REM sleep behavior disorder (RBD)

Since its first description in 1986 by Dr. Carlos Schenck, and his group's subsequent report of the delayed emergence of a Parkinsonian disorder in idiopathic RBD patients one decade later, RBD has emerged in recent years as one of the most promising markers of prodromal Parkinson's (References 2, 3). RBD is present in 25-58% of patients with Parkinson's disease and up to 90% of those with Dementia with Lewy Bodies (DLB) or Multiple System Atrophy (MSA). In a substantial proportion of these patients RBD onset occurs before motor symptoms. Critically, when seen in isolation, RBD is a highly specific marker of future synucleinopathy: long-term cohort studies indicate that more than 80% of people who develop isolated RBD will go on to develop an alpha-synuclein related neurodegenerative disorder. Recently, the largest ever study of 1280 polysomnographically-diagnosed RBD subjects from 24 International RBD Study Group sleep centres by a single author group, found an overall conversion rate from iRBD to an overt neurodegenerative syndrome of 6.3% per year. RBD is therefore common, representative of a large proportion of sporadic disease, and provides a unique window for the study of prodromal neurodegeneration, whether it be Parkinson's or Dementia.

Application of a Simple Parkinson's Disease Risk Score in a Longitudinal Population-Based Cohort

BACKGROUND

Identifying individuals at risk of developing Parkinson's disease (PD) is critical to define target populations for future neuroprotective trials.

OBJECTIVE

The objective of this study was to apply the PREDICT-PD algorithm of risk indicators for PD in a prospective community-based study (the Bruneck study), representative of the general elderly population.

METHODS

PREDICT-PD risk scores were calculated based on risk factor assessments obtained at baseline (2005, n = 574 participants). Cases of incident PD were identified at 5-year and 10-year follow-ups. Participants with PD or secondary parkinsonism at baseline were excluded (n = 35). We analyzed the association of log-transformed risk scores with the presence of well-established markers as surrogates for PD risk at baseline and with incident PD at follow-up.

RESULTS

A total of 20 participants with incident PD were identified during follow-up (11 after 5 years and 9 after 10 years). Baseline PREDICT-PD risk scores were associated with incident PD with odds ratios of 2.09 (95% confidence interval, 1.35-3.25; P = 0.001) after 5 years and of 1.95 (1.36-2.79; P < 0.001) after 10 years of follow-up per doubling of risk scores. In addition, higher PREDICT-PD scores were significantly correlated with established PD risk markers (olfactory dysfunction, signs of rapid eye movement sleep behavior disorder and motor deficits) and significantly associated with higher probability for prodromal PD according to the Movement Disorder Society research criteria at baseline.

CONCLUSIONS

The PREDICT-PD score was associated with an increased risk for incident PD in our sample and may represent a useful first screening step in future algorithms aiming to identify cases of prodromal PD. © 2020 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Cohort profile: the Oxford Parkinson's Disease Centre Discovery Cohort MRI substudy (OPDC-MRI)

PURPOSE

The Oxford Parkinson's Disease Centre (OPDC) Discovery Cohort MRI substudy (OPDC-MRI) collects high-quality multimodal brain MRI together with deep longitudinal clinical phenotyping in patients with Parkinson's, at-risk individuals and healthy elderly participants. The primary aim is to detect pathological changes in brain structure and function, and develop, together with the clinical data, biomarkers to stratify, predict and chart progression in early-stage Parkinson's and at-risk individuals.

PARTICIPANTS

Participants are recruited from the OPDC Discovery Cohort, a prospective, longitudinal study. Baseline MRI data are currently available for 290 participants: 119 patients with early idiopathic Parkinson's, 15 Parkinson's patients with pathogenic mutations of the leucine-rich repeat kinase 2 or glucocerebrosidase (GBA) genes, 68 healthy controls and 87 individuals at risk of Parkinson's (asymptomatic carriers of GBA mutation and patients with idiopathic rapid eye movement sleep behaviour disorder-RBD).

FINDINGS TO DATE

Differences in brain structure in early Parkinson's were found to be subtle, with small changes in the shape of the globus pallidus and evidence of alterations in microstructural integrity in the prefrontal cortex that correlated with performance on executive function tests. Brain function, as assayed with resting fMRI yielded more substantial differences, with basal ganglia connectivity reduced in early Parkinson'sand RBD. Imaging of the substantia nigra with the more recent adoption of sequences sensitive to iron and neuromelanin content shows promising results in identifying early signs of Parkinsonian disease.

FUTURE PLANS

Ongoing studies include the integration of multimodal MRI measures to improve discrimination power. Follow-up clinical data are now accumulating and will allow us to correlate baseline imaging measures to clinical disease progression. Follow-up MRI scanning started in 2015 and is currently ongoing, providing the opportunity for future longitudinal imaging analyses with parallel clinical phenotyping.

Predictors of cognitive impairment in Parkinson's disease: a systematic review and meta-analysis of prospective cohort studies

INTRODUCTION

Cognitive impairment is a debilitating manifestation in Parkinson's disease (PD). We sought to investigate predictors of PD-CI (PD with cognitive impairment).

METHODS

We systematically searched PubMed and Cochrane Library for prospective cohort studies and pooled estimates via random-effects models. Primary analyses for all types of cognitive impairments and subgroup analyses by separate outcomes were conducted.

RESULTS

A total of 28,009 studies were identified, of which 57 studies with 31 factors were included in the meta-analysis. In the primary analysis, 13 factors were associated with PD-CI, comprising advanced age [relative risk (RR) = 1.07, 95% confidence interval (CI) = 1.03-1.12], age at onset (RR = 4.43, 95% CI = 1.87-10.54), postural-instability-gait disorder (RR = 3.76, 95% CI = 1.36-10.40), higher Hoehn and Yahr stage (RR = 1.83, 95% CI = 1.35-2.47), higher UPDRS III score (RR = 1.04, 95% CI = 1.01-1.08), rapid eye movement sleep behavior disorder (RR = 3.72, 95% CI = 1.20-11.54), hallucinations (RR = 3.09, 95% CI = 1.61-5.93), orthostatic hypotension (RR = 2.98, 95% CI = 1.41-6.28), anxiety (RR = 2.59, 95% CI = 1.18-5.68), APOE ε2 (RR = 6.47, 95% CI = 1.29-32.53), APOE ε4 (RR = 3.04, 95% CI = 1.88-4.91), electroencephalogram theta power > median (RR = 2.93, 95% CI = 1.61-5.33), and alpha power < median (RR = 1.77, 95% CI = 1.07-2.92). In the subgroup analysis, MAPT H1/H1 genotype increased the risk of dementia in PD. Sixty-four studies were included in the systematic review, of which 12 factors were additionally correlated with PD-CI using single studies.

CONCLUSIONS

Advanced age, genetic variation in APOE and MAPT, gait disturbance, motor assessments, non-motor symptoms, and electroencephalogram may be promising predictors for PD-CI.

Sleep disorders in Wilson disease: a systematic review and meta-analysis

STUDY OBJECTIVES

Wilson disease (WD) is an autosomal recessive inherited disorder of copper metabolism resulting in pathologic accumulation of copper in many organs and tissues. Sleep disorders are highly prevalent in patients with WD. However, both prevalence rates and severity of different sleep disorders in patients with WD vary widely. The aims of the current study were to systematically review and perform a meta-analysis of the association between WD and prevalent sleep disorders, including insomnia, rapid eye movement (REM) sleep behavior disorder (RBD), excessive daytime sleepiness (EDS), sleep-disordered breathing (SDB), restless legs syndrome (RLS), periodic limb movement in sleep (PLM), cataplexy-like episodes (CLEs) and sleep paralysis, and objective sleep characteristics.

METHODS

We performed a systematic search of PubMed, EMBase, the Cochrane Library, PsycINFO and ISI Web of Science for case-control studies. A total of 7 studies with 501 participants were included.

RESULTS

We found that 54.1% of patients with WD experience sleep disorders and up to 7.65-fold higher odds compared to control patients. Specifically, patients with WD had higher rates of RBD, insomnia, and EDS based on self-reported questionnaires. No differences were observed in terms of RLS, PLM, or SDB between patients with WD and control patients. Furthermore, objective sleep disruptions based on polysomnographic studies included prolonged sleep onset latency and REM sleep onset latency, reduced total sleep time and sleep efficiency, higher percentage of stage N1 sleep and lower percentage of stage N2 sleep were observed in patients with WD.

CONCLUSIONS

Our study indicates that sleep disorders are frequent in patients with WD. Future studies should examine the longitudinal association of WD with sleep disturbances.

[Sleep disorders in Parkinson's disease]

Sleep disorder are common non-motor symptoms in Parkinson`s disease (PD). They can be found in different sleep stages or appear during the daytime. They correlate with faster progression of motor problems and lower quality of a patient's life. Sleep physiology, different sleep dysfunction such as: RBD-REM sleep behavior disorder, EDS - excessive daytime sleepiness, insomnia, OSAS-obstructive sleep apnea syndrome, and their clinical manifestation have been presented in this review. Diagnostic and therapy possibilities have been summarized as well. Particular attention has also been paid to the coexistence of various non-motor symptoms such as pain, depression or nocturia, and their correlations with sleeping problems.

Sleep and its disturbances in neurology

Sleep disturbances are important symptoms of neurological diseases and some so-called primary sleep disorders have a neurological nature. The development of medicine, the availability of sleep investigations and progress in the treatment of sleep disorders have caused that the care of neurological illness includes sleep-related problems. In addition, sleep disorders can be risk factors for neurological diseases (for example obstructive sleep apnea for stroke) or their prodromal stage (REM sleep behavior disorder is one of the first symptoms of synucleinopathies). The article gives a very brief overview of sleep disorders in relation to neurological diseases and vice versa.

Sleep in Parkinson's Disease with Impulse Control Disorder

PURPOSE OF REVIEW

This paper aims to explore the relationship between impulse-control disorders (ICDs) and sleep problems in patients with Parkinson's disease (PD) among scientific literature.

RECENT FINDINGS

Previously published results are controversial and sometimes inconclusive. ICDs and sleep disruption represent important non-motor features of Parkinson's disease, responsible for reducing quality of life and increasing burden of disease. The relationship between sleep problems and ICDs is complex and bidirectional. Indeed, sleep disturbances and fragmentation may play a crucial role in increasing susceptibility to impulsive behavior and may represent a risk factor for developing ICDs in PD patients. Moreover, REM sleep behavior disorder (RBD) and restless legs syndrome (RLS) have been indicated as independent risk factors for ICDs in PD patients. On the other hand, also ICDs may lead to sleep restriction and fragmentation, suggesting a bidirectional relationship. The association between sleep problems and ICDs in PD is far from being completely understood. Further studies are needed to confirm the nature of this relationship and its pathophysiology.

REM Sleep Behavior Disorder

Rapid eye movement sleep behavior disorder (RBD) is a brain disorder, characterized by the dream enactment during rapid eye movement (REM) sleep due to a lack of physiologic muscle atonia and increased muscle twitching. Schenk was the first to describe this disorder in 1986; however, few authors reported in the 1970-1980s loss of physiological muscle atonia combined with dream enactment in the course of brainstem disorders and as a consequence of alcoholism and antidepressant treatment. RBD affects less than 1% of the adult population, but can be found in up to 25-50% of neurodegenerative disorders including Parkinson's disease, multisystem atrophy, and dementia with Lewy body. In the last decade, many studies provided evidence that RBD precedes parkinsonian motor signs by several years, suggesting that RBD should no longer be considered a complication but a part of the prodromal phase of these diseases. Etiologically, primary (idiopathic RBD) and several secondary forms in addition to neurodegeneration (related to focal brainstem damage, narcolepsy, autoimmune disorders, and drugs) are known. Pathophysiologically, brainstem and supratentorial mechanisms involving glutamatergic, glycinergic, and GABA-ergic neurotransmission have been implicated. Recently, an animal model of RBD has been described. Clinical features consist of characteristic nocturnal behaviors, but also daytime symptoms including excessive sleepiness and cognitive alterations. The diagnosis of RBD is made according to international diagnostic criteria, based on medical history, and video-polysomnographic features. Current treatment strategies include actions which ensure a safe sleep environment, the avoidance of triggering/exacerbating factors and if necessary pharmacological (mainly clonazepam and melatonin) and non-pharmacological (e.g., behavioral measures) interventions. Future research should clarify the exact sleep-wake characteristics of RBD (also beyond REM sleep) and their evolution over time, the contribution of brainstem but also supratentorial mechanisms to its pathophysiology, and the (early?) diagnostic and (causative?) treatment consequences of RBD in the context of neurodegeneration.

Sleep and Parkinson Disease

Sleep disorders are prevalent in Parkinson disease (PD), a disease with well recognized motor dysfunction. Sleep related problems received little attention until the last three decades. Sleep disorders seen in PD patients include insomnia, excessive sleepiness, restless legs syndrome, REM sleep behavior disorder. Some of these can have significant impact and lower the quality of life in these patients. An understanding of sleep issues in PD can help identify them early and result in optimal management.

EEG recordings as a source for the detection of IRBD

The purpose of this pilot study was to develop a supportive algorithm for the detection of idiopathic Rapid Eye-Movement (REM) sleep Behaviour Disorder (iRBD) from EEG recordings. iRBD is defined as REM sleep without atonia with no current sign of neurodegenerative disease, and is one of the earliest known biomarkers of Parkinson's Disease (PD). It is currently diagnosed by polysomnography (PSG), primarily based on EMG recordings during REM sleep. The algorithm was developed using data collected from 42 control subjects and 34 iRBD subjects. A feature was developed to represent high amplitude contents of the EEG and a semi-automatic signal reduction method was introduced. The reduced feature set was used for a subject-based classification. With a subject specific re-scaling of the feature set and the use of an outlier detection classifier the algorithm reached an accuracy of 0.78. The result shows that EEG recordings contain valid information for a supportive algorithm for the detection of iRBD. Further investigation could lead to promising application of EEG recordings as a supportive source for the detection of iRBD.

[Parkinson Disease With Rapid Eye Movement Sleep Behavior Disorder]

Rapid eye movement (REM) sleep behavior disorder (RBD) is characterized by lack of muscle atonia during REM sleep and enactment of dream content. RBD is associated with Parkinson disease (PD) and has high incidence in PD patients. PD patient with RBD mainly presents rigid type, has longer disease duration, more severe motor and non-motor symptoms and poorer activity of daily living and life quality. The pathophysiological mechanisms of RBD may be related to dysfunctions of pontine tegmentum, locus coeruleus/sub-locus coeruleus complex and related projections. The diagnosis of RBD depends on clinical histories and video-polysomnography (v-PSG). Besides treatment for PD, protective measures have to be taken for patients and their sleep partners. If abnormal behaviors during sleep cause distress and danger,patients should be given drug therapy.

Altered sleep regulation in leptin-deficient mice

Recent epidemiological, clinical, and experimental studies have demonstrated important links between sleep duration and architecture, circadian rhythms, and metabolism, although the genetic pathways that interconnect these processes are not well understood. Leptin is a circulating hormone and major adiposity signal involved in long-term energy homeostasis. In this study, we tested the hypothesis that leptin deficiency leads to impairments in sleep-wake regulation. Male ob/ob mice, a genetic model of leptin deficiency, had significantly disrupted sleep architecture with an elevated number of arousals from sleep [wild-type (WT) mice, 108.2 ± 7.2 vs. ob/ob mice, 148.4 ± 4.5, P < 0.001] and increased stage shifts (WT, 519.1 ± 25.2 vs. ob/ob, 748.0 ± 38.8, P < 0.001) compared with WT mice. Ob/ob mice also had more frequent, but shorter-lasting sleep bouts compared with WT mice, indicating impaired sleep consolidation. Interestingly, ob/ob mice showed changes in sleep time, with increased amounts of 24-h non-rapid eye movement (NREM) sleep (WT, 601.5 ± 10.8 vs. ob/ob, 669.2 ± 13.4 min, P < 0.001). Ob/ob mice had overall lower body temperature (WT, 35.1 ± 0.2 vs. ob/ob, 33.4 ± 0.2°C, P < 0.001) and locomotor activity counts (WT, 25125 ± 2137 vs. ob/ob, 5219 ± 1759, P < 0.001). Ob/ob mice displayed an attenuated diurnal rhythm of sleep-wake stages, NREM delta power, and locomotor activity. Following sleep deprivation, ob/ob mice had smaller amounts of NREM and REM recovery sleep, both in terms of the magnitude and the duration of the recovery response. In combination, these results indicate that leptin deficiency disrupts the regulation of sleep architecture and diurnal rhythmicity.

Sleep and wakefulness disturbances in Parkinson's disease

Patients with Parkinson's disease experience prominent difficulties in maintaining sleep, painful night-time abnormal movements, and daytime sleepiness, sometimes culminating in sleep attacks. Recent insights into the pathophysiology of sleep disorders in PD points to a complex interaction between movement disorders, side-effects of dopamine agents and lesions in sleep-wake regulating systems. Treatment with dopamine agonists provides a twice higher risk of daytime sudden sleep episodes than levodopa, with no difference between ergotic and non ergotic compounds. Insomnia can be improved by a better control of night-time disability, restless legs syndrome and dystonia using subthalamic nucleus stimulation or night-time levodopa. A specific REM sleep disorder contributes to REM sleep behavior disorder and also to hallucinations (suggesting they could be awake dreams) and excessive daytime sleepiness. The management of sleep and alertness problems requires to analyze their potential causes, to monitor night-time and daytime sleep, and to subtly adjust psychotropic and dopaminergic treatment.