternating Pattern (CAP) sleep data. Based on experimental results, the proposed method presents 84.01% of sensitivity, 94.17% of specificity, 86.27% of overall accuracy, and 0.70 of Cohen’s kappa. This result indicates that the proposed method able to reliably classify the sleep disorders merely using the 30-seconds epoch ECG in order to address the issue of a multichannel signal such as the PSG.

Posttraumatic stress disorder increases the odds of REM sleep behavior disorder and other parasomnias in Veterans with and without comorbid traumatic brain injury

STUDY OBJECTIVES

To describe the crude prevalence of rapid eye movement (REM) sleep behavior disorder (RBD) following traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD) in Veterans, given potential relationships between TBI, PTSD, RBD, and neurodegeneration.

METHODS

Veterans (n = 394; 94% male; 54.4 ± 15.5 years of age) were prospectively/cross-sectionally recruited from the VA Portland Health Care System and completed in-lab video-polysomnography and questionnaires. TBI and PTSD were assessed via diagnostic screening and medical record review. Subjects were categorized into four groups after assessment of REM sleep without atonia (RSWA) and self-reported dream enactment: (1) "Normal," neither RSWA nor dream enactment, (2) "Other Parasomnia," dream enactment without RSWA, (3) "RSWA," isolated-RSWA without dream enactment, and (4) "RBD," RSWA with dream enactment. Crude prevalence, prevalence odds ratio, and prevalence rate for parasomnias across subjects with TBI and/or PTSD were assessed.

RESULTS

Overall prevalence rates were 31%, 7%, and 9% for Other Parasomnia, RSWA, and RBD, respectively. The prevalence rate of RBD increased to 15% in PTSD subjects [age adjusted POR: 2.81 (1.17-4.66)] and to 21% in TBI + PTSD subjects [age adjusted POR: 3.43 (1.20-9.35)]. No subjects met all diagnostic criteria for trauma-associated sleep disorder (TASD), and no overt dream enactment was captured on video.

CONCLUSIONS

The prevalence of RBD and related parasomnias is significantly higher in Veterans compared with the general population and is associated with PTSD and TBI + PTSD. Considering the association between idiopathic-RBD and synucleinopathy, it remains unclear whether RBD (and potentially TASD) associated with PTSD or TBI + PTSD similarly increases risk for long-term neurologic sequelae.

Rapid Eye Movement Sleep Behavior Disorder and Neurodegenerative Diseases: An Update

Rapid eye movement sleep behavior disorder (RBD) is a sleep behavior disorder characterized by abnormal behaviors and loss of muscle atonia during rapid eye movement (REM) sleep. RBD is generally considered to be associated with synucleinopathies, such as Parkinson’s disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA), and usually precedes years before the first symptom of these diseases. It is believed that RBD predicts the neurodegeneration in synucleinopathy. However, increasing evidences have shown that RBD is also found in non-synucleinopathy neurodegenerative diseases, including Alzheimer’s disease (AD), Huntington’s disease (HD), amyotrophic lateral sclerosis (ALS), etc. Sleep disturbance such as RBD may be an early sign of neurodegeneration in these diseases, and also serve as an assessment of cognitive impairments. In this review, we updated the clinical characteristics, diagnosis, and possible mechanisms of RBD in neurogenerative diseases. A better understanding of RBD in these neurogenerative diseases will provide biomarkers and novel therapeutics for the early diagnosis and treatment of the diseases.

Rapid Eye Movement (REM) Sleep Behavior Disorder and REM Sleep with Atonia in the Young

BACKGROUND

Rapid eye movement (REM) sleep behavior disorder (RBD) and REM sleep without atonia (RWA) have assumed much clinical importance with long-term data showing progression into neurodegenerative conditions among older adults. However, much less is known about RBD and RWA in younger populations. This study aims at comparing clinical and polysomnographic (PSG) characteristics of young patients presenting with RBD, young patients with other neurological conditions, and normal age-matched subjects.

METHODS

A retrospective chart review was carried out for consecutive young patients (<25 years) presenting with clinical features of RBD; and data were compared to data from patients with epilepsy, attention deficit hyperactivity disorder (ADHD), and autism, as well as normal subjects who underwent PSG during a 2-year-period.

RESULTS

Twelve patients fulfilling RBD diagnostic criteria, 22 autism patients, 10 with ADHD, 30 with epilepsy, and 14 normal subjects were included. Eight patients with autism (30%), three with ADHD (30%), one with epilepsy (3.3%), and six patients who had presented with RBD like symptoms (50%) had abnormal movements and behaviors during REM sleep. Excessive transient muscle activity and/or sustained muscle activity during REM epochs was found in all patients who had presented with RBD, in 16/22 (72%) autistic patients, 6/10 (60%) ADHD patients compared to only 6/30 (20%) patients with epilepsy and in none of the normal subjects.

CONCLUSION

We observed that a large percentage of young patients with autism and ADHD and some with epilepsy demonstrate loss of REM-associated atonia and some RBD-like behaviors on polysomnography similar to young patients presenting with RBD.

Technologies for Monitoring Lifestyle Habits Related to Brain Health: A Systematic Review

Brain health refers to the preservation of brain integrity and function optimized for an individual’s biological age. Several studies have demonstrated that our lifestyles habits impact our brain health and our cognitive and mental wellbeing. Monitoring such lifestyles is thus critical and mobile technologies are essential to enable such a goal. Three databases were selected to carry out the search. Then, a PRISMA and PICOTS based criteria for a more detailed review on the basis of monitoring lifestyle aspects were used to filter the publications. We identified 133 publications after removing duplicates. Fifteen were finally selected from our criteria. Many studies still use questionnaires as the only tool for monitoring and do not apply advanced analytic or AI approaches to fine-tune results. We anticipate a transformative boom in the near future developing and implementing solutions that are able to integrate, in a flexible and adaptable way, data from technologies and devices that users might already use. This will enable continuous monitoring of objective data to guide the personalized definition of lifestyle goals and data-driven coaching to offer the necessary support to ensure adherence and satisfaction.

REM sleep muscle activity in idiopathic REM sleep behavior disorder predicts phenoconversion

OBJECTIVE

To determine whether REM sleep without atonia (RSWA) during polysomnography (PSG) predicts phenoconversion in patients with idiopathic REM sleep behavior disorder (iRBD), a prodromal feature of a neurodegenerative disease.

METHODS

We analyzed RSWA in 60 patients with iRBD, including manual phasic, tonic, and any muscle activity in the submentalis and anterior tibialis muscles and the automated REM atonia index in the submentals. We identified patients who developed parkinsonism or mild cognitive impairment (MCI) during at least 3 years of follow-up after PSG. Kaplan-Meier analysis was performed and receiver operator curves were calculated to determine RSWA cutoffs predicting faster phenoconversion.

RESULTS

Twenty-six (43%) patients developed parkinsonism (n = 17) or MCI (n = 9). Phenoconverters were older at iRBD diagnosis (p = 0.02). Median time to phenoconversion was 3.9 ± 2.5 years. iRBD phenoconverters had significantly more RSWA at diagnosis. Phenoconversion risk from iRBD diagnosis was 20% and 35% at 3 and 5 years, respectively, with greater risk in patients with iRBD with >46.4% any combined RSWA, which increased further to 30% and 55% at 3 and 5 years for patients >65 years of age at diagnosis.

CONCLUSIONS

Patients with iRBD with higher amounts of polysomnographic RSWA had a greater risk of developing Parkinson disease or MCI. Patients with older age and higher RSWA amounts had more rapid phenoconversion than younger patients with RBD. Our study suggests that RSWA is a potential biomarker for risk stratification of iRBD phenoconversion that could facilitate prognostication for patients with iRBD.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that for patients with iRBD, increased RSWA correlates with increased risk for developing parkinsonism or MCI.

Simultaneous tonic and phasic REM sleep without atonia best predicts early phenoconversion to neurodegenerative disease in idiopathic REM sleep behavior disorder

Study Objectives

Rapid eye movement (REM) sleep without atonia (RWA) is the main polysomnographic feature of idiopathic REM sleep behavior disorder (iRBD) and is considered to be a promising biomarker predicting conversion to manifested synucleinopathy. Besides conventionally evaluated tonic, phasic and any RWA, we took into consideration also periods, when phasic and tonic RWA appeared simultaneously and we called this activity “mixed RWA.” The study aimed to evaluate different types of RWA, to reveal the most relevant biomarker to the conversion.

Methods

A total of 55 patients with confirmed iRBD were recruited with mean follow-up duration 2.3 ± 0.7 years. Scoring of RWA was based on Sleep Innsbruck Barcelona rules. Positive phenocoversion was ascertained according to standard diagnostic criteria during follow-up. Receiver operator characteristic analysis was applied to evaluate predictive performance of different RWA types.

Results

A total of nine patients (16%) developed neurodegenerative diseases. Yearly phenoconversion rate was 5.5%. Significantly higher amounts of mixed (p = 0.009), tonic (p = 0.020), and any RWA (p = 0.049) were found in converters. Optimal cutoffs differentiating the prediction were 16.4% (sensitivity 88.9; specificity 69.6) for tonic, 4.4% (sensitivity 88.9; specificity 60.9) for mixed, and 36.8% (sensitivity 77.8; specificity 65.2) for any RWA. With area under the curve (AUC) 0.778, mixed RWA has proven to be the best predictive test followed by tonic (AUC 0.749) and any (AUC 0.710).

Conclusions

Mixed, tonic and any RWA may serve as biomarkers predicting the conversion into neurodegenerative disease in iRBD. The best predictive value lies within mixed RWA, thus it should be considered as standard biomarker.

Remembering to Forget: A Dual Role for Sleep Oscillations in Memory Consolidation and Forgetting

It has been known since the time of patient H. M. and Karl Lashley's equipotentiality studies that the hippocampus and cortex serve mnestic functions. Current memory models maintain that these two brain structures accomplish unique, but interactive, memory functions. Specifically, most modeling suggests that memories are rapidly acquired during waking experience by the hippocampus, before being later consolidated into the cortex for long-term storage. Sleep has been shown to be critical for the transfer and consolidation of memories in the cortex. Like memory consolidation, a role for sleep in adaptive forgetting has both historical precedent, as Francis Crick suggested in 1983 that sleep was for "reverse-learning," and recent empirical support. In this article I review the evidence indicating that the same brain activity involved in sleep replay associated memory consolidation is responsible for sleep-dependent forgetting. In reviewing the literature, it became clear that both a cellular mechanism for systems consolidation and an agreed upon general, as well as cellular, mechanism for sleep-dependent forgetting is seldom discussed or is lacking. I advocate here for a candidate cellular systems consolidation mechanism wherein changes in calcium kinetics and the activation of consolidative signaling cascades arise from the triple phase locking of non-rapid eye movement sleep (NREMS) slow oscillation, sleep spindle and sharp-wave ripple rhythms. I go on to speculatively consider several sleep stage specific forgetting mechanisms and conclude by discussing a notional function of NREM-rapid eye movement sleep (REMS) cycling. The discussed model argues that the cyclical organization of sleep functions to first lay down and edit and then stabilize and integrate engrams. All things considered, it is increasingly clear that hallmark sleep stage rhythms, including several NREMS oscillations and the REMS hippocampal theta rhythm, serve the dual function of enabling simultaneous memory consolidation and adaptive forgetting. Specifically, the same sleep rhythms that consolidate new memories, in the cortex and hippocampus, simultaneously organize the adaptive forgetting of older memories in these brain regions.

A case-control-family study of idiopathic rapid eye movement sleep behavior disorder

OBJECTIVE

To determine the familial aggregation of idiopathic rapid eye movement sleep behavior disorder (iRBD), neurodegenerative diseases, and related biomarkers.

METHODS

A total of 404 and 387 first-degree relatives of 102 patients with iRBD and of 89 controls were recruited, respectively. Among them, 204 and 208 relatives of patients and controls underwent face-to-face clinical assessment, whereas 97 and 75 relatives underwent further video-polysomnographic assessment, respectively.

RESULTS

Compared with relatives of controls, relatives of patients demonstrated higher levels of RBD features, including chin tonic electromyography activity (mean = 1.5 ± 7.5 vs 0.3 ± 1.0, p = 0.04) and behavioral events (n [weighted %] = 12 [11.3] vs 2 [1.9], adjusted hazard ratio [aHR] = 7.69, 95% confidence interval [CI] = 1.54-33.33, p = 0.009) during rapid eye movement sleep, probable diagnosis (n [%] = 57 [14.9] vs 20 [4.9], aHR = 3.45, 95% CI = 1.96-6.25, p < 0.001), and definite diagnosis (n [weighted %] = 10 [8.4] vs 2 [1.4], aHR = 5.56, 95% CI = 1.16-25.00, p = 0.03). They also had higher risks of Parkinson disease (3.1% vs 0.5%, aHR = 5.88, 95% CI = 1.37-25.00, p = 0.02), dementia (6.9% vs 2.6%, aHR = 2.44, 95% CI = 1.15-5.26, p = 0.02), constipation (8.3% vs 2.4%, adjusted odds ratio = 4.21, 95% CI = 1.34-13.17, p = 0.01), and motor dysfunction (Movement Disorders Society Unified Parkinson's Disease Rating Scale part III motor score, mean = 1.9 ± 3.2 vs 0.9 ± 2.3, p = 0.002). The unaffected relatives of patients demonstrated a higher likelihood ratio of prodromal Parkinson disease (median [interquartile range] = 0.27 [1.19] vs 0.22 [0.51], p = 0.03).

INTERPRETATION

iRBD is familially aggregated from isolated features to full-blown sleep disorder. Relatives of patients carry a higher risk of alpha-synucleinopathy in terms of neurodegenerative diseases and prodromal markers, suggesting a familial aggregation and staging pathology of alpha-synucleinopathy. Ann Neurol 2019;85:582-592.

High-Order Visual Processing, Visual Symptoms, and Visual Hallucinations: A Possible Symptomatic Progression of Parkinson's Disease

Objective: To determine whether Parkinson disease (PD) patients with (VH) have different clinical characteristics and gray-matter volume than those with visual misperceptions (VM) or other visual symptoms (OvS). Background: The spectrum of visual complaints in PD is broad and complex. Methods: We conducted a retrospective chart review of 525 PD patients to identify the frequency of visual symptoms and the association with clinical and radiological features. Brain volumetric MRI data was analyzed using multivariate logistic regression to differentiate cases with and without visual symptoms. Results: Among 525 PD cases, visual complaints were documented in 177 (33.7%). Among these, 83 (46.9%) had VH, 31 (17.5%) had VM, and 63 (35.6%) had OvS (diplopia, blurry vision, photophobia, dry eyes, and eye pain or soreness). When compared to OvS, patients with VH had significantly higher age, duration of disease, rate of REM sleep behavior disorder, and cognitive impairment. Visual hallucinations patients had decreased age-adjusted volumetric averages in 28/30 gray-matter regions when compared to PD without visual symptoms and 30/30 gray-matter regions when compared to VM patients. Conclusions: Visual symptoms in PD may represent a spectrum from OvS to VM to VH, with progression of the latter associated with older age, duration of disease, presence of REM sleep behavior disorder, cognitive impairment, and decreased gray-matter volume.

Video polysomnographic findings in non-rapid eye movement parasomnia

Although video polysomnography (vPSG) is not routinely recommended for the evaluation of typical cases of non-rapid eye movement (NREM) parasomnias, it can aid diagnosis of unusual cases, other sleep disorders and complicated cases with REM behaviour disorder (RBD), and in differentiating parasomnias from epilepsy. In this study, we aimed to assess vPSG findings in consecutive patients with a clinical diagnosis of NREM-parasomnia covering the whole phenotypic spectrum. Five hundred and twelve patients with a final diagnosis of NREM parasomnia who had undergone vPSG were retrospectively identified. vPSGs were analysed for features of NREM parasomnia and for the presence of other sleep disorders. Two hundred and six (40.0%) patients were clinically diagnosed with sleepwalking, 72 (14.1%) with sleep terrors, 39 (7.6%) with confusional arousals, 15 (2.9%) with sexsomnia, seven (1.4%) with sleep-related eating disorder, 122 (23.8%) with mixed phenotype, and 51 (10.0%) with parasomnia overlap disorder (POD). The vPSG supported the diagnosis of NREM parasomnia in 64.4% of the patients and of POD in 98%. In 28.9% of the patients, obstructive sleep apnea (OSA) or/and periodic limb movements during sleep (PLMS) were identified, most commonly in older, male, sleepy and obese patients. vPSG has a high diagnostic yield in patients with NREM parasomnia and should be routinely performed when there is diagnostic doubt, or in patients where there is a suspicion of OSA and PLMS.

Diagnostic Approach and Investigation in Sleep Medicine

PURPOSE OF REVIEW

This article provides a clinical approach to the appropriate investigation and diagnosis of sleep disorders commonly seen by neurologists.

RECENT FINDINGS

Home sleep apnea testing in appropriate situations can replace laboratory polysomnography in many cases of uncomplicated sleep apnea. Multiple sleep latency tests must be performed meticulously and interpreted in the clinical setting to avoid overdiagnoses of narcolepsy. Human leukocyte antigen testing has limited utility in establishing a diagnosis of narcolepsy because a positive test has low specificity. Rapid eye movement (REM) sleep behavior disorder is frequently the first manifestation of an evolving synucleinopathy, and a careful history and neurologic examination are needed to determine other early features of these disorders.

SUMMARY

A meticulous history from the patient, supplemented by collateral history from an observer, is essential to establishing the diagnosis of sleep disorders. Judicious supplementary use of investigations, such as laboratory polysomnography, home sleep apnea testing, wrist actigraphy, and multiple sleep latency tests, can confirm the correct diagnosis. This article describes an approach to the sleepy patient, the patient with neuromuscular disease and possible sleep-disordered breathing, the patient with restless legs syndrome, and young and older patients with abnormal movements during sleep.

An overview of sleep and circadian dysfunction in Parkinson's disease

Sleep and circadian alterations are amongst the very first symptoms experienced in Parkinson's disease, and sleep alterations are present in the majority of patients with overt clinical manifestation of Parkinson's disease. However, the magnitude of sleep and circadian dysfunction in Parkinson's disease, and its influence on the pathophysiology of Parkinson's disease remains often unclear and a matter of debate. In particular, the confounding influences of dopaminergic therapy on sleep and circadian dysfunction are a major challenge, and need to be more carefully addressed in clinical studies. The scope of this narrative review is to summarise the current knowledge around both sleep and circadian alterations in Parkinson's disease. We provide an overview on the frequency of excessive daytime sleepiness, insomnia, restless legs, obstructive apnea and nocturia in Parkinson's disease, as well as addressing sleep structure, rapid eye movement sleep behaviour disorder and circadian features in Parkinson's disease. Sleep and circadian disorders have been linked to pathological conditions that are often co-morbid in Parkinson's disease, including cognitive decline, memory impairment and neurodegeneration. Therefore, targeting sleep and circadian alterations could be one of the earliest and most promising opportunities to slow disease progression. We hope that this review will contribute to advance the discussion and inform new research efforts to progress our knowledge in this field.

REM Sleep Behavior Disorder in Parkinson's Disease and Other Synucleinopathies

Rapid eye movement sleep behavior disorder is characterized by dream enactment and complex motor behaviors during rapid eye movement sleep and rapid eye movement sleep atonia loss (rapid eye movement sleep without atonia) during polysomnography. Rapid eye movement sleep behavior disorder may be idiopathic or symptomatic and in both settings is highly associated with synucleinopathy neurodegeneration, especially Parkinson's disease, dementia with Lewy bodies, multiple system atrophy, and pure autonomic failure. Rapid eye movement sleep behavior disorder frequently manifests years to decades prior to overt motor, cognitive, or autonomic impairments as the presenting manifestation of synucleinopathy, along with other subtler prodromal "soft" signs of hyposmia, constipation, and orthostatic hypotension. Between 35% and 91.9% of patients initially diagnosed with idiopathic rapid eye movement sleep behavior disorder at a sleep center later develop a defined neurodegenerative disease. Less is known about the long-term prognosis of community-dwelling younger patients, especially women, and rapid eye movement sleep behavior disorder associated with antidepressant medications. Patients with rapid eye movement sleep behavior disorder are frequently prone to sleep-related injuries and should be treated to prevent injury with either melatonin 3-12 mg or clonazepam 0.5-2.0 mg to limit injury potential. Further evidence-based studies about rapid eye movement sleep behavior disorder are greatly needed, both to enable accurate prognostic prediction of end synucleinopathy phenotypes for individual patients and to support the application of symptomatic and neuroprotective therapies. Rapid eye movement sleep behavior disorder as a prodromal synucleinopathy represents a defined time point at which neuroprotective therapies could potentially be applied for the prevention of Parkinson's disease, dementia with Lewy bodies, multiple system atrophy, and pure autonomic failure. © 2017 International Parkinson and Movement Disorder Society.

REM Sleep Behavior Disorder: Diagnosis, Clinical Implications, and Future Directions

Rapid eye movement sleep behavior disorder (RBD) is diagnosed by a clinical history of dream enactment accompanied by polysomnographic rapid eye movement sleep atonia loss (rapid eye movement sleep without atonia). Rapid eye movement sleep behavior disorder is strongly associated with neurodegenerative disease, especially synucleinopathies such as Parkinson disease, dementia with Lewy bodies, and multiple system atrophy. A history of RBD may begin several years to decades before onset of any clear daytime symptoms of motor, cognitive, or autonomic impairments, suggesting that RBD is the presenting manifestation of a neurodegenerative process. Evidence that RBD is a synlucleinopathy includes the frequent presence of subtle prodromal neurodegenerative abnormalities including hyposmia, constipation, and orthostatic hypotension, as well as abnormalities on various neuroimaging, neurophysiological, and autonomic tests. Up to 90.9% of patients with idiopathic RBD ultimately develop a defined neurodegenerative disease over longitudinal follow-up, although the prognosis for younger patients and antidepressant-associated RBD is less clear. Patients with RBD should be treated with either melatonin 3 to 12 mg or clonazepam 0.5 to 2.0 mg to reduce injury potential. Prospective outcome and treatment studies of RBD are necessary to enable accurate prognosis and better evidence for symptomatic therapy and future neuroprotective strategies.

Sleep Disturbances in Frontotemporal Dementia

Sleep disorders appear to be frequent comorbidities in patients with frontotemporal dementia (FTD). Insomnia and excessive daytime sleepiness commonly occur in patients with FTD and significantly contribute to caregiver burden and burnout. Sleep is severely fragmented in FTD patients, likely secondary to behavioral disturbances, other primary sleep disorders such as sleep disordered breathing and restless leg syndrome, and neurodegeneration of nuclei involved in sleep and wakefulness. Treatment of primary sleep disorders may improve excessive daytime sleepiness and sleep quality and may improve daytime cognitive functioning. Rapid eye movement (REM) sleep behavior disorder is rare in FTD and may be confused with excessive nocturnal activity due to disturbed circadian rhythm. The relationship between FTD, sleep quality, and sleep disorders requires further study to better understand the contribution of disturbed sleep to daytime neurocognitive functioning and quality of life in FTD. Further, future studies should focus on comparing sleep disturbances between different FTD syndromes, especially behavioral variant FTD and primary progressive aphasia. Comorbid sleep disorders should be promptly sought and treated in patients with FTD to improve patient and caregiver quality of life.

Diagnostic REM sleep muscle activity thresholds in patients with idiopathic REM sleep behavior disorder with and without obstructive sleep apnea

OBJECTIVES

We aimed to determine whether visual and automated rapid eye movement (REM) sleep without atonia (RSWA) methods could accurately diagnose patients with idiopathic REM sleep behavior disorder (iRBD) and comorbid obstructive sleep apnea (OSA).

METHODS

In iRBD patients (n = 15) and matched controls (n = 30) with and without OSA, we visually analyzed RSWA phasic burst durations, phasic, tonic, and "any" muscle activity by 3-s mini-epochs, phasic activity by 30-s (AASM rules) epochs, and automated REM atonia index (RAI). Group RSWA metrics were analyzed with regression models. Receiver operating characteristic (ROC) curves were used to determine the best diagnostic cutoff thresholds for REM sleep behavior disorder (RBD). Both split-night and full-night polysomnographic studies were analyzed.

RESULTS

All mean RSWA phasic burst durations and muscle activities were higher in iRBD patients than in controls (p <0.01). Muscle activity (phasic, "any") cutoffs for 3-s mini-epoch scorings were as follows: submentalis (SM) (15.8%, 19.5%), anterior tibialis (AT) (29.7%, 29.7%), and combined SM/AT (39.5%, 39.5%). The tonic muscle activity cutoff was 0.70% and RAI (SM) cutoff 0.86. The phasic muscle burst duration cutoffs were 0.66 s for SM and 0.71 s for AT. Combining phasic burst durations with RSWA muscle activity improved the sensitivity and specificity of iRBD diagnosis.

CONCLUSIONS

This study provides evidence for quantitative RSWA diagnostic thresholds applicable in iRBD patients with OSA. Our findings in this study were very similar to those seen in patients with Parkinson's disease-REM sleep behavior disorder (PD-RBD), consistent with a common mechanism and presumed underlying etiology of synucleinopathy in both groups.

The Prevalence and Characteristics of REM Sleep without Atonia (RSWA) in Patients Taking Antidepressants

STUDY OBJECTIVES

The association of REM sleep without atonia (RSWA) as well as REM sleep behavior disorder (RBD) with the intake of selective serotonin reuptake inhibitors (SSRI) and selective norepinephrine reuptake inhibitors (SNRI) is well established. Our study objective was to determine the prevalence of RSWA and RBD among a group of sleep center patients taking SSRI and SNRI.

METHODS

A retrospective chart review was done at our tertiary sleep center, and 10,746 consecutive records from October 1, 2007, through October 31, 2013, were searched for SSRI and SNRI names using the Sleep Cataloguer Software.

RESULTS

The search resulted in 1,444 records, which were then reviewed for keywords of RSWA and RBD. The AASM scoring criteria were used to determine RSWA. Reports of 41 patients with known narcolepsy or α-synucleinopathies were excluded. The remaining records were mined for age, sex, presence of obstructive sleep apnea (OSA), type of antidepressant (SSRI or SNRI), and diagnosis for which antidepressant was prescribed. We used logistic regression analysis to adjust for age, OSA, and sex. Of the 1,444 participants on antidepressants, 176 (12.2%) had RSWA (all confirmed by the investigators) compared to 226 of the entire sleep lab population of 10,746 (2.1%), risk ratio (95% CI) 9.978 (8.149, 12.22). Seven of the 176 patients on antidepressants had RBD (0.48%) compared to 108 of 10,746 (1%), p = 0.005.

CONCLUSIONS

SSRI and SNRI are associated with a higher prevalence of RSWA but not of RBD. This is independent of medication type.

Distinct Parameters in the EEG of the PLP α-SYN Mouse Model for Multiple System Atrophy Reinforce Face Validity

Multiple system atrophy (MSA) is a neurodegenerative movement disorder characterized by parkinsonian symptoms and cerebellar symptoms. Sleep disturbances also play a crucial role in MSA. One of the most convincing animal models in MSA research is the PLP α-SYN model, but to date no studies on sleep disturbances in this mouse model, frequently found in MSA patients are available. We identified spectral shifts within the EEG of the model, strikingly resembling results of clinical studies. We also characterized muscle activity during REM sleep, which is one of the key symptoms in REM sleep behavioral disorder. Spectral shifts and REM sleep-linked muscle activity were age dependent, supporting Face Validity of the PLP α-SYN model. We also strongly suggest our findings to be critically evaluated for Predictive Validity in future studies. Currently, research on MSA lacks potential compounds attenuating or curing MSA. Future drugs must prove its potential in animal models, for this our study provides potential biomarkers.

Rapid eye movement sleep without atonia may help diagnose Lewy body disease in middle-aged and older patients with somatic symptom disorder

BACKGROUND

Lewy body disease (LBD), including Parkinson's disease (PD) and dementia with Lewy bodies (DLB), is defined pathologically as degeneration in the central and peripheral nervous system associated with Lewy bodies. Somatic symptom disorder often predates the clinical diagnosis of PD and DLB. It is crucial to make an initial diagnosis of LBD in patients with psychiatric symptoms because administering psychotropic drugs often causes or exacerbates extrapyramidal signs. Given the close association between rapid eye movement (REM) sleep behaviour disorder and LBD, REM sleep without atonia on polysomnography may help to diagnose LBD in middle-aged and older patients with somatic symptom disorder.

METHODS

We reviewed the clinical profiles of five patients with an initial diagnosis of somatic symptom disorder who exhibited REM sleep without atonia on polysomnography. There were three men and two women, with a mean age of 68.4 years (range: 55.0-78.0 years). The mean Mini-Mental State Examination score was 26 (range: 22-30).

RESULTS

Only two patients had a clinical history of dream-enacting behaviour and fulfilled the clinical criteria for REM sleep behaviour disorder, but clinical conditions in the other three patients corresponded to subclinical REM sleep behaviour disorder. Final clinical diagnoses were made as probable DLB in three patients; two patients did not meet the clinical criteria for PD or DLB. Neurological examinations revealed mild extrapyramidal signs in these two patients, and their scores on the motor component of the Unified Parkinson's Disease Rating Scale were 8 and 5 points, and their Mini-Mental State Examination scores were 30 points. Neither patient exhibited dream-enacting behaviour, but both had constipation. Cardiac ¹²³ I-metaiodobenzylguanidine scintigraphy revealed mild increased washout rates.

DISCUSSION

REM sleep without atonia may provide an opportunity to identify LBD in patients with somatic symptom disorder, even before they fulfil the clinical criteria for PD or DLB. Continued follow-up will be needed to determine whether these psychiatric patients are in the prodromal stage of PD or DLB.

Advanced Analysis of Pharmaco-Sleep Data in Humans

Pharmaco-sleep studies in humans aim at the description of the effects of drugs, most frequently substances that act on the central nervous system, by means of quantitative analysis of biosignals recorded in subjects during sleep. Up to 2007, the only standard for the classification of sleep macrostructure that found worldwide acceptance were the rules published in 1968 by Rechtschaffen and Kales. In May 2007, the AASM Manual for the Scoring of Sleep and Associated Events was published by the American Academy of Sleep Medicine, and concerning the classification of sleep stages, these new rules are supposed to replace those developed by Rechtschaffen and Kales. As compared to the rather low interrater reliability of manual sleep scoring, semiautomated approaches may achieve a reliability close to 1 (Cohen's kappa 0.99 for 2 semiautomated scorings as compared to 0.76 for 2 manual scorings) without any decline in validity. Depending on the aim of the pharmaco-sleep study, additional analyses concerning sleep fragmentation, sleep microstructure, sleep depth, sleep processes and local aspects of sleep should be considered. For some of these additional features, rules for visual scoring have been established, while for others automatic analysis is obligatory. Generally, for reasons of cost-effectiveness but also reliability, automatic analysis is preferable to visual analysis. However, the validity of the automatic method applied has to be proven.