REM sleep behavior disorder and degenerative dementia: an association likely reflecting Lewy body disease

Impaired cholinergic integrity of the colon and pancreas in dementia with Lewy bodies

Dementia with Lewy bodies is characterized by a high burden of autonomic dysfunction and Lewy pathology in peripheral organs and components of the sympathetic and parasympathetic nervous system. Parasympathetic terminals may be quantified with 18F-fluoroetoxybenzovesamicol, a PET tracer that binds to the vesicular acetylcholine transporter in cholinergic presynaptic terminals. Parasympathetic imaging may be useful for diagnostics, improving our understanding of autonomic dysfunction and for clarifying the spatiotemporal relationship of neuronal degeneration in prodromal disease. Therefore, we aimed to investigate the cholinergic parasympathetic integrity in peripheral organs and central autonomic regions of subjects with dementia with Lewy bodies and its association with subjective and objective measures of autonomic dysfunction. We hypothesized that organs with known parasympathetic innervation, especially the pancreas and colon, would have impaired cholinergic integrity. To achieve these aims, we conducted a cross-sectional comparison study including 23 newly diagnosed non-diabetic subjects with dementia with Lewy bodies (74 ± 6 years, 83% male) and 21 elderly control subjects (74 ± 6 years, 67% male). We obtained whole-body images to quantify PET uptake in peripheral organs and brain images to quantify PET uptake in regions of the brainstem and hypothalamus. Autonomic dysfunction was assessed with questionnaires and measurements of orthostatic blood pressure. Subjects with dementia with Lewy bodies displayed reduced cholinergic tracer uptake in the pancreas (32% reduction, P = 0.0003) and colon (19% reduction, P = 0.0048), but not in organs with little or no parasympathetic innervation. Tracer uptake in a region of the medulla oblongata overlapping the dorsal motor nucleus of the vagus correlated with autonomic symptoms (rs = -0.54, P = 0.0077) and changes in orthostatic blood pressure (rs = 0.76, P < 0.0001). Tracer uptake in the pedunculopontine region correlated with autonomic symptoms (rs = -0.52, P = 0.0104) and a measure of non-motor symptoms (rs = -0.47, P = 0.0230). In conclusion, our findings provide the first imaging-based evidence of impaired cholinergic integrity of the pancreas and colon in dementia with Lewy bodies. The observed changes may reflect parasympathetic denervation, implying that this process is initiated well before the point of diagnosis. The findings also support that cholinergic denervation in the brainstem contributes to dysautonomia.

Rapid eye movement sleep loss associated cytomorphometric changes and neurodegeneration

Rapid eye movement sleep (REMS) is essential for leading normal healthy living at least in higher-order mammals, including humans. In this review, we briefly survey the available literature for evidence linking cytomorphometric changes in the brain due to loss of REMS. As a mechanism of action, we add evidence that REMS loss elevates noradrenaline (NA) levels in the brain, which affects neuronal cytomorphology. These changes may be a compensatory mechanism as the changes return to normal after the subjects recover from the loss of REMS or if during REMS deprivation, the subjects are treated with NA-adrenoceptor antagonist prazosin (PRZ). We had proposed earlier that one of the fundamental functions of REMS is to maintain the level of NA in the brain. We elaborate on this idea to propose that if REMS loss continues without recovery, the sustained level of NA breaks down neurophysiologically active compensatory mechanism/s starting with changes in the neuronal cytomorphology, followed by their degeneration, leading to acute and chronic pathological conditions. Identification of neuronal cytomorphological changes could prove to be of significance for predicting future neuronal (brain) damage as well as an indicator for REMS health. Although current brain imaging techniques may not enable us to visualize changes in neuronal cytomorphology, given the rapid technological progress including use of artificial intelligence, we are optimistic that it may be a reality soon. Finally, we propose that maintenance of optimum REMS must be considered a criterion for leading a healthy life.

The brain-first vs. body-first model of Parkinson's disease with comparison to alternative models

The ultimate origin of Lewy body disorders, including Parkinson's disease (PD) and Dementia with Lewy bodies (DLB), is still incompletely understood. Although a large number of pathogenic mechanisms have been implicated, accumulating evidence support that aggregation and neuron-to-neuron propagation of alpha-synuclein may be the core feature of these disorders. The synuclein, origin, and connectome (SOC) disease model of Lewy body disorders was recently introduced. This model is based on the hypothesis that in the majority of patients, the first alpha-synuclein pathology arises in single location and spreads from there. The most common origin sites are the enteric nervous system and the olfactory system. The SOC model predicts that gut-first pathology leads to a clinical body-first subtype characterized by prodromal autonomic symptoms and REM sleep behavior disorder. In contrast, olfactory-first pathology leads to a brain-first subtype with fewer non-motor symptoms before diagnosis. The SOC model further predicts that body-first patients are older, more commonly develop symmetric dopaminergic degeneration, and are at increased risk of dementia-compared to brain-first patients. In this review, the SOC model is explained and compared to alternative models of the pathogenesis of Lewy body disorders, including the Braak staging system, and the Unified Staging System for Lewy Body Disorders. Postmortem evidence from brain banks and clinical imaging data of dopaminergic and cardiac sympathetic loss is reviewed. It is concluded that these datasets seem to be more compatible with the SOC model than with those alternative disease models of Lewy body disorders.

Narrative Review Concerning the Clinical Spectrum of Ophthalmological Impairments in Parkinson's Disease

Ophthalmic non-motor impairments are common in Parkinson's disease patients, from the onset of the neurodegenerative disease and even prior to the development of motor symptoms. This is a very crucial component of the potential for early detection of this disease, even in its earliest stages. Since the ophthalmological disease is extensive and impacts all extraocular and intraocular components of the optical analyzer, a competent assessment of it would be beneficial for the patients. Because the retina is an extension of the nervous system and has the same embryonic genesis as the central nervous system, it is helpful to investigate the retinal changes in Parkinson's disease in order to hypothesize insights that may also be applicable to the brain. As a consequence, the detection of these symptoms and signs may improve the medical evaluation of PD and predict the illness' prognosis. Another valuable aspect of this pathology is the fact that the ophthalmological damage contributes significantly to the decrease in the quality of life of patients with Parkinson's disease. We provide an overview of the most significant ophthalmologic impairments associated with Parkinson's disease. These results certainly constitute a large number of the prevalent visual impairments experienced by PD patients.

A postmortem study suggests a revision of the dual-hit hypothesis of Parkinson's disease

The dual-hit hypothesis of Parkinson's disease (PD) originally postulated that a neurotropic pathogen leads to formation of α-synuclein pathology in the olfactory bulb (OB) and dorsal motor nucleus of the vagus (DMV) and then invades the brain from these two entry points. Little work has been conducted to validate an important underlying premise for the dual-hit hypothesis, namely that the initial Lewy pathology does arise simultaneously in the OB and the enteric nervous system (ENS) plexuses and DMV at the earliest disease stage. We conducted a focused re-analysis of two postmortem datasets, which included large numbers of mild Lewy body disease (LBD) cases. We found that cases with α-synuclein pathology restricted to the peripheral autonomic nervous system and/or lower brainstem (early body-first LBD cases) very rarely had any OB pathology, suggesting that Lewy pathology commonly arises in the ENS without concomitant involvement of the OB. In contrast, cases with mild amygdala-predominant Lewy pathology (early brain-first LBD cases) nearly always showed OB pathology. This is compatible with the first pathology being triggered in the OB or amygdala followed by secondary spreading to connected structures, but without early involvement of the ENS or lower brainstem. These observations support that the pathologic process starts in either the olfactory bulb or the ENS, but rarely in the olfactory bulb and gut simultaneously. More studies on neuropathological datasets are warranted to reproduce these findings. The agreement between the revised single-hit hypothesis and the recently proposed brain-first vs. body-first model of LBD is discussed.

A critical review of the pharmacological treatment of REM sleep behavior disorder in adults: time for more and larger randomized placebo-controlled trials

Rapid Eye Movement sleep behavior disorder (RBD) is a parasomnia causing sufferers to physically act out their dreams. These behaviors can disrupt sleep and sometimes lead to injuries in patients and their bed-partners. Clonazepam and melatonin are the first-line pharmacological treatment options for RBD based on direct uncontrolled clinical observations and very limited double-blind placebo-controlled trials. Given the risk for adverse outcomes, especially in older adults, it is of great importance to assess the existing level of evidence for the use of these treatments. In this update, we therefore critically review the clinical and scientific evidence on the pharmacological management of RBD in people aged over 50. We focus on the first-line treatments, and provide an overview of all other alternative pharmacological agents trialed for RBD we could locate as supplementary materials. By amalgamating all clinical observations, our update shows that 66.7% of 1,026 RBD patients reported improvements from clonazepam and 32.9% of 137 RBD patients reported improvements from melatonin treatment on various outcome measures in published accounts. Recently, however, three relatively small randomized placebo-controlled trials did not find these agents to be superior to placebo. Given clonazepam and melatonin are clinically assumed to majorly modify or eliminate RBD in nearly all patients-there is an urgent need to test whether this magnitude of treatment effect remains intact in larger placebo-controlled trials.

Dementia with Lewy bodies research consortia: A global perspective from the ISTAART Lewy Body Dementias Professional Interest Area working group

Dementia with Lewy bodies (DLB) research has seen a significant growth in international collaboration over the last three decades. However, researchers face a challenge in identifying large and diverse samples capable of powering longitudinal studies and clinical trials. The DLB research community has begun to focus efforts on supporting the development and harmonization of consortia, while also continuing to forge networks within which data and findings can be shared. This article describes the current state of DLB research collaborations on each continent. We discuss several established DLB cohorts, many of whom have adopted a common framework, and identify emerging collaborative initiatives that hold the potential to expand DLB networks and diversify research cohorts. Our findings identify geographical areas into which the global DLB networks should seek to expand, and we propose strategies, such as the creation of data-sharing platforms and the harmonization of protocols, which may further potentiate international collaboration.

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.

Dream enactment behavior-a real nightmare: a review of post-traumatic stress disorder, REM sleep behavior disorder, and trauma-associated sleep disorder

NONE

Dream enactment behavior is a phenomenon demonstrated in patients with post-traumatic stress disorder, rapid eye movement sleep behavior disorder, as well as with a more recently described condition entitled trauma-associated sleep disorder, which shares diagnostic criteria for rapid eye movement sleep behavior disorder. While these conditions share some commonalities, namely dream enactment behavior, they are quite different in pathophysiology and underlying mechanisms. This review will focus on these 3 conditions, with the purpose of increasing awareness for trauma-associated sleep disorder in particular.

Residual Injurious Symptoms and Its Association With Neurodegenerative Outcomes in Idiopathic Rapid Eye Movement Sleep Behavior Disorder: A Retrospective, Longitudinal Follow-up Study

BACKGROUND

The risk of neurodegenerative disorders in idiopathic rapid eye movement sleep behavior disorder (iRBD) patients with residual injurious symptoms (RIS) after symptomatic treatment with clonazepam and/or melatonin is unclear.

OBJECTIVE

The objective of this study was to determine the rate and correlates of RIS and its association with the risk of neurodegenerative diseases in patients with iRBD.

METHODS

This was a retrospective cohort study. RIS was defined by the RBD Questionnaire-Hong Kong (RBDQ-HK) as the presence of residual sleep-related injuries or potential injurious behaviors for at least once a month after at least 1 year of treatment.

RESULTS

A total of 15 out of 133 (11.3%) patients with iRBD (age at diagnosis = 66.5 ± 7.3 years, 77.4% male) had RIS after 2.7 years of treatment. Patients with RIS were younger at both onset and polysomnography-confirmed diagnosis of iRBD (years, mean ± standard deviation, 56.3 ± 6.9 vs. 61.8 ± 7.6, P = 0.01; 61.2 ± 4.2 vs. 67.2 ± 7.4, P < 0.001, respectively), had more severe behavioral symptoms at diagnosis (both RBDQ-HK total score and behavioral subscore, P = 0.01), and used a higher maximum dose of clonazepam (mg; median [interquartile range], 1.5 [1.0] vs. 1.0 [1.0], P = 0.01). RIS was probably associated with a higher risk of developing dementia with Lewy bodies (adjusted hazard ratio [95% confidence interval], 5.47 [1.71-17.46], adjusted for onset age of RBD), but not Parkinsons's disease in the follow-up.

CONCLUSION

RIS is not uncommon in patients with iRBD despite long-term medication treatment. An earlier onset and more severe clinical profile are associated with RIS. The prediction of RIS toward dementia with Lewy bodies but not PD suggests that RIS may probably help to identify the specific risk of different subtypes of α-synucleinopathy. © 2020 International Parkinson and Movement Disorder Society.

Facilitatory/inhibitory intracortical imbalance in REM sleep behavior disorder: early electrophysiological marker of neurodegeneration?

STUDY OBJECTIVES

Previous studies found an early impairment of the short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) to transcranial magnetic stimulation (TMS) in Parkinson's disease. However, very little is known on the TMS correlates of rapid eye movement (REM) sleep behavior disorder (RBD), which can precede the onset of a α-synucleinopathy.

METHODS

The following TMS measures were obtained from 14 de novo patients with isolated RBD and 14 age-matched healthy controls: resting motor threshold, cortical silent period, latency and amplitude of the motor evoked potentials, SICI, and ICF. A cognitive screening and a quantification of subjective sleepiness (Epworth Sleepiness Scale [ESS]) and depressive symptoms were also performed.

RESULTS

Neurological examination, global cognitive functioning, and mood status were normal in all participants. ESS score was higher in patients, although not suggestive of diurnal sleepiness. Compared to controls, patients exhibited a significant decrease of ICF (median 0.8, range 0.5-1.4 vs. 1.9, range 1.4-2.3; p < 0.01) and a clear trend, though not significant, towards a reduction of SICI (median 0.55, range 0.1-1.4 vs. 0.25, range 0.1-0.3), with a large effect size (Cohen's d: -0.848). REM Sleep Atonia Index significantly correlated with SICI.

CONCLUSIONS

In still asymptomatic patients for a parkinsonian syndrome or neurodegenerative disorder, changes of ICF and, to a lesser extent, SICI (which are largely mediated by glutamatergic and GABAergic transmission, respectively) might precede the onset of a future neurodegeneration. SICI was correlated with the muscle tone alteration, possibly supporting the proposed RBD model of retrograde influence on the cortex from the brainstem.

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.

Pathological Influences on Clinical Heterogeneity in Lewy Body Diseases

PD, PD with dementia, and dementia with Lewy bodies are clinical syndromes characterized by the neuropathological accumulation of alpha-synuclein in the CNS that represent a clinicopathological spectrum known as Lewy body disorders. These clinical entities have marked heterogeneity of motor and nonmotor symptoms with highly variable disease progression. The biological basis for this clinical heterogeneity remains poorly understood. Previous attempts to subtype patients within the spectrum of Lewy body disorders have centered on clinical features, but converging evidence from studies of neuropathology and ante mortem biomarkers, including CSF, neuroimaging, and genetic studies, suggest that Alzheimer's disease beta-amyloid and tau copathology strongly influence clinical heterogeneity and prognosis in Lewy body disorders. Here, we review previous clinical biomarker and autopsy studies of Lewy body disorders and propose that Alzheimer's disease copathology is one of several likely pathological contributors to clinical heterogeneity of Lewy body disorders, and that such pathology can be assessed in vivo. Future work integrating harmonized assessments and genetics in PD, PD with dementia, and dementia with Lewy bodies patients followed to autopsy will be critical to further refine the classification of Lewy body disorders into biologically distinct endophenotypes. This approach will help facilitate clinical trial design for both symptomatic and disease-modifying therapies to target more homogenous subsets of Lewy body disorders patients with similar prognosis and underlying biology. © 2019 International Parkinson and Movement Disorder Society.

Unified Staging System for Lewy Body Disorders: Clinicopathologic Correlations and Comparison to Braak Staging

This study was designed to correlate clinical findings with the extent of pathologic a-synuclein (aSyn) in the brain using the Unified Staging System for Lewy Body disorders (USSLB). Data from 280 cases from the Arizona Study of Aging and Neurodegenerative Disorders are presented. Each case had a complete USSLB staging and at least 1 full research clinical assessment, including subspecialty neurologist-administered movement and cognitive evaluation. Of the 280, 25.7% were cognitively normal, 8.6% had mild cognitive impairment, and 65.7% had dementia. All cases could be categorized into 1 of 5 USSLB stages (8.6% stage I-olfactory bulb only; 15.4% IIa-brainstem predominant; 13.6% IIb-limbic predominant; 31.8% III-brainstem and limbic; and 30.7% IV-neocortical) yet using the Braak staging system 70 cases (25.3%) could not be classified. Those with USSLB stages III and IV died at a younger age. Multiple measures of motor parkinsonism, cognitive impairment, hyposmia, and probable RBD were significantly correlated with increasing USSLB stage. We conclude that the USSLB is the most comprehensive staging system for all Lewy body disorders and allows for categorization and ranking of all brains with significant correlations to many motor and nonmotor clinical signs and symptoms.

Clinical and video-polysomnographic analysis of rapid eye movement sleep behavior disorder and other sleep disturbances in dementia with Lewy bodies

Objective

The main objective of this study was to study rapid eye movement (REM) sleep behavior disorder (RBD) and other sleep disorders in dementia with Lewy bodies (DLB).

Methods

Consecutive patients with DLB and mild dementia severity were recruited irrespective of sleep complaints. Patients underwent clinical interview, assessment of sleep scales, and video-polysomnography (V-PSG). RBD was diagnosed with V-PSG based on electromyographic and audiovisual analysis.

Results

Thirty-five patients (65.7% men; mean age 77.7 ± 6.1 years) were evaluated. Poor sleep quality (54.3%), hypersomnia (37.1%), snoring (60%), and abnormal nocturnal behaviors (77.1%) were reported. Sleep–wake architecture abnormalities occurred in 75% patients and consisted of occipital slowing on awake electroencephalography (EEG; 34.4%), the absence of sleep spindles and K complexes (12.9%), slow frequency sleep spindles (12.9%), delta activity in REM sleep (19.2%), and REM sleep without atonia (44%). Three patients showed hallucinatory-like behaviors and 10 patients showed abnormal behaviors during arousals mimicking RBD. RBD was diagnosed in 50% of those patients in whom sufficient REM sleep was attained. Of these, 72.7% were not aware of displaying dream-enacting behaviors and in 63.7% RBD preceded the onset of cognitive impairment. For RBD diagnosis, the sensitivity of Mayo Sleep Questionnaire was 50%, specificity was 66.7%, positive predictive value was 83.3%, and negative predictive value was 28%. False-positive RBD cases according to clinical history had hallucinatory-like behaviors, severe obstructive sleep apnea, and prominent periodic limb movements in sleep. Occipital EEG frequency while awake and rate of electromyographic activity in REM sleep were negatively correlated, suggesting a common subcortical origin.

Conclusion

In DLB, RBD and sleep–wake disorders are common, heterogeneous, and complex, challenging their identification without performing V-PSG.

The Contribution of Tau, Amyloid-Beta and Alpha-Synuclein Pathology to Dementia in Lewy Body Disorders

Parkinson's Disease (PD) and the closely related Dementia with Lewy Bodies (DLB) are due to the accumulation of pathogenic alpha-synuclein protein in brain cells manifest by heterogeneous motor and non-motor symptoms, including cognitive impairment and dementia. The majority of patients with Parkinson's Disease develop Dementia (PDD) in late stages of the disease and have widespread neocortical distribution of alpha-synuclein pathology at autopsy, compared with PD without dementia, in which neocortical synuclein pathology is less prevalent. These three entities PD, DLB and PDD comprise a clinical spectrum, collectively known as Lewy Body Disorders (LBD). Recent investigations into the neuropathological basis of LBD have demonstrated that while synuclein pathology is the defining feature of these disorders, it is often accompanied by other age-related neurodegenerative pathologies. In particular, amyloid plaque and tau tangle pathology characteristic of Alzheimer's Disease (AD) (~50% of all LBD patients have sufficient pathology at autopsy for a secondary neuropathologic diagnosis of AD), appear to contribute to cognitive impairment in LBD, and the combination is associated with a shorter interval between onset of motor symptoms and development of dementia and a shorter life span. Further, the co-occurrence of neocortical alpha-synuclein, tau and amyloid pathologies found at end-stage disease suggests a potential synergistic interaction of these individual pathologies in humans during life, mirroring experimental observations in animal and cell model systems that show how pathogenic species of synuclein fibrils can promote trans-synaptic spread of both tauopathy and synucleinopathy with strain-like properties. Newer post-mortem studies using digital methods to measure pathologic burden have highlighted distinct neocortical patterns of areas with relative higher density of tau pathology in LBD compared to AD that support these model data. The emerging field of cerebrospinal fluid and molecular imaging biomarkers of synuclein, amyloid and tau pathologies in LBD is contributing to a greater understanding of how the different pathologies evolve and interact to produce clinical heterogeneity in LBD. Future work to elucidate biologically meaningful clinical subgroups of synucleinopathy and its co-pathology must focus on the full clinicopathological spectrum of LBD and use validated biomarkers, when available, to design clinical trials based on the precise selection of homogeneous patient subgroups to maximize statistical power for detecting the impact of treatment.

REM behavior disorder predicts motor progression and cognitive decline in Parkinson disease

Objective

To investigate whether REM sleep behavior disorder (RBD) is associated with worse motor and cognitive decline in Parkinson disease (PD)

Methods

Four-hundred twenty-one drug-naive patients with early-stage PD and 196 controls without PD were included in this study. All participants underwent a [123I]FP-CIT SPECT scan, CSF assessment, 3-tesla MRI, and thorough clinical assessments.

Results

At cross-sectional analyses, patients with PD and probable RBD (PD-RBD) had lower CSF β-amyloid 1–42 (Aβ42) levels and higher total tau to Aβ42 CSF ratio, higher nonmotor symptoms burden, and worse scores on neuropsychological tests of processing speed, visuospatial functioning, and delayed recognition memory compared to patients with PD without RBD. At longitudinal analyses, the presence of RBD was associated with faster motor progression (hazard ratio [HR] = 1.368, 95% confidence Interval [CI] = 1.036–1.806; p = 0.027) and cognitive decline (HR = 1.794, 95% CI = 1.163–2.768; p = 0.008) over 60-month follow-up. The presence of RBD was a predictor for motor progression only in patients with PD who had both low α-synuclein levels and low [123I]FP-CIT uptake in the striatum (HR = 2.091, 95% CI = 1.116–3.918; p = 0.021) and a predictor for cognitive decline only in patients with PD who had both low Aβ42 and low α-synuclein levels (HR = 2.810, 95% CI = 1.462–5.400; p = 0.002). In the population of controls without PD, the presence of RBD was not associated with cognitive decline or any baseline pathologic changes.

Conclusion

The presence of RBD in PD is associated with faster motor progression in patients with greater synuclein and dopaminergic pathology, and with higher risk of cognitive decline in patients with greater synuclein and amyloid pathology. Our findings provide an important direction toward understanding phenotypes and their prognosis in PD.

Rapid eye movement sleep behavior disorder and the link to alpha-synucleinopathies

Rapid eye movement (REM) sleep behavior disorder (RBD) involves REM sleep without atonia in conjunction with a recurrent nocturnal dream enactment behavior, with vocalizations such as shouting and screaming, and motor behaviors such as punching and kicking. Secondary RBD is well described in association with neurological disorders including Parkinson's disease (PD), multiple system atrophy (MSA), and other conditions involving brainstem structures such as tumors. However, RBD alone is now considered to be a potential harbinger of later development of neurodegenerative disorders, in particular PD, MSA, dementia with Lewy bodies (DLB), and pure autonomic failure. These conditions are linked by their underpinning pathology of alpha-synuclein protein aggregation. In RBD, it is therefore important to recognize the potential risk for later development of an alpha-synucleinopathy, and to investigate for other potential causes such as medications. Other signs and symptoms have been described in RBD, such as orthostatic hypotension, or depression. While it is important to recognize these features to improve patient management, they may ultimately provide clinical clues that will lead to risk stratification for phenoconversion. A critical need is to improve our ability to counsel patients, particularly with regard to prognosis. The ability to identify who, of those with RBD, is at high risk for later neurodegenerative disorders will be paramount, and would in addition advance our understanding of the prodromal stages of the alpha-synucleinopathies. Moreover, recognition of at-risk individuals for neurodegenerative disorders may ultimately provide a platform for the testing of possible neuroprotective agents for these neurodegenerative disorders.

Accuracy of Rating Scales and Clinical Measures for Screening of Rapid Eye Movement Sleep Behavior Disorder and for Predicting Conversion to Parkinson's Disease and Other Synucleinopathies

Rapid eye movement (REM) sleep behavior disorder (RBD) is characterized by repeated episodes of REM sleep-related vocalizations and/or complex motor behaviors. Definite diagnosis of RBD is based on history and polysomnography, both of which are less accessible due to the lack of trained specialists and high cost. While RBD may be associated with disorders like narcolepsy, focal brain lesions, and encephalitis, idiopathic RBD (iRBD) may convert to Parkinson's disease (PD) and other synucleinopathies in more than 80% of patients and it is to date the most specific clinical prodromal marker of PD. Identification of individuals at high risk for development of PD is becoming one of the most important topics for current PD-related research as well as for future treatment trials targeting prodromal PD. Furthermore, concomitant clinical symptoms, such as subtle motor impairment, hyposmia, autonomic dysfunction, or cognitive difficulties, in subjects with iRBD may herald its phenoconversion to clinically manifest parkinsonism. The assessment of these motor and non-motor symptoms in iRBD may increase the sensitivity and specificity in identifying prodromal PD subjects. This review evaluates the diagnostic accuracy of individual rating scales and validated single items for screening of RBD and the role and accuracy of available clinical, electrophysiological, imaging, and tissue biomarkers in predicting the phenoconversion from iRBD to clinically manifest synucleinopathies.

Neuroprotection afforded by circadian regulation of intracellular glutathione levels: A key role for miRNAs

Circadian rhythms are approximately 24-h oscillations of physiological and behavioral processes that allow us to adapt to daily environmental cycles. Like many other biological functions, cellular redox status and antioxidative defense systems display circadian rhythmicity. In the central nervous system (CNS), glutathione (GSH) is a critical antioxidant because the CNS is extremely vulnerable to oxidative stress; oxidative stress, in turn, causes several fatal diseases, including neurodegenerative diseases. It has long been known that GSH level shows circadian rhythm, although the mechanism underlying GSH rhythm production has not been well-studied. Several lines of recent evidence indicate that the expression of antioxidant genes involved in GSH homeostasis as well as circadian clock genes are regulated by post-transcriptional regulator microRNA (miRNA), indicating that miRNA plays a key role in generating GSH rhythm. Interestingly, several reports have shown that alterations of miRNA expression as well as circadian rhythm have been known to link with various diseases related to oxidative stress. A growing body of evidence implicates a strong correlation between antioxidative defense, circadian rhythm and miRNA function, therefore, their dysfunctions could cause numerous diseases. It is hoped that continued elucidation of the antioxidative defense systems controlled by novel miRNA regulation under circadian control will advance the development of therapeutics for the diseases caused by oxidative stress.

Parkinson's Disease Dementia and Dementia with Lewy Bodies Have Similar Neuropsychological Profiles

Parkinson’s disease dementia (PDD) and dementia with Lewy bodies (DLB) are common causes of dementia worldwide. Although considered separate entities based on the relative temporal onset of motor symptoms vs. diagnosis of dementia, it is unknown if these diseases truly have distinct cognitive profiles. We hypothesized that patients divided into PDD and DLB categories strictly by temporal criteria would have different neuropsychological profiles. We investigated this question via neuropsychological testing of PDD and DLB patients at the University of Iowa. We performed retrospective chart analysis and review of neuropsychological testing of clinically diagnosed patients with PDD or DLB, who had presented to University of Iowa’s dementia and movement disorder clinics. Forty-seven patients diagnosed by the treating neurologist as PDD or DLB were included. Neuropsychological performance was compared between groups, and as a function of the relative timing of the motor diagnosis vs. diagnosis of dementia. We found that both PDD and DLB patients showed severe deficits in executive function, visual–spatial processing, and verbal learning. However, we found no significant differences in neuropsychological performance between groups, and neuropsychological performance could not reliably account for the relative timing of motor diagnosis vs. diagnosis of dementia. Our data support the idea that DLB and PDD are on a neuropsychological spectrum.

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.

The REM Sleep Behavior Disorder Screening Questionnaire: Validation Study of the Korean Version (RBDQ-KR)

STUDY OBJECTIVES

REM sleep behavior disorder (RBD) is a parasomnia that is commonly associated with neurodegenerative disorders. We aimed to validate the Hong Kong version of the self-reported RBD questionnaire (RBDQ-HK) with the Korean version (RBDQ-KR) and to investigate its clinical usefulness.

METHODS

One-hundred five patients with RBD and 105 age- and sex-matched controls were enrolled. Thirty were randomly selected for a retest with the questionnaire after 2 to 4 weeks without any treatment. Receiver operating characteristic curve and exploratory factor analysis were used to evaluate the scale, which had a score ranging from 0 to 100.

RESULTS

There was no difference in mean age and sex in patients with RBD and control subjects. Patients with RBD had a significantly higher total RBDQ-KR score than the control group (P < .001). The RBDQ-KR demonstrated high sensitivity (93.3%), specificity (89.5%), positive predictive value (89.9%), and negative predictive value (93.1%). Cronbach α coefficient for internal consistency of the total score of the RBDQ-KR was 0.9, which shows high reliability. Exploratory factor analysis showed two components, dream-related and behavioral factors, consistent with the main clinical features of RBD. Based on the results, the best cutoff for the total score ranging from 0 to 100 was at 18/19 and for factor 2 ranging from 0 to 75 was at 11.

CONCLUSIONS

This study showed RBDQ-KR is a valid and reliable questionnaire for RBD symptoms and severity in Korea. It serves as an effective tool to identify patients with RBD and to facilitate future clinical and research studies.

[Diagnostic of prodromal dementia with Levy bodies]

The issues of diagnosis of prodromal dementia with Lewy bodies are considered. Despite numerous studies using international diagnostic criteria, clinical and diagnosis are often inconsistent. Early and more accurate detection of dementia with Lewy bodies is needed for prognosis, optimal management and effective pharmacotherapy.

REM sleep behavior disorder, autonomic dysfunction and synuclein-related neurodegeneration: where do we stand?

INTRODUCTION

From newfound parasomnia to a marker of future synucleinopathy, since its first description in 1986, REM sleep behavior disorder (RBD) has been systematically tackled from virtually many viewpoints in basic, translational, and clinical studies. The time delay between RBD and synucleinopathy onset offers an exceptional window for observation and design of neuroprotective trials. In the last few years, research has focused on characterizing possible differences within RBD patients in order to draw potential profiles more or less susceptible to further neurodegeneration. Attention has been drawn towards autonomic dysfunction in RBD as one of such variables.

OVERVIEW

In this review, REM sleep physiology and relevant brain anatomy is briefly mentioned and integrated with neuroanatomical and physiological concepts regarding the central autonomic network. A detailed summary of works showing the presence of autonomic dysfunction in RBD is provided, and clinical and electrophysiological features of RBD in synucleinopathies are discussed. A short overview of RBD in other neurodegenerative diseases is also provided.

Impact of multiple pathologies on the threshold for clinically overt dementia

Longitudinal clinical-pathological studies have increasingly recognized the importance of mixed pathologies (the coexistence of one or more neurodegenerative and cerebrovascular disease pathologies) as important factors in the development of Alzheimer's disease (AD) and other forms of dementia. Older persons with AD pathology, often have concomitant cerebrovascular disease pathologies (macroinfarcts, microinfarcts, atherosclerosis, arteriolosclerosis, cerebral amyloid angiopathy) as well as other concomitant neurodegenerative disease pathologies (Lewy bodies, TDP-43, hippocampal sclerosis). These additional pathologies lower the threshold for clinical diagnosis of AD. Many of these findings from pathologic studies, especially for CVD, have been confirmed using sophisticated neuroimaging technologies. In vivo biomarker studies are necessary to provide an understanding of specific pathologic contributions and time course relationships along the spectrum of accumulating pathologies. In this review, we provide a clinical-pathological perspective on the role of multiple brain pathologies in dementia followed by a review of the available clinical and biomarker data on some of the mixed pathologies.

Brain Atrophy of Secondary REM-Sleep Behavior Disorder in Neurodegenerative Disease

BACKGROUND

Rapid eye movement sleep behavior disorder (RBD) may present as an early manifestation of an evolving neurodegenerative disorder with alpha-synucleinopathy.

OBJECTIVE

We investigated that dementia with RBD might show distinctive cortical atrophic patterns.

METHODS

A total of 31 patients with idiopathic Parkinson's disease (IPD), 23 with clinically probable Alzheimer's disease (AD), and 36 healthy controls participated in this study. Patients with AD and IPD were divided into two groups according to results of polysomnography and rated with a validated Korean version of the RBD screening questionnaire (RBDSQ-K), which covers the clinical features of RBD. Voxel-based morphometry was adapted for detection of regional brain atrophy among groups of subjects.

RESULTS

Scores on RBDSQ-K were higher in the IPD group (3.54 ± 2.8) than in any other group (AD, 2.94 ± 2.4; healthy controls, 2.31 ± 1.9). Atrophic changes according to RBDSQ-K scores were characteristically in the posterior part of the brain and brain stem, including the hypothalamus and posterior temporal region including the hippocampus and bilateral occipital lobe. AD patients with RBD showed more specialized atrophic patterns distributed in the posterior and inferior parts of the brain including the bilateral temporal and occipital cortices compared to groups without RBD. The IPD group with RBD showed right temporal cortical atrophic changes.

CONCLUSION

The group of patients with neurodegenerative diseases and RBD showed distinctive brain atrophy patterns, especially in the posterior and inferior cortices. These results suggest that patients diagnosed with clinically probable AD or IPD might have mixed pathologies including α-synucleinopathy.

Neuropathology of Nonmotor Symptoms of Parkinson's Disease

Parkinson's disease (PD), a multiorgan neurodegenerative disorder associated with α-synuclein deposits throughout the nervous system and many organs, is clinically characterized by motor and nonmotor features, many of the latter antedating motor dysfunctions by 20 or more years. The causes of the nonmotor manifestations such as olfactory, autonomic, sensory, neuropsychiatric, visuospatial, sleep, and other disorders are unlikely to be related to single lesions. They are mediated by the involvement of both dopaminergic and nondopaminergic systems, and diverse structures outside the nigrostriatal system that is mainly responsible for the motor features of PD. The nonmotor alterations appear in early/prodromal stages of the disease and its further progression, suggesting a topographical and chronological spread of the lesions. This lends further support for the notion that PD is a multiorgan proteinopathy, although the exact relationship between presymptomatic and later developing nonmotor features of PD and neuropathology awaits further elucidation.

Lewy Body Disorders

Dementia syndromes associated with Lewy bodies are subdivided into dementia with Lewy bodies (DLB), an underdiagnosed cause of dementia in the elderly, and Parkinson disease with dementia (PDD), cognitive impairment appearing in people diagnosed with Parkinson disease. Their neuropathologic substrates are the widespread distribution of aggregates of the protein α-synuclein in neurons in cortical brain regions, accompanied by variable Alzheimer pathology. Clinical features of DLB and PDD include distinctive changes in cognition, behavior, movement, sleep, and autonomic function. Diagnostic criteria for DLB and PDD incorporate these features. Current treatment options for DLB and PDD are symptomatic.

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.

Visual dysfunction in Parkinson's disease

Patients with Parkinson's disease have a number of specific visual disturbances. These include changes in colour vision and contrast sensitivity and difficulties with complex visual tasks such as mental rotation and emotion recognition. We review changes in visual function at each stage of visual processing from retinal deficits, including contrast sensitivity and colour vision deficits to higher cortical processing impairments such as object and motion processing and neglect. We consider changes in visual function in patients with common Parkinson's disease-associated genetic mutations including GBA and LRRK2 . We discuss the association between visual deficits and clinical features of Parkinson's disease such as rapid eye movement sleep behavioural disorder and the postural instability and gait disorder phenotype. We review the link between abnormal visual function and visual hallucinations, considering current models for mechanisms of visual hallucinations. Finally, we discuss the role of visuo-perceptual testing as a biomarker of disease and predictor of dementia in Parkinson's disease.

Treatment of REM Sleep Behavior Disorder

OPINION STATEMENT

REM sleep behavior disorder (RBD) is a common parasomnia disorder affecting between 1 and 7 % of community-dwelling adults, most frequently older adults. RBD is characterized by nocturnal complex motor behavior and polysomnographic REM sleep without atonia. RBD is strongly associated with synucleinopathy neurodegeneration. The approach to RBD management is currently twofold: symptomatic treatment to prevent injury and prognostic counseling and longitudinal follow-up surveillance for phenoconversion toward overt neurodegenerative disorders. The focus of this review is symptomatic treatment for injury prevention. Injury occurs in up to 55 % of patients prior to treatment, even when most behaviors seem to be infrequent or minor, so patients with RBD should be treated promptly following diagnosis to prevent injury risk. A sound evidence basis for symptomatic treatment of RBD remains lacking, and randomized controlled treatment trials are needed. Traditional therapeutic mainstays with relatively robust retrospective case series level evidence include melatonin and clonazepam, which appear to be equally effective, although melatonin is more tolerable. Melatonin also has one small randomized controlled crossover trial supporting its use for RBD treatment. Melatonin dosed 3-12 mg at bedtime should be considered as the first-line therapy, followed by clonazepam 0.25-2.0 mg at bedtime if initial melatonin is judged ineffective or intolerable. However, neither agent is likely to completely stop dream enactment behaviors, so choosing a moderate target dosage of melatonin 6 mg or clonazepam 0.5 mg, or the highest tolerable dosage that reduces attack frequency and avoids adverse effects from overtreatment, is currently the most reasonable strategy. Alternative second- and third-line therapies with anecdotal efficacy include temazepam, lorazepam, zolpidem, zopiclone, pramipexole, donepezil, ramelteon, agomelatine, cannabinoids, and sodium oxybate. A novel non-pharmacological approach is a bed alarm system, although this may be most useful in patients who also report sleep walking or a history of leaving their bed during dream enactment episodes. The benefit of hypnosis, especially in those with psychiatric RBD, also requires further study. RBD is an attractive target for future neuroprotective treatment trials to prevent evolution of overt parkinsonism or memory decline, but currently, there are no known effective treatments and future trials will be necessary to determine if RBD is an actionable time point in the evolution of overt synucleinopathy.

Rapid eye movement sleep behavior disorder in patients with probable Alzheimer's disease

BACKGROUND AND AIMS

Rapid eye movement (REM) sleep behavior disorder (RBD) is commonly associated with neurodegenerative disorders characterized by α-synuclein deposition, including Parkinson's disease, multiple system atrophy, and Lewy body dementia. However, this tendency in tauopathy-mediated diseases is rare and only sporadically reported. We systematically illustrate the occurrence of RBD and sleep features among a cohort of patients with Alzheimer's disease (AD), a non-synucleinopathy.

METHODS

We recruited 105 clinically probable AD patients. Fifteen clinically probable AD patients with suspected RBD underwent a video-polysomnography (vPSG) examination.

RESULTS

Five patients with probable AD exhibited RBD. One of the patients performed repeated touching of the head and the face with his hands and flailed his arms. Three patients exhibited hand twisting, exploring, prominent limb kicking, and jerking. The fifth patient exhibited all of the characteristics of RBD (he recalled a dream about fighting animals), and his wife was awakened by his screaming. Of these five patients, one patient took the acetylcholinesterase inhibitor drug donepezil. The patients with AD + RBD demonstrated increases in both tonic and phasic electromyography activity during REM sleep, but sleep architecture did not differ between the AD + RBD and AD-alone groups.

CONCLUSION

RBD can occur in patients with AD. The occurrence of RBD does not change the sleep architecture of AD patients.

Pramipexole in the treatment of REM sleep behaviour disorder: A critical review

While widely accepted as a first-line treatment for rapid eye movement sleep (REM) behaviour disorder, clonazepam (CNZP) has side effects that limit its applicability. Pramipexole is a possible alternative, but limited literature on its effectiveness exists. This review aims to summarize the available data on the use of pramipexole in REM sleep behaviour disorder. A systematic search of major databases was conducted to look for published and on-going trials. This search yielded a total of five articles, all of which are observational in nature. Factors associated with effectiveness include low doses (less than 1.5mg/day) and idiopathic rapid eye movement sleep behaviour disorder/absence of neurodegenerative disease. Overall, the evidence is inconclusive. This is due to the lack of randomised controlled trials and the challenges in interpreting polysomgraphy findings in rapid eye movement sleep behaviour disorder. Suggestions are given on how future trials evaluating pramipexole treatment in rapid eye movement sleep behaviour disorder could overcome current methodological issues in extant literature.

National validation and proposed revision of REM sleep behavior disorder screening questionnaire (RBDSQ)

We validated the Italian version of the rapid eye movement sleep behavior disorder (RBD) screening questionnaire (RBDSQ) and calculated its cut-off value for discriminating RBD group from other sleep disorders and healthy controls (HC). 380 patients with sleep disorders and 101 HC were enrolled. RBDSQ achieved an acceptable Cronbach's α value of 0.787 and item 10 was the only one with a very low item-total biserial correlation (0.141). At ROC analysis, we obtained an AUC of 0.888, denoting a good performance of the RBDSQ total score for predicting the RBD status. The optimal cut-off value was 8 and it achieved good values of both sensitivity and specificity (0.842 and 0.780, respectively). Due to the poor performance of item 10 in our sample, we analyzed the RBDSQ without this item (called "revised RBDSQ"). We obtained a good Cronbach's α of 0.802. When evaluating the performance of the revised score in predicting the RBD status, we obtained an increased value of AUC (0.899). The optimal cut-off value was still 8 (sensitivity = 0.829; specificity = 0.820). The Italian version of RBDSQ is a sensitive tool for the identification of RBD patients. An improvement of the instrument could be obtained by removing item 10 and define a higher cut-off value of 8. The "revised RBDSQ" represents a reliable screening questionnaire for primary care physicians and neurologists and its employment may facilitate the choice of subjects that should undergo a PSG that confirms the diagnosis of RBD, thus avoiding polysomnographic exams when not needed.

Revisiting DLB Diagnosis: A Consideration of Prodromal DLB and of the Diagnostic Overlap With Alzheimer Disease

Efforts to clinically diagnose cases having dementia with Lewy bodies (DLB) identify those with a characteristic clinical syndrome (probable DLB) at the expense of missing an equal, if not greater, number of cases who have atypical presentations thought to be associated with coexisting Alzheimer pathologies. This article argues that further efforts should now be made to characterize this atypical group that constitutes cases previously identified postmortem as the Lewy body variant of Alzheimer disease (AD) or as AD with Lewy bodies. Since such fine distinction is unlikely to be achieved on clinical grounds alone, this new diagnostic category will require robust biomarker validation. Turning to a consideration of early/prodromal diagnosis of both typical and atypical DLB cases, it is suggested that there will be at least 3 prototypical forms-a mild cognitive impairment variant, associated with early visuoperceptual and attentional deficits; a delirium onset DLB with provoked or spontaneous delirium as the presenting features; and a psychiatric disorder DLB with its primary presentation as a late-onset affective disorder or psychosis.

Sleep in Alzheimer's Disease - Beyond Amyloid

Sleep disorders are prevalent in Alzheimer's disease (AD) and a major cause of institutionalization. Like AD pathology, sleep abnormalities can appear years before cognitive decline and may be predictive of dementia. A bidirectional relationship between sleep and amyloid β (Aβ) has been well established with disturbed sleep and increased wakefulness leading to increased Aβ production and decreased Aβ clearance; whereas Aβ deposition is associated with increased wakefulness and sleep disturbances. Aβ fluctuates with the sleep-wake cycle and is higher during wakefulness and lower during sleep. This fluctuation is lost with Aβ deposition, likely due to its sequestration into amyloid plaques. As such, Aβ is believed to play a significant role in the development of sleep disturbances in the preclinical and clinical phases of AD. In addition to Aβ, the influence of tau AD pathology is likely important to the sleep disturbances observed in AD. Abnormal tau is the earliest observable AD-like pathology in the brain with abnormal tau phosphorylation in many sleep regulating regions such as the locus coeruleus, dorsal raphe, tuberomammillary nucleus, parabrachial nucleus, and basal forebrain prior to the appearance of amyloid or cortical tau pathology. Furthermore, human tau mouse models exhibit AD-like sleep disturbances and sleep changes are common in other tauopathies including frontotemporal dementia and progressive supranuclear palsy. Together these observations suggest that tau pathology can induce sleep disturbances and may play a large role in the sleep disruption seen in AD. To elucidate the relationship between sleep and AD it will be necessary to not only understand the role of amyloid but also tau and how these two pathologies, together with comorbid pathology such as alpha-synuclein, interact and affect sleep regulation in the brain.

Idiopathic rapid eye movement sleep behaviour disorder: diagnosis, management, and the need for neuroprotective interventions

Idiopathic rapid eye movement (REM) sleep behaviour disorder (IRBD) manifests as unpleasant dreams and vigorous behaviours during REM sleep that can result in injuries. Patients with IRBD have no known neurological diseases or motor or cognitive complaints; however, this sleep disorder is not harmless. In most cases, IRBD is the prelude of the synucleinopathies Parkinson's disease, dementia with Lewy bodies, or, less frequently, multiple system atrophy. Patients can show abnormalities that are characteristic of the synucleinopathies, and longitudinal follow-up shows that most patients develop parkinsonism and cognitive impairments with time. Thus, diagnosis of IRBD needs to be accurate and involves informing the patient of the risk of developing a neurodegenerative disease. It is extraordinary for a sleep disorder to precede the full expression of a neurodegenerative disease, which renders IRBD of particular interest in studies of the prodromal stage of the synucleinopathies, and in the development of neuroprotective interventions to stop or slow neurodegenerative deterioration before motor and cognitive symptomatology emerges. Such therapeutics do not currently exist, and thus represent an unmet need in IRBD.

Progression of cognitive impairments in idiopathic REM sleep behaviour disorder

BACKGROUND

Idiopathic REM (rapid eye movement) sleep behaviour disorder (iRBD) has been implicated in cognitive impairments, but there is little evidence about progression of cognitive dysfunction in iRBD.

METHODS

A retrospective follow-up study with patients with iRBD was performed. Conversion to neurodegenerative disorders was analysed by Kaplan-Meier survival analysis. Neuropsychological test results at baseline were compared between patients with iRBD and healthy controls. 57 patients with iRBD were successfully followed up for changes of cognitive performance over time (follow-up duration 50.84±25.38 months; range 12-108 months). Factors affecting cognitive decline were evaluated with multiple regression analysis and the subgroup analysis for groups with and without conversion was carried out.

RESULTS

Among 84 patients with iRBD, conversion occurred in 18 patients and conversion rates were estimated to be 9%, 18% and 35% at 3, 5 and 6 years from diagnosis of iRBD. Individuals with iRBD showed lower z-scores at baseline than controls in Mini-Mental Status Examination, Trail Making Test A, constructional praxis and Executive Clock Drawing Task (CLOX2). Patients with non-converting iRBD showed significant performance decline in memory (p=0.003, Digit span forward) and a worsening tendency of executive functions (p=0.007, frontal assessment battery; p=0.012, Stroop test) at follow-up tests. Cognitive decline was associated with disease duration or follow-up duration, and lower executive function at baseline increased conversion risk (p=0.031).

CONCLUSIONS

Patients with iRBD have cognitive impairments at baseline and progressive cognitive decline over time. Even in idiopathic cases without development of any neurodegenerative disease, degenerative changes in cognition seem to be under way.