Physiological and anatomical link between Parkinson-like disease and REM sleep behavior disorder

Current Treatments and New, Tentative Therapies for Parkinson’s Disease

Parkinson’s disease (PD) is a neurodegenerative pathology, the origin of which is associated with the death of neuronal cells involved in the production of dopamine. The prevalence of PD has increased exponentially. The aim of this review was to describe the novel treatments for PD that are currently under investigation and study and the possible therapeutic targets. The pathophysiology of this disease is based on the formation of alpha-synuclein folds that generate Lewy bodies, which are cytotoxic and reduce dopamine levels. Most pharmacological treatments for PD target alpha-synuclein to reduce the symptoms. These include treatments aimed at reducing the accumulation of alpha-synuclein (epigallocatechin), reducing its clearance via immunotherapy, inhibiting LRRK2, and upregulating cerebrosidase (ambroxol). Parkinson’s disease continues to be a pathology of unknown origin that generates a significant social cost for the patients who suffer from it. Although there is still no definitive cure for this disease at present, there are numerous treatments available aimed at reducing the symptomatology of PD in addition to other therapeutic alternatives that are still under investigation. However, the therapeutic approach to this pathology should include a combination of pharmacological and non-pharmacological strategies to maximise outcomes and improve symptomatological control in these patients. It is therefore necessary to delve deeper into the pathophysiology of the disease in order to improve these treatments and therefore the quality of life of the patients.

Convergent patterns of structural brain changes in rapid eye movement sleep behavior disorder and Parkinson's disease on behalf of the German rapid eye movement sleep behavior disorder study group

STUDY OBJECTIVES

Rapid eye movement sleep behavior disorder (RBD) is considered a prodromal state of Parkinson's disease (PD). We aimed to characterize patterns of structural brain changes in RBD and PD patients using multimodal MRI.

METHODS

A total of 30 patients with isolated RBD, 29 patients with PD, and 56 age-matched healthy controls (HC) underwent MRI at 3T, including tensor-based morphometry, diffusion tensor imaging, and assessment of cortical thickness.

RESULTS

RBD individuals showed increased volume of the right caudate nucleus compared with HC, and higher cerebellar volume compared with both PD subjects and HC. Similar to PD subjects, RBD patients displayed increased fractional anisotropy (FA) in the corticospinal tracts, several tracts mainly related to non-motor function, and reduced FA of the corpus callosum compared with HC. Further, RBD subjects showed higher FA in the cerebellar peduncles and brainstem compared with both, PD patients and HC. PD individuals exhibited lower than normal volume in the basal ganglia, midbrain, pedunculopontine nuclei, and cerebellum. In contrast, volume in PD subjects was increased in the thalamus compared with both HC and RBD subjects.

CONCLUSIONS

We found convergent patterns of structural brain alterations in RBD and PD patients compared with HC. The changes observed suggest a co-occurrence of neurodegeneration and compensatory mechanisms that fail with emerging PD pathology. Our findings strengthen the hypothesis of RBD and PD constituting a continuous disease spectrum.

Sleep Disorders in Parkinson Disease

Sleep disorders in Parkinson disease have attracted the attention of clinicians and researchers for decades. Recently, major advances in their clinical characterization, polysomnographic description, pathophysiologic understanding, and treatment took place. Parkinson disease encompasses the whole spectrum of sleep medicine: every category of sleep disorder can be observed in these patients. Video polysomnography frequently is indicated, sometimes followed by multiple sleep latency/maintenance of wakefulness tests. Additional studies may include actigraphy, cardiorespiratory polygraphy, and dim light melatonin assessment. Treatment needs to be specific to the underlying sleep disorder and can include medications and nondrug treatments, for example, behavioral therapy and light therapy.

Association Between Amyloid Accumulation and Sleep in Patients With Idiopathic REM Sleep Behavior Disorder

Background and Objectives: Amyloid-beta protein may lead to sleep disturbance and eventually develop cognitive impairment. Idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD) is a predictor of neurodegeneration, yet there have been limited studies evaluating the relationship between cognitive decline and amyloid accumulation in iRBD patients. The aim of this study is to investigate the clinical and sleep characteristics of iRBD patients and its association with amyloid deposition.

Methods: We enroll 23 iRBD patients (mean age, 65.8 years; male, 73.9%), and their mean history of clinically suspected RBD was 6.5 years. All underwent 18F-flutemetamol amyloid PET completed polysomnography (PSG) and questionnaires. Patients were classified into two groups according to amyloid deposition as amyloid positive and negative. Clinical and sleep parameters were compared between groups and were correlated with amyloid deposition, calculated as a standardized uptake value ratio (SUVR).

Results: Four patients (17.4%) were revealed to be amyloid positive, and they showed increased percentage of wake after sleep onset (WASO), stage N1, and stage N2 sleep and worse on the Stroop Word Color Test compared to amyloid negative patients. Global SUVR was correlated with total sleep time, sleep efficiency, WASO, and N1 sleep, and these sleep parameters were associated with a part of default mode network of brains such as orbitofrontal, dorsolateral pre-frontal, and left temporal areas.

Conclusion: iRBD patients with amyloid deposition have worse sleep quality than patients without amyloid. Relationship between fragmented sleep and amyloid deposition in the default mode network may be crucial to elucidate the disease progress of iRBD.

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.

Sleep in the Elderly

Aging is associated with several changes in sleep patterns. Older adults have increased prevalence of primary sleep disorders including insomnia, sleep disordered breathing, restless legs syndrome, REM sleep behavior disorder, and circadian rhythm disturbances. These can be further compromised by sleep disturbances secondary to medical or psychiatric disorders, and medication side effects. This review discusses age-related changes in sleep architecture, etiology, clinical presentation, and treatment options of various sleep disorders in the elderly.

Idiopathic REM sleep behaviour disorder and neurodegeneration - an update

So-called idiopathic rapid eye movement (REM) sleep behaviour disorder (RBD), formerly seen as a rare parasomnia, is now recognized as the prodromal stage of an α-synucleinopathy. Given the very high risk that patients with idiopathic RBD have of developing α-synucleinopathies, such as Parkinson disease (PD), PD dementia, dementia with Lewy bodies or multiple system atrophy, and the outstandingly high specificity and very long interval between the onset of idiopathic RBD and the clinical manifestations of α-synucleinopathies, the prodromal phase of this disorder represents a unique opportunity for potentially disease-modifying intervention. This Review provides an update on classic and novel biomarkers of α-synuclein-related neurodegeneration in patients with idiopathic RBD, focusing on advances in imaging and neurophysiological, cognitive, autonomic, tissue-specific and other biomarkers. We discuss the strengths, potential weaknesses and suitability of these biomarkers for identifying RBD and neurodegeneration, with an emphasis on predicting progression to overt α-synucleinopathy. The role of video polysomnography in providing quantifiable and potentially treatment-responsive biomarkers of neurodegeneration is highlighted. In light of all these advances, and the now understood role of idiopathic RBD as an early manifestation of α-synuclein disease, we call for idiopathic RBD to be reconceptualized as isolated RBD.

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.

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.

(123)I-Metaiodobenzylguanidine Myocardial Scintigraphy in Lewy Body-Related Disorders: A Literature Review

Lewy body-related disorders are characterized by the presence of Lewy bodies and Lewy neurites, which have abnormal aggregations of α-synuclein in the nigral and extranigral areas, including in the heart. ¹²³I-metaiodobenzylguanidine (MIBG) scintigraphy is a well-known tool to evaluate cardiac sympathetic denervation in the Lewy body-related disorders. MIBG scintigraphy showed low uptake of MIBG in the Lewy body-related disorders, including Parkinson’s disease, dementia with Lewy bodies, pure autonomic failure and rapid eye movement sleep behavior disorder. This review summarizes previous results on the diagnostic applications of MIBG scintigraphy in Lewy body-related disorders.

Evidence that adrenergic ventrolateral medullary cells are activated whereas precerebellar lateral reticular nucleus neurons are suppressed during REM sleep

Rapid eye movement sleep (REMS) is generated in the brainstem by a distributed network of neurochemically distinct neurons. In the pons, the main subtypes are cholinergic and glutamatergic REMS-on cells and aminergic REMS-off cells. Pontine REMS-on cells send axons to the ventrolateral medulla (VLM), but little is known about REMS-related activity of VLM cells. In urethane-anesthetized rats, dorsomedial pontine injections of carbachol trigger REMS-like episodes that include cortical and hippocampal activation and suppression of motoneuronal activity; the episodes last 4–8 min and can be elicited repeatedly. We used this model to determine whether VLM catecholaminergic cells are silenced during REMS, as is typical of most aminergic neurons studied to date, and to investigate other REMS-related cells in this region. In 18 anesthetized, paralyzed and artificially ventilated rats, we obtained extracellular recordings from VLM cells when REMS-like episodes were elicited by pontine carbachol injections (10 mM, 10 nl). One major group were the cells that were activated during the episodes (n = 10). Their baseline firing rate of 3.7±2.1 (SD) Hz increased to 9.7±2.1 Hz. Most were found in the adrenergic C1 region and at sites located less than 50 µm from dopamine β-hydroxylase-positive (DBH⁺) neurons. Another major group were the silenced or suppressed cells (n = 35). Most were localized in the lateral reticular nucleus (LRN) and distantly from any DBH⁺ cells. Their baseline firing rates were 6.8±4.4 Hz and 15.8±7.1 Hz, respectively, with the activity of the latter reduced to 7.4±3.8 Hz. We conclude that, in contrast to the pontine noradrenergic cells that are silenced during REMS, medullary adrenergic C1 neurons, many of which drive the sympathetic output, are activated. Our data also show that afferent input transmitted to the cerebellum through the LRN is attenuated during REMS. This may distort the spatial representation of body position during REMS.

From bench to bed: putative animal models of REM sleep behavior disorder (RBD)

REM behavior disorder (RBD) is a parasomnia characterized by REM sleep without atonia, leading to abnormal and potentially injurious behavior during REM sleep. It is considered one of the most specific predictors of neurodegenerative disorders, such as Parkinson's disease. In this paper, we provide an overview of animal models contributing to our current understanding of REM-associated atonia, and, as a consequence, the pathophysiology of RBD. The generator of REM-associated atonia is located in glutamatergic neurons of the pontine sublaterodorsal nucleus (SLD), as shown in cats, rats and mice. These findings are supported by clinical cases of patients with lesions of the homologous structure in humans. Glutamatergic SLD neurons, presumably in conjunction with others, project to (a) the ventromedial medulla, where they either directly target inhibitory interneurons to alpha motor neurons or are relayed, and (b) the spinal cord directly. At the spinal level, alpha motor neurons are inhibited by GABAergic and glycinergic interneurons. Our current understanding is that lesions of the glutamatergic SLD are the key factor for REM sleep behavior disorder. However, open questions remain, e.g. other features of RBD (such as the typically aggressive dream content) or the frequent progression from idiopathic RBD to neurodegenerative disorders, to name only a few. In order to elucidate these questions, a constant interaction between basic and clinical researchers is required, which might, ultimately, create an early therapeutic window for neurodegenerative disorders.

Parasomnias: an updated review

Parasomnias are abnormal behaviors emanating from or associated with sleep. Sleepwalking and related disorders result from an incomplete dissociation of wakefulness from nonrapid eye movement (NREM) sleep. Conditions that provoke repeated cortical arousals, or promote sleep inertia lead to NREM parasomnias by impairing normal arousal mechanisms. Changes in the cyclic alternating pattern, a biomarker of arousal instability in NREM sleep, are noted in sleepwalking disorders. Sleep-related eating disorder (SRED) is characterized by a disruption of the nocturnal fast with episodes of feeding after an arousal from sleep. SRED is often associated with the use of sedative-hypnotic medications; in particular, the widely prescribed benzodiazepine receptor agonists. Recently, compelling evidence suggests that nocturnal eating may in some cases be a nonmotor manifestation of Restless Legs Syndrome (RLS). rapid eye movement (REM) Sleep Behavior Disorder (RBD) is characterized by a loss of REM paralysis leading to potentially injurious dream enactment. The loss of atonia in RBD often predates the development of Parkinson's disease and other disorders of synuclein pathology. Parasomnia behaviors are related to an activation (in NREM parasomnias) or a disinhibition (in RBD) of central pattern generators (CPGs). Initial management should focus on decreasing the potential for sleep-related injury followed by treating comorbid sleep disorders. Clonazepam and melatonin appear to be effective therapies in RBD, whereas paroxetine has been reported effective in some cases of sleep terrors. At this point, pharmacotherapy for other parasomnias is less certain, and further investigations are necessary.

Recent data on rapid eye movement sleep behavior disorder in patients with Parkinson disease: analysis of behaviors, movements, and periodic limb movements

Rapid eye movement (REM) sleep behavior disorder (RBD) is a fascinating parasomnia in which patients are able to enact their dreams because of a lack of muscle atonia during REM sleep. RBD represents a unique window into the dream world. Frequently associated with Parkinson's disease (PD), RBD raises various issues about dream modifications in this pathology and about aggressiveness during RBD episodes in placid patients during wakefulness. Studies on these behaviors have underlined their non-stereotyped, action-filled and violent characteristics but also their isomorphism with dream content. Complex, learnt behaviors may reflect the cortical involvement in this parasomnia but the more frequent elementary movements and the associated periodic limb movements during sleep also implicate the brainstem. Surprisingly, patients with PD have an improvement of their movements during their RBD as if they were disease-free. Also not yet understood, this improvement of movement during REM sleep raises issues about the pathways involved in RBD and about the possibility of using this pathway to improve movement in PD during the day.

Postmortem studies in Parkinson's disease

No animal model to date perfectly replicates Parkinson's disease (PD) etiopathogenesis, and the anatomical organization of the nigrostriatal system differs considerably between species. Human postmortem material therefore remains the gold standard for both formulating hypotheses for subsequent testing in in vitro and in vivo PD models and verifying hypotheses derived from experimental PD models with regard to their validity in the human disease. This article focuses on recent and relevant fields in which human postmortem work has generated significant impact in our understanding of PD. These fields include Lewy body formation, regional vulnerability of dopaminergic neurons, oxidative/nitrative cellular stress, inflammation, apoptosis, infectious and environmental agents, and nondopaminergic lesions.

Sleep-related problems in neurologic diseases

There is a strong association between sleep-related problems and neurologic diseases. Neurologic diseases of the CNS can directly cause sleep problems when sleep-wake mechanisms associated with the ascending reticular activating system are involved. The major sleep disorders associated with neurologic problems are outlined in the International Classification of Sleep Disorders, 2nd edition, as hypersomnias of central origin, sleep-related breathing disorders, the insomnias, circadian rhythm sleep disorders, sleep-related movement disorders, parasomnias, and sleep-related epilepsy. In a patient with CNS disease and excessive sleepiness, sleep-related breathing disorders should be a first concern, given the known association between obstructive sleep apnea (OSA) and cerebrovascular disease and the potential confounding effects that OSA might have on an otherwise compromised ischemic CNS penumbra. A basic knowledge of the anatomy and physiology of the sleep-wake mechanisms provides a rationale for pharmacologic intervention. Nonpharmacologic treatments are also important, especially when sleep-related breathing disorders are a concern. In addition, as patients with neurologic diseases are often prone to the adverse effects of many medications, the specific treatment regimen for any given individual should always include good sleep hygiene practices that use cognitive behavioral therapy.

Sleep problems in Parkinson’s disease patients

SUMMARY Parkinson’s disease (PD) patients demonstrate a variety of sleep/wake complaints. Some of these are associated with dopaminergic dysfunction, some presumed to arise from nondopaminergic PD pathology, some from PD treatments and, in some, the etiologies are multifactorial or unknown. Optimal management of sleep/wake problems requires a good understanding of sleep/wake principals in the PD population, as there are few controlled trials to dictate therapy. In this article, we review the main causes of sleep/wake disorders in PD patients, namely sleep fragmentation, excessive daytime sleepiness, restless legs syndrome, periodic limb movement of sleep, rapid eye movement sleep behavioral disorder and sleep apnea. Available therapies and management recommendations for each disorder are given particular emphasis.

Neuropathology of non-motor features of Parkinson disease

Non-motor manifestations of Parkinson disease (PD) are common and some may actually antedate motor dysfunction. Extrapyramidal signs in PD are tightly linked to striatonigral dopaminergic denervation associated with neuronal loss and Lewy bodies in the residual neurons of the substantia nigra. Lewy bodies composed of abnormal alpha-synuclein are the histologic hallmark of PD, and their presence beyond midbrain dopaminergic neurons is considered to be the pathologic substrate of many, if not all, of the non-motor manifestations of PD. We review the pathologic correlates of autonomic dysfunction (cardiac and gastrointestinal), hyposmia, depression, rapid eye movement behavior disorder and dementia in PD For each non-motor clinical feature there is strong evidence to suggest a role for alpha-synuclein pathology, lending further support for the notion that PD is a multisystem alpha-synucleinopathy.

Multimodal sensory responses of nucleus reticularis gigantocellularis and the responses' relation to cortical and motor activation

The connectivity of large neurons of the nucleus reticularis gigantocellularis (NRGc) in the medullary reticular formation potentially allows both for the integration of stimuli, in several modalities, that would demand immediate action, and for coordinated activation of cortical and motoric activity. We have simultaneously recorded cortical local field potentials, neck muscle electromyograph (EMG), and the neural activity of medullary NRGc neurons in unrestrained, unanesthetized rats to determine whether the activity of the NRGc is consistent with the modulation of general arousal. We observed excitatory responses of individual NRGc neurons to all modalities tested: tactile, visual, auditory, vestibular, and olfactory. Excitation was directly linked to increases in neck muscle EMG amplitude and corresponded with increases in the power of fast oscillations (30 to 80 Hz) of cortical activity and decreases in the power of slow oscillations (2 to 8 Hz). Because these reticular formation neurons can respond to broad ranges of stimuli with increased firing rates associated with the initiation of behavioral responses, we infer that they are part of an elementary "first responder" CNS arousal mechanism.

Frequent nocturnal vocalization in pure autonomic failure

Nocturnal vocalization is frequent in Parkinson's disease patients with rapid eye movement (REM) sleep behaviour disorder (RBD). We investigated the frequency of nocturnal vocalization and other sleep problems in patients with pure autonomic failure (PAF) and compared the results with idiopathic Parkinson's disease (IPD) and dementia with Lewy bodies (DLB). We interviewed consecutive patient-caregiver pairs with PAF (n = 13), IPD (n = 200) and DLB (n = 19), and ischaemic stroke patients (controls, n = 43). Nocturnal vocalization was similarly frequent in PAF, IPD and DLB. Other dream enactments and vivid dreams also were more frequent in PAF, IPD and DLB compared with controls. Excessive night-time awakenings and daytime sleepiness were frequent in IPD but rare in PAF and controls. Clinical manifestation of sleep disturbances, at least of RBD-like symptoms including nocturnal vocalization and other dream enactments, may occur in PAF, as in IPD and DLB.

123I-MIBG cardiac scintigraphy provides clues to the underlying neurodegenerative disorder in idiopathic REM sleep behavior disorder

OBJECTIVE

RBD is considered to be a manifestation of an evolving synucleinopathy, such as Parkinson disease (PD), dementia of Lewy bodies (DLB), and multiple system atrophy (MSA). We tested whether the degree of accumulation of cardiac 123I-MIBG scintigraphy can distinguish the clinical syndromes associated with Lewy body-related disease from the syndrome of PSP (a tauopathy) and MSA.

DESIGN

Cross-sectional.

SETTING

University-based sleep disorders laboratory.

PATIENTS

Subjects comprised 95 patients (31, idiopathic RBD; 26, PD; 10, MSA; 6, DLB; 13, progressive supranuclear palsy [PSP]) and 9 control subjects.

INTERVENTION

To compare tracer uptake of cardiac 123I-MIBG between idiopathic RBD, PD, MSA, DLB, and PSP and control subjects.

MEASUREMENTS AND RESULTS

Cardiac 123I-MIBG accumulation was evaluated by the heart/mediastinum (H/M) ratio. Mean value of the H/M ratio (early, delayed) was significantly reduced in patients with idiopathic RBD compared to MSA patients, PSP patients, control subjects (P < 0.001 in each group) and PD patients in early images (P < 0.05). There was a correlation between the H/M ratio and disease duration in the idiopathic RBD group. ROC analysis revealed that an H/M cut-off value of 1.9 was useful for differentiating RBD from MSA and PSP as well as distinguishing control subjects from those with RBD in both early and delayed images.

CONCLUSION

Cardiac 123I-MIBG findings are similar among idiopathic RBD and the syndromes of PD and DLB, but differ from those of PSP and MSA.

Learning and consolidation of visuo-motor adaptation in Parkinson's disease

We have previously shown in normal subjects that motor adaptation to imposed visual rotation is significantly enhanced when tested few days later. This occurs through a process of sleep-dependent memory consolidation. Here we ascertained whether patients with Parkinson's disease (PD) learn, improve, and retain new motor skills in the same way as normal subjects. We tested 16 patients in early stages of PD and 21 control subjects over two days. All subjects performed reaching movements on a digitizing tablet. Vision of the limb was precluded with an opaque screen; hand paths were shown on the screen with the targets' position. Unbeknownst to the subjects, the hand path on the screen was rotated by 30 degrees . In experiment 1, patients taking dopaminergic treatment and controls adapted to rotation with targets appearing in an unpredictable order. In experiment 2, drug-naïve patients and controls adapted to rotation in a less challenging task where target's appearance was predictable. Patients and controls made similar movements and adapted to rotation in the same way. However, when tested again over the following days, controls' performance significantly improved compared to training, while patients' performance did not. This lack of consolidation, which is present in the early stages of the disease and is independent from therapy, may be due to abnormal homeostatic processes that occur during sleep.

Neurotoxic lesions at the ventral mesopontine junction change sleep time and muscle activity during sleep: an animal model of motor disorders in sleep

There is no adequate animal model of restless legs syndrome (RLS) and periodic leg movements disorder (PLMD), disorders affecting 10% of the population. Similarly, there is no model of rapid eye movement (REM) sleep behavior disorder (RBD) that explains its symptoms and its link to Parkinsonism. We previously reported that the motor inhibitory system in the brainstem extends from the medulla to the ventral mesopontine junction (VMPJ). We now examine the effects of damage to the VMPJ in the cat. Based on the lesion sites and the changes in sleep pattern and behavior, we saw three distinct syndromes resulting from such lesions; the rostrolateral, rostromedial and caudal VMPJ syndromes. The change in sleep pattern was dependent on the lesion site, but was not significantly correlated with the number of dopaminergic neurons lost. An increase in wakefulness and a decrease in slow wave sleep (SWS) and REM sleep were seen in the rostrolateral VMPJ-lesioned animals. In contrast, the sleep pattern was not significantly changed in the rostromedial and caudal VMPJ-lesioned animals. All three groups of animals showed a significant increase in periodic and isolated leg movements in SWS and increased tonic muscle activity in REM sleep. Beyond these common symptoms, an increase in phasic motor activity in REM sleep, resembling that seen in human RBD, was found in the caudal VMPJ-lesioned animals. In contrast, the increase in motor activity in SWS in rostral VMPJ-lesioned animals is similar to that seen in human RLS/PLMD patients. The proximity of the VMPJ region to the substantia nigra suggests that the link between RLS/PLMD and Parkinsonism, as well as the progression from RBD to Parkinsonism may be mediated by the spread of damage from the regions identified here into the substantia nigra.

Quantification of tonic and phasic muscle activity in REM sleep behavior disorder

REM sleep behavior disorder (RBD) is characterized by excessive tone of the chin muscle and limb movement during sleep. In the past, quantification of increased muscle tone in REM sleep has been performed visually, using no stringent criteria. The aim of this study was to develop an automatic analysis, allowing the quantification of muscle activity and its amplitude for all sleep stages, with a focus on REM sleep in patients with RBD. Forty-eight patients (27 male, 21 female) with RBD were included in the analysis. Twenty-one had idiopathic RBD; 28 had narcolepsy plus RBD. Twenty-five patients without confirmed sleep disorder served as control subjects. The amplitude of the EMG was generated from the difference of the upper and lower envelope of the mentalis muscle recordings. By smoothing the amplitude curve, a threshold curve was defined. Any muscle activity beyond the threshold curve was defined as motor activity. The means of the motor activity per second were summarized statistically and calculated for each sleep stage. Due to variable distribution of REM sleep, the latter was assigned to respective quartiles of the recorded night. Muscle activity was defined according to a histogram as short-lasting (<0.5 second) and long-lasting (>0.5 second) activity. No difference in the distribution of REM sleep/quartile and mean muscle tone throughout the sleep cycle could be found within the RBD groups and control subjects. Muscle activity was in the range of 200 ms. No clusters or regular distribution of muscle activity were found. Long muscle activity in the group with manifest clinical RBD was significantly higher than in control subjects, whereas it was nonsignificantly higher in subclinical RBD. The correlation between the frequency of long muscle activity in REM sleep and age was highly significant only for patients with idiopathic RBD. Automatic analysis of muscle activity in sleep is a reliable, easy method that may easily be used in the evaluation for REM sleep behavior disorder, creating indices of muscle activity similar to the indices for sleep apnea or PLMS. Together with the overt behavior, the analyses provides an important tool to get a deeper insight into the pathophysiology of RBD. Long movements appear to represent the motor disinhibition in REM sleep more distinct than short movements. The positive correlation of age and increased motor activity in REM sleep in idiopathic RBD highlights the idea of age dependant motor disinhibition as a continuum of a neurodegenerative disorder, which in narcolepsy patients with RBD only seems to happen as a single temporal event at onset of the disorder.

Sleep disorders in Parkinson's disease: an overview

Sleep disturbances are one of the most common of the nonmotor complications of Parkinson's disease (PD), and increase in frequency with advancing disease. The causes of sleep disturbance in PD are numerous, and many patients may have several factors that contribute. These disorders can be broadly categorized into those that involve nocturnal sleep and daytime manifestations such as excessive daytime sleepiness. Some sleep disorders, in particular REM sleep behavior disorder (RBD) and excessive daytime sleepiness (EDS) may arise as a primary manifestation of PD, reflecting the anatomic areas affected by the neurodegenerative process. Appropriate diagnosis of the sleep disturbance affecting a PD patient can lead to specific treatments that can consolidate nocturnal sleep and enhance daytime alertness.

Is REM sleep behaviour disorder (RBD) a risk factor of dementia in idiopathic Parkinson's disease?

OBJECTIVE

To study the sequence of occurrence of REM-sleep behaviour disorder (RBD) and dementia and their frequency among a population of patients with idiopathic Parkinson's disease (PD).

METHODS

We performed a cross-sectional study on 65 PD patients seen in a movement disorder clinic and their bed partner, and asked them to complete the validated Mayo Sleep Questionnaire for RBD and sleep disorders. The diagnosis of PD with dementia (PD-D) was based on a clinical diagnosis of dementia; following DSM-IV criteria and MMSE score less than 25 and a battery of cognitive tests.

RESULTS

From the 65 patients that completed the study, twenty-four met the clinical diagnosis of RBD. Ten of the 24 (42%) RBD patients met the clinical criteria of PD-D, whereas the remaining 14 patients were non-demented at the time of the study. The frequency of RBD was significantly higher in the PD-D group (n = 10, 77%) compared to the PD-ND group (n = 14, 27%, chi squared test: p = 0.0008). PD non-RBD had a lower occurrence of dementia (7.3%, 3 of 41) compared to those suffering from RBD (42%, 10 of 24). Of the 65 PD patients, 13 were diagnosed with PD-D and the remaining 52 were non-demented PD (PD-ND) patients. PD with RBD showed a faster decline in the number of dementia-free patients compared to the non-RBD patients (Log Rank test: p < 0.001). RBD preceded, coincided or followed the onset of the motor symptoms.

CONCLUSION

This study shows that RBD and dementia have a significant coincidence in the course of PD, and RBD not only precedes or coincides with the motor signs, but can occur during the course of the progression of the PD, suggesting a degenerative process of the dopaminergic and cholinergic neurons of the brainstem nuclei, progressing at a different pace in each patient.

Dementia with Lewy bodies

The advent of new immunostains have improved the ability to detect limbic and cortical Lewy bodies, and it is evident that dementia with Lewy bodies (DLB) is the second most common neurodegenerative dementia, after Alzheimer's disease (AD). Distinguishing DLB from AD has important implications for treatment, in terms of substances that may worsen symptoms and those that may improve them. Neurocognitive patterns, psychiatric features, extrapyramidal signs, and sleep disturbance are helpful in differentiating DLB from AD early in the disease course. Differences in the severity of cholinergic depletion and type/distribution of neuropathology contribute to these clinical differences.

Video analysis of motor events in REM sleep behavior disorder

In REM sleep behavior disorder (RBD), several studies focused on electromyographic characterization of motor activity, whereas video analysis has remained more general. The aim of this study was to undertake a detailed and systematic video analysis. Nine polysomnographic records from 5 Parkinson patients with RBD were analyzed and compared with sex- and age-matched controls. Each motor event in the video during REM sleep was classified according to duration, type of movement, and topographical distribution. In RBD, a mean of 54 +/- 23.2 events/10 minutes of REM sleep (total 1392) were identified and visually analyzed. Seventy-five percent of all motor events lasted <2 seconds. Of these events, 1,155 (83.0%) were classified as elementary, 188 (13.5%) as complex behaviors, 50 (3.6%) as violent, and 146 (10.5%) as vocalizations. In the control group, 3.6 +/- 2.3 events/10 minutes (total 264) of predominantly elementary simple character (n = 240, 90.9%) were identified. Number and types of motor events differed significantly between patients and controls (P < 0.05). This study shows a very high number and great variety of motor events during REM sleep in symptomatic RBD. However, most motor events are minor, and violent episodes represent only a small fraction.

Prominent burst firing of dopaminergic neurons in the ventral tegmental area during paradoxical sleep

Dopamine is involved in motivation, memory, and reward processing. However, it is not clear whether the activity of dopamine neurons is related or not to vigilance states. Using unit recordings in unanesthetized head restrained rats we measured the firing pattern of dopamine neurons of the ventral tegmental area across the sleep-wake cycle. We found these cells were activated during paradoxical sleep (PS) via a clear switch to a prominent bursting pattern, which is known to induce large synaptic dopamine release. This activation during PS was similar to the activity measured during the consumption of palatable food. Thus, as it does during waking in response to novelty and reward, dopamine could modulate brain plasticity and thus participate in memory consolidation during PS. By challenging the traditional view that dopamine is the only aminergic group not involved in sleep physiology, this study provides an alternative perspective that may be crucial for understanding the physiological function of PS and dream mentation.

Sleep and aging: 1. Sleep disorders commonly found in older people

Aging is associated with several well-described changes in patterns of sleep. Typically, there is a phase advance in the normal circadian sleep cycle: older people tend to go to sleep earlier in the evening but also to wake earlier. They may also wake more frequently during the night and experience fragmented sleep. The prevalence of many sleep disorders increases with age. Insomnia, whether primary or secondary to coexistant illness or medication use, is very common among elderly people. Rapid eye movement (REM) sleep behaviour disorder and narcolepsy, although less common, are frequently not considered for this population. Periodic leg-movement disorder, a frequent cause of interrupted sleep, can be easily diagnosed with electromyography during nocturnal polysomnography. Restless legs syndrome, however, is diagnosed clinically. Snoring is a common sleep-related respiratory disorder; so is obstructive sleep apnea, which is increasingly seen among older people and is significantly associated with cardio-and cerebrovascular disease as well as cognitive impairment.

Pathophysiologic mechanisms in REM sleep behavior disorder

REM sleep behavior disorder (RBD) is a fascinating experiment in nature predicted by animal studies in 1964. A defining feature of REM sleep is active paralysis of all somatic musculature (sparing the diaphragm to permit respiration). RBD is characterized by the absence of REM atonia, permitting the appearance of dream-enacting behaviors. These oneiric behaviors may be violent or injurious. RBD typically affects men over the age of 50 years. Longitudinal follow-up has shown that the majority of individuals with RBD will eventually develop additional signs and symptoms of a number of neurodegenerative disorders, most notably one of the synucleinopathies (Parkinson's disease, dementia with Lewy body disease, multiple system atrophy, or pure autonomic failure), often after a prolonged interval lasting more than 10 years. RBD is also a common manifestation of narcolepsy. RBD may be induced by medications, especially the tricyclic antidepressants and serotonin-specific reuptake inhibitors. In most cases, clonazepam is a highly effective treatment.

Manipulation of proliferation and differentiation of human bone marrow-derived neural stem cells in vitro and in vivo

Recent evidence has demonstrated that neural stem cells (NSC) can be expanded from a variety of sources, including embryos, fetuses, and adult bone marrow and brain tissue. We have previously reported the generation of adult rat bone marrow-derived cellular spheres that are morphologically and phenotypically similar to neurospheres derived from brain NSC. Here we show that adult human bone marrow-derived neural stem cells (HBM-NSC) are capable of generating spheres that are similar to brain neural-derived neurospheres. Additionally, we sought to promote proliferation and differentiation of HBM-NSC through transduction with nonreplicative recombinant adenovirus encoding the cDNA sequence for Gli, rADV-Gli-1; sonic hedgehog, rADV-Shh; or Nurr1, rADV-Nurr1. Immunocytochemistry and RT-PCR analysis showed that HBM-NSC could be efficiently expanded and differentiated in vitro and that HBM-NSC transduced with rADV-Gli-1 or rADV-Shh dramatically increased NSC time-related proliferation; however, Nurr1 had no effect on proliferation. We also transplanted HBM-NSC into chicken embryos to examine their potential function in vivo. We found that transduction of HBM-NSC with rADV-Gli-1 or rADV-Shh and subsequent transplantation into chicken embryos increased HBM-NSC proliferation, whereas rADV-Nurr1 promoted migration and differentiation in vivo. Our findings suggest that HBM-NSC can be efficiently expanded and differentiated in vitro and in vivo by overexpressing Gli-1, Shh or Nurr1.

Visual hallucinations in posterior cortical atrophy

BACKGROUND

Visual hallucinations have been reported to occur in up to 25% of patients who meet the criteria for posterior cortical atrophy (PCA). It is not known, however, whether patients who meet the criteria for PCA and have hallucinations are different from those who meet the criteria and do not have hallucinations.

OBJECTIVE

To compare the clinical and imaging features of patients with PCA with and without well-formed visual hallucinations.

DESIGN

Case-control study.

SETTING

Tertiary care medical center.

PATIENTS

Fifty-nine patients fulfilling the criteria for PCA were retrospectively identified and divided into 2 groups based on the presence (n = 13) or absence (n = 46) of visual hallucinations.

MAIN OUTCOME MEASURES

Statistically significant clinical differences and imaging differences using voxel-based morphometry between the 2 groups.

RESULTS

In patients with PCA and hallucinations, parkinsonism and rapid eye movement sleep behavior disorder occurred more frequently, as did myoclonic jerks (P<.001 for both). Voxel-based morphometry showed greater atrophy in a network of structures, including the primary visual cortex, lentiform nuclei, thalamus, basal forebrain, and midbrain, in patients with hallucinations.

CONCLUSIONS

Hallucinations in patients with PCA are associated with parkinsonism, rapid eye movement sleep behavior disorder, and myoclonic jerks. The voxel-based morphometry results suggest that hallucinations in PCA cannot be exclusively attributed to atrophy of the posterior association cortices and may involve a circuit of thalamocortical connections.

Disturbance of rapid eye movement sleep in spinocerebellar ataxia type 2

Five genetically confirmed spinocerebellar ataxia type 2 (SCA2) patients were admitted to our sleep laboratory for two all-night video-polysomnographies. A standard montage was used, including electroencephalography, vertical and horizontal electrooculography, electromyography of mental, submental, and tibialis anterior muscles, and respiratory monitoring. Four of five SCA2 patients had insufficient muscle atonia during rapid eye movement (REM) sleep. All patients exhibited myoclonic jerks during REM sleep, while elaborated behavior was not observed in the video. Abnormal motor control during sleep with periodic leg movements and REM sleep without atonia occurs frequently in SCA2. This finding may reflect a dysfunction of dopaminergic and/or brainstem and cerebellar outflow pathways.

Sleep disturbances and excessive daytime sleepiness in Parkinson disease: an overview

Sleep disturbances are frequent in Parkinson disease. These disorders can be broadly categorized into those that involve nocturnal sleep and excessive daytime sleepiness. The disorders that are often observed during the night in PD include sleep fragmentation that may be due to recurrent PD symptoms, sleep apnea, Restless Leg Syndrome/ periodic limb movements and REM sleep behavior disorder. Excessive daytime sleepiness is also a common occurrence in PD. EDS can arise from several etiologies, and patients may have more than one etiology responsible. The causes of EDS include nocturnal sleep disorder with sleep deprivation and resulting daytime somnolence, the effect of drugs used to treat PD, and possibly neurodegeneration of central sleep/wake areas. Appropriate diagnosis of the sleep disturbance affecting a PD patient can lead to specific treatments that can consolidate nocturnal sleep and enhance daytime alertness.

Brainstem 1H-MR spectroscopy in patients with Parkinson's disease with REM sleep behavior disorder and IPD patients without dream enactment behavior

OBJECTIVES

The objective of our study was to evaluate brainstem involvement by 1H-MR spectroscopy (1H-MRS) method in patients with idiopathic Parkinson's disease (IPD) with REM sleep behavior disorder (RBD) and IPD without dream enactment behavior.

PATIENTS AND METHODS

We prospectively studied 12 IPD (3 females, 9 males) with a clinically and electrophysiologically confirmed RBD and 12 IPD (3 females, 9 males) patients without dream enactment behavior followed in Outpatient Clinics for Movement Disorders of Department of Neurology, Haseki Hospital. Using long and short TE single voxel 1H-MRS directed at ventral and dorsal pons, long TE NAA/Cr, Ch/Cr and short TE NAA/Cr, Ch/Cr, MI/Cr values of both groups were compared.

RESULTS

Although no difference was found between groups with RBD and IPD without dream enactment behavior in demographic characteristics, duration of disease, mean levodopa dosage and duration of levodopa use, all UPDRS scores (total, motor and cognitive) were worse in RBD group (p<0.05). There was no statistically significant difference in long TE NAA/Cr, Ch/Cr and short TE NAA/Cr, Ch/Cr, MI/Cr values obtained in both groups (p>0.05).

CONCLUSION

1H-MRS does not detect marked metabolic differences in the pons in subjects with IPD with RBD and IPD without dream enactment behavior. This finding suggests either that present methodologies are not sensitive to detect subtle metabolic changes in the pons of subjects with RBD or that the primary lesion of RBD exists in other REM sleep-related brain regions beyond the pons such as the substantia nigra, the basal ganglia or the limbic system.

Sleep disorders in Parkinson's disease

Depression, dementia, and physiologic changes contribute to the high prevalence of sleep disturbances in patients with Parkinson's disease (PD). Antiparkinsonian drugs also play a role in insomnia by increasing daytime sleepiness and affecting motor symptoms and depression. Common types of sleep disturbances in PD patients include nocturnal sleep disruption and excessive daytime sleepiness, restless legs syndrome, rapid eye movement sleep behavior disorder, sleep apnea, sleep walking and sleep talking, nightmares, sleep terrors, and panic attacks. A thorough assessment should include complete medical and psychiatric histories, sleep history, and a 1- to 2-week sleep diary or Epworth Sleepiness Scale evaluation. Polysomnography or actigraphy may also be indicated. Treatment should address underlying factors such as depression or anxiety. Hypnotic therapy for sleep disturbances in PD patients should be approached with care because of the risks of falling, agitation, drowsiness, and hypotension. Behavioral interventions may also be useful.