Restless legs syndrome, rapid eye movement sleep behavior disorder, and hypersomnia in patients with two parkin mutations: Sleep in Parkin Mutations

A neuron-glia lipid metabolic cycle couples daily sleep to mitochondrial homeostasis

Sleep is thought to be restorative to brain energy homeostasis, but it is not clear how this is achieved. We show here that Drosophila glia exhibit a daily cycle of glial mitochondrial oxidation and lipid accumulation that is dependent on prior wake and requires the Drosophila APOE orthologs NLaz and GLaz, which mediate neuron-glia lipid transfer. In turn, a full night of sleep is required for glial lipid clearance, mitochondrial oxidative recovery and maximal neuronal mitophagy. Knockdown of neuronal NLaz causes oxidative stress to accumulate in neurons, and the neuronal mitochondrial integrity protein, Drp1, is required for daily glial lipid accumulation. These data suggest that neurons avoid accumulation of oxidative mitochondrial damage during wake by using mitophagy and passing damage to glia in the form of lipids. We propose that a mitochondrial lipid metabolic cycle between neurons and glia reflects a fundamental function of sleep relevant for brain energy homeostasis.

The Genetic Landscape of Sleep Disorders in Parkinson's Disease

Parknson's disease (PD) is the second most common neurodegenerative disease, affecting 1% of people aged over 60. PD is characterized by a wide range of motor symptoms, however the clinical spectrum of PD covers a wide range of non-motor symptoms, as well. Sleep disorders are among the most common non-motor symptoms of PD, can occur at any stage of the disease and significantly affect quality of life. These include rapid eye movement sleep behavior disorder (RBD), restless legs syndrome (RLS), excessive daytime sleepiness (EDS), insomnia, obstructive sleep apnea (OSA) and circadian rhythm disturbances. One of the main challenges in PD research is identifying individuals during the prodromal phase of the disease. Combining genetic and prodromal data may aid the early identification of individuals susceptible to PD. This review highlights current data regarding the genetic component of sleep disorders in PD patients, focusing on genes that have currently been associated with this PD co-morbidity.

Rab11 rescues muscle degeneration and synaptic morphology in the park13/+ Parkinson model of Drosophila melanogaster

Mutation in parkin and pink1 is associated with Parkinson's disease (PD), the most common movement disorder characterized by muscular dysfunction. In a previous study, we observed that Rab11, a member of the small Ras GTPase family, regulates the mitophagy pathway mediated by Parkin and Pink1 in the larval brain of the Drosophila PD model. Here, we describe that the expression and interaction of Rab11 in the PD model of Drosophila is highly conserved across different phylogenic groups. The loss of function in these two proteins, i.e., Parkin and Pink1, leads to mitochondrial aggregation. Rab11 loss of function results in muscle degeneration, movement disorder and synaptic morphological defects. We report that overexpression of Rab11 in park13 heterozygous mutant improves muscle and synaptic organization by reducing mitochondrial aggregations and improving cytoskeleton structural organization. We also show the functional relationship between Rab11 and Brp, apre-synaptic scaffolding protein, required for synaptic neurotransmission. Using park13 heterozygous mutant and pink1RNAi lines, we showed reduced expression of Brp and consequently, there were synaptic dysfunctions including impaired synaptic transmission, decreased bouton size, increase in the bouton numbers, and the length of axonal innervations at the larval neuromuscular junction (NMJ). These synaptic alterations were rescued with the over-expression of Rab11 in the park13 heterozygous mutants. In conclusion, this work emphasizes the importance of Rab11 in rescuing muscle degeneration, movement dysfunction and synaptic morphology by preserving mitochondrial function in the PD model of Drosophila.

The Park Sleep subtype in Parkinson's disease: from concept to clinic

INTRODUCTION

The heterogeneity of Parkinson's disease (PD) is evident from descriptions of non-motor (NMS) subtypes and Park Sleep, originally identified by Sauerbier et al. 2016, is one such clinical subtype associated with the predominant clinical presentation of sleep dysfunctions including excessive daytime sleepiness (EDS), along with insomnia.

AREAS COVERED

A literature search was conducted using the PubMed, Medline, Embase, and Web of Science databases, accessed between 1 February 2023 and 28 March 2023. In this review, we describe the clinical subtype of Park Sleep and related 'tests' ranging from polysomnography to investigational neuromelanin MRI brain scans and some tissue-based biological markers.

EXPERT OPINION

Cholinergic, noradrenergic, and serotonergic systems are dominantly affected in PD. Park Sleep subtype is hypothesized to be associated primarily with serotonergic deficit, clinically manifesting as somnolence and narcoleptic events (sleep attacks), with or without rapid eye movement behavior disorder (RBD). In clinic, Park Sleep recognition may drive lifestyle changes (e.g. driving) along with therapy adjustments as Park Sleep patients may be sensitive to dopamine D3 active agonists, such as ropinirole and pramipexole. Specific dashboard scores based personalized management options need to be implemented and include pharmacological, non-pharmacological, and lifestyle linked advice.

Neurological Insights into Sleep Disorders in Parkinson's Disease

Parkinson's disease (PD) is a common multidimensional neurological disorder characterized by motor and non-motor features and is more prevalent in the elderly. Sleep disorders and cognitive disturbances are also significant characteristics of PD. Sleep is an important physiological process for normal human cognition and physical functioning. Sleep deprivation negatively impacts human physical, mental, and behavioral functions. Sleep disturbances include problems falling asleep, disturbances occurring during sleep, abnormal movements during sleep, insufficient sleep, and excessive sleep. The most recognizable and known sleep disorders, such as rapid-eye-movement behavior disorder (RBD), insomnia, excessive daytime sleepiness (EDS), restless legs syndrome (RLS), sleep-related breathing disorders (SRBDs), and circadian-rhythm-related sleep-wake disorders (CRSWDs), have been associated with PD. RBD and associated emotional disorders are common non-motor symptoms of PD. In individuals, sleep disorders and cognitive impairment are important prognostic factors for predicting progressing neurodegeneration and developing dementia conditions in PD. Studies have focused on RBD and its associated neurological changes and functional deficits in PD patients. Other risks, such as cognitive decline, anxiety, and depression, are related to RBD. Sleep-disorder diagnosis is challenging, especially in identifying the essential factors that disturb the sleep-wake cycle and the co-existence of other concomitant sleep issues, motor symptoms, and breathing disorders. Focusing on sleep patterns and their disturbances, including genetic and other neurochemical changes, helps us to better understand the central causes of sleep alterations and cognitive functions in PD patients. Relations between α-synuclein aggregation in the brain and gender differences in sleep disorders have been reported. The existing correlation between sleep disorders and levels of α-synuclein in the cerebrospinal fluid indicates the risk of progression of synucleinopathies. Multidirectional approaches are required to correlate sleep disorders and neuropsychiatric symptoms and diagnose sensitive biomarkers for neurodegeneration. The evaluation of sleep pattern disturbances and cognitive impairment may aid in the development of novel and effective treatments for PD.

Genetic heterogeneity on sleep disorders in Parkinson's disease: a systematic review and meta-analysis

A growing amount of evidence has indicated contributions of variants in causative genes of Parkinson’s disease (PD) to the development of sleep disturbance in PD and prodromal PD stages. In this article, we aimed to investigate the role of genetics in sleep disorders in PD patients and asymptomatic carriers at prodromal stage of PD. A systematic review and meta-analysis of observational studies was conducted based on the MEDLINE, EMBASE and PsychINFO databases. A pooled effect size was calculated by odds ratio (OR) and standard mean difference (SMD). Forty studies were selected for quantitative analysis, including 17 studies on glucocerebrosidase (GBA), 25 studies on Leucine-rich repeat kinase 2 (LRRK2) and 7 on parkin (PRKN) genes, and 3 studies on alpha-synuclein gene (SNCA) were used for qualitative analysis. Patients with PD carrying GBA variants had a significantly higher risk for rapid-eye-movement behavior disorders (RBD) (OR, 1.82) and higher RBD Screening Questionnaire scores (SMD, 0.33). Asymptomatic carriers of GBA variants had higher severity of RBD during follow-up. Patients with PD carrying the LRRK2 G2019S variant had lower risk and severity of RBD compared with those without LRRK2 G2019S. Variants of GBA, LRRK2 and PRKN did not increase or decrease the risk and severity of excessive daytime sleepiness and restless legs syndrome in PD. Our findings suggest that the genetic heterogeneity plays a role in the development of sleep disorders, mainly RBD, in PD and the prodromal stage of PD.

Na+ leak-current channel (NALCN) at the junction of motor and neuropsychiatric symptoms in Parkinson's disease

Parkinson's disease (PD) is a debilitating movement disorder often accompanied by neuropsychiatric symptoms that stem from the loss of dopaminergic function in the basal ganglia and altered neurotransmission more generally. Akinesia, postural instability, tremors and frozen gait constitute the major motor disturbances, whereas neuropsychiatric symptoms include altered circadian rhythms, disordered sleep, depression, psychosis and cognitive impairment. Evidence is emerging that the motor and neuropsychiatric symptoms may share etiologic factors. Calcium/ion channels (CACNA1C, NALCN), synaptic proteins (SYNJ1) and neuronal RNA-binding proteins (RBFOX1) are among the risk genes that are common to PD and various psychiatric disorders. The Na⁺ leak-current channel (NALCN) is the focus of this review because it has been implicated in dystonia, regulation of movement, cognitive impairment, sleep and circadian rhythms. It regulates the resting membrane potential in neurons, mediates pace-making activity, participates in synaptic vesicle recycling and is functionally co-localized to the endoplasmic reticulum (ER)-several of the major processes adversely affected in PD. Here, we summarize the literature on mechanisms and pathways that connect the motor and neuropsychiatric symptoms of PD with a focus on recurring relationships to the NALCN. It is hoped that the various connections outlined here will stimulate further discussion, suggest additional areas for exploration and ultimately inspire novel treatment strategies.

Quality of Life in Newly Diagnosed Patients With Parkin-Related Parkinson's Disease

Introduction: Mutations in the Parkin gene are the most common cause of autosomal recessive early-onset Parkinson's disease (PD). However, little is known about the quality of life (QoL) in Parkin-related PD. Here, we investigated the patterns of QoL in newly diagnosed Parkin-related PD patients.

Methods: Newly diagnosed PD patients (diagnosis made within 12 months) who had an age of onset (AOO) below 40 and underwent a PD-related genetic testing, were recruited (n = 148). Among them, 24 patients carried bi-allelic variants in Parkin (PD-Parkin) and 24 patients did not have any known causative PD mutations, or risk variants (GU-EOPD). The clinical materials, relevant factors and determinants of QoL were analyzed.

Results: PD-Parkin patients had a younger AOO (p = 0.003) and longer disease duration (p = 0.005). After adjustment for AOO and disease duration, more dystonia (p = 0.034), and worse scores of non-motor symptoms including Beck depression inventory (BDI, p = 0.035), Epworth sleepiness scale (ESS, p = 0.044), and subdomains of depression/anxiety (p = 0.015) and sleep disorders (p = 0.005) in Non-motor symptoms questionnaire, were found in PD-Parkin comparing with GU-EOPD. PD-Parkin patients had poorer QoL (adjusted p = 0.045), especially in the mobility (adjusted p = 0.025), emotional well-being (adjusted p = 0.015) and bodily discomfort dimensions (adjusted p = 0.016). BDI scores (p = 0.005) and ESS scores (p = 0.047) were significant determinants of QoL in PD-Parkin.

Conclusion: Newly diagnosed PD-Parkin patients showed worse QoL. More depression and excessive daytime sleepiness predicted worse QoL. For clinicians, management of depression and excessive daytime sleepiness is suggested to better improve QoL in patients with Parkin mutations.

Profiling Non-motor Symptoms in Monogenic Parkinson's Disease

Parkinson’s disease (PD) is the second most common neurodegenerative disease in the elder population, pathologically characterized by the progressive loss of dopaminergic neurons in the substantia nigra. While the precise mechanisms underlying the pathogenesis of PD remain unknown, various genetic factors have been proved to be associated with PD. To date, at least 23 loci and 19 disease-causing genes for PD have been identified. Although monogenic (often familial) cases account for less than 5% of all PD patients, exploring the phenotypes of monogenic PD can help us understand the disease pathogenesis and progression. Primary motor symptoms are important for PD diagnosis but only detectable at a relatively late stage. Despite typical motor symptoms, various non-motor symptoms (NMS) including sensory complaints, mental disorders, autonomic dysfunction, and sleep disturbances also have negative impacts on the quality of life in PD patients and pose major challenges for disease management. NMS is common in all stages of the PD course. NMS can occur long before the onset of PD motor symptoms or can present in the middle or late stage of the disease accompanied by motor symptoms. Therefore, the profiling and characterization of NMS in monogenic PD may help the diagnosis and differential diagnosis of PD, which thereby can execute early intervention to delay the disease progression. In this review, we summarize the characteristics, clinical phenotypes, especially the NMS of monogenic PD patients carrying mutations of SNCA, LRRK2, VPS35, Parkin, PINK1, DJ-1, and GBA. The clinical implications of this linkage between NMS and PD-related genes are also discussed.

Non-motor Symptoms in Parkinson's Disease Patients with Parkin Mutations: More Depression and Less Executive Dysfunction

The purpose of this study was to identify differences between genetically undefined (GU) early-onset Parkinson's disease (EOPD) patients and carriers of Parkin mutations on non-motor symptoms (NMSs). EOPD patients (N = 261) underwent targeted sequencing of Parkinson's disease (PD) related genes. Among them, 53 cases carried homozygous or compound heterozygous Parkin mutations (Parkin group) while 208 did not carry known causative PD mutations or risk factors of GBA or Parkin heterozygous mutations (GU group). NMSs were evaluated by face-to-face interviews, self-completed questionnaires and results on a neuropsychological battery. Linear regression and logistic regression models were applied to assess the predictors of NMSs. Parkin patients had younger ages of onset (AOO) (p < 0.001), longer disease durations (p < 0.001) and lower grades of Hoehn and Yarh (H&Y) (p = 0.007). Results on the neuropsychological battery showed a shorter time in Trail Making Test (TMT) (part B) in Parkin patients (p = 0.034) compared to GU patients. After adjusting for AOO, disease duration, H&Y, and levodopa equivalent daily dose (LEDD), there was a higher depression index on the Beck Depression Inventory (BDI) (p = 0.013) and better performance (p = 0.038) on executive function in the Parkin group compared to the GU group. No significant differences were found for autonomic functions, sleep-wake problems or other domains of cognitive function. Our study showed that the Parkin mutation status might be a good predictor of symptoms of depression without an impact on executive function. While these findings need to be confirmed in larger cohorts, they identify a need to screen for depression. Graphical Abstract Flow chart of genetic tests.

Restless Legs Syndrome and Parkinson Disease: A Causal Relationship Between the Two Disorders?

Restless Legs Syndrome/Willis-Ekbom Disease (RLS/WED) is a common sleep related movement disorder that can be idiopathic or occurs in comorbidity with other medical conditions such as polyneuropathy, iron deficiency anemia, multiple sclerosis, hypertension and cardiovascular diseases. In recent years, a growing body of literature investigated the association between RLS/WED and Parkinson's Disease (PD). Several questions regarding the comorbidity between these two disorders are still unanswered. If the insurgence of RLS/WED may precede the onset of PD, or if RLS/WED could represent a secondary condition of PD and if impaired dopaminergic pathway may represent a bridge between these two conditions are still debatable issues. In this review, we critically discuss the relationship between RLS/WED and PD by reviewing cross sectional and longitudinal studies, as well as the role of dopamine in these disorders. A twofold interpretation have to be taken into account: dopaminergic therapy may have a crucial role in the development of RLS/WED in PD patients or RLS/WED can be conceived as an early manifestation of PD rather than a risk factor. Several studies showed a high prevalence of RLS/WED in PD patients and several findings related to dopaminergic and iron alterations in both disorders, however up to now it is difficult to find a point of agreement between studies. A greater number of systematic and strongly controlled longitudinal studies as well as basic pathophysiological investigations particularly in RLS/WED are needed to clarify this complex relationship.

Investigation of non-motor symptoms in first-degree relatives of patients with Parkinson's disease

OBJECTIVE

Non-motor symptoms (NMS) are important prodromal characteristics of Parkinson's disease (PD). However, the incidence of NMS in first-degree relatives, such as siblings of PD patients, is still unknown.

METHODS

A total of 98 PD patients of the Affiliated Hospital of Yangzhou University were recruited; 210 siblings of these patients were included in a first-degree relatives (FDR) group and 250 healthy individuals were included in a control group. Various scales were used to assess NMS, including depression, anxiety, cognitive function, sleep status, constipation, daytime sleepiness, Rapid-Eye-Movement Sleep Behavior Disorder (RBD), and Restless Legs Syndrome (RLS).

RESULTS

NMS were more common in the PD group than the control group. The incidence of anxiety (OR = 3.434, 95%CI: 2.058-5.731, P < 0.001), depression (OR = 2.438, 95%CI: 1.289-4.609, P = 0.005), and RBD (OR = 4.120, 95%CI: 1.897-8.945, P < 0.001) was higher in the FDR group than the control group. There were non-significant differences in constipation, cognitive impairment, sleep disorder, daytime sleepiness, and RLS between the two groups. The incidence of RLS in FDR of PD with an age of onset <60 years was higher than in the controls (OR = 2.273, 95%CI: 1.107-4.667, P = 0.023).

CONCLUSIONS

Siblings of PD are more likely to suffer from anxiety, depression and RBD than the general population. RLS is more common in siblings of PD with onset age<60 than in the general population. It is speculated that PD patients and their siblings have common pathogenic genetic factors and early living environment for neurodegeneration.

Sleep disorders and Parkinson disease; lessons from genetics

Parkinson disease is a common, age-related neurodegenerative disorder, projected to afflict millions of individuals in the near future. Understanding its etiology and identifying clinical, genetic or biological markers for Parkinson disease onset and progression is therefore of major importance. Various sleep-related disorders are the most common group of non-motor symptoms in advanced Parkinson disease, but they can also occur during its prodromal phase. However, with the exception of REM sleep behavior disorder, it is unclear whether they are part of the early pathological process of Parkinson disease, or if they develop as Parkinson disease advances because of treatments and neurodegeneration progression. The advancements in genetic studies in the past two decades have generated a wealth of information, and recent genetic studies offer new insight on the association of sleep-related disorders with Parkinson disease. More specifically, comparing genetic data between Parkinson disease and sleep-related disorders can clarify their association, which may assist in determining whether they can serve as clinical markers for Parkinson disease risk or progression. In this review, we discuss the current knowledge on the genetics of sleep-related disorders in Parkinson disease context, and the potential implications on research, diagnosis, counseling and treatment.

Association of Restless Legs Syndrome With Incident Parkinson's Disease

Study Objectives

The association between restless legs syndrome (RLS) and Parkinson's disease (PD) has been extensively studied with inconclusive results; therefore, we prospectively examined the associations of the presence of RLS with development of incident PD.

Methods

From a nationally representative prospective cohort of almost 3.5 million US veterans (age: 60 ± 14 years, 93% male, median follow-up time of 7.8 years [interquartile range: 6.4-8.4 years]), we created a propensity-matched cohort of 100882 PD-free patients and examined the association between prevalent RLS and incident PD. This association was also assessed in the entire cohort. Associations were examined using Cox models.

Results

There were 68 incident PD events (0.13%, incidence rate 1.87 [1.48-2.37]/10000 patient-years) in the RLS-negative group, and 185 incident PD events (0.37%, incidence rate 4.72 [4.09-5.45]/10000 patient-years) in the RLS-positive group in the propensity-matched cohort. Prevalent RLS was associated with more than twofold higher risk of incident PD (hazard ratio [HR]: 2.57, 95% confidence interval [CI]: 1.95-3.39) compared to RLS-negative patients. Qualitatively similar results were found when we examined the entire 3.5 million cohort: Prevalent RLS was associated with more than twofold higher risk of incident PD (multivariable adjusted HR: 2.81, 95%CI: 2.41-3.27).

Conclusion

RLS and PD share common risk factors. In this large cohort of US veterans, we found that prevalent RLS is associated with higher risk of incident PD during 8 years of follow-up, suggesting that RLS could be an early clinical feature of incident PD.

Hypersomnia in Neurodegenerative Diseases

Hypersomnia is a common complaint in many patients with neurodegenerative diseases and a major cause of decreased quality of life. This article discusses the prevalence and factors associated with hypersomnia in patients with a variety of neurodegenerative diseases affecting the central nervous system, including tauopathies, synucleinopathies, and other conditions. Common nocturnal sleep problems that may result in daytime hypersomnia are delineated. A clinical approach to hypersomnia in patients with neurodegenerative diseases, recommended diagnostic testing, and available treatment options are also discussed.

Drosophila PINK1 and parkin loss-of-function mutants display a range of non-motor Parkinson's disease phenotypes

Parkinson's disease (PD) is more commonly associated with its motor symptoms and the related degeneration of dopamine (DA) neurons. However, it is becoming increasingly clear that PD patients also display a wide range of non-motor symptoms, including memory deficits and disruptions of their sleep-wake cycles. These have a large impact on their quality of life, and often precede the onset of motor symptoms, but their etiology is poorly understood. The fruit fly Drosophila has already been successfully used to model PD, and has been used extensively to study relevant non-motor behaviours in other contexts, but little attention has yet been paid to modelling non-motor symptoms of PD in this genetically tractable organism. We examined memory performance and circadian rhythms in flies with loss-of-function mutations in two PD genes: PINK1 and parkin. We found learning and memory abnormalities in both mutant genotypes, as well as a weakening of circadian rhythms that is underpinned by electrophysiological changes in clock neurons. Our study paves the way for further work that may help us understand the mechanisms underlying these neglected aspects of PD, thus identifying new targets for treatments to address these non-motor problems specifically and perhaps even to halt disease progression in its prodromal phase.

Genetics of Parkinson's Disease: Genotype-Phenotype Correlations

Since the first discovery of a specific genetic defect in the SNCA gene, encoding for α-synuclein, as a causative factor for Parkinson's disease 20 years ago, a multitude of other genes have been linked to this disease in rare cases with Mendelian inheritance. Furthermore, the genetic contribution to the much more common sporadic disease has been demonstrated through case control association studies and, more recently, genome-wide association studies. Interestingly, some of the genes with Mendelian inheritance, such as SNCA, are also relevant to the sporadic disease, suggesting common pathogenetic mechanisms. In this review, we place an emphasis on Mendelian forms, and in particular genetic defects which present predominantly with Parkinsonism. We provide details into the particular phenotypes associated with each genetic defect, with a particular emphasis on nonmotor symptoms. For genetic defects for whom a sufficient number of patients has been assessed, there are evident genotype-phenotype correlations. However, it should be noted that patients with the same causative mutation may present with distinctly divergent phenotypes. This phenotypic variability may be due to genetic, epigenetic or environmental factors. From a clinical and genetic point of view, it will be especially interesting in the future to identify genetic factors that modify disease penetrance, the age of onset or other specific phenotypic features.

Sleep aspects on video-polysomnography in LRRK2 mutation carriers

BACKGROUND

Rapid eye movement sleep behavior disorder and sleepiness precede or accompany idiopathic Parkinson's disease (PD), but their presence in subjects with leucine-rich repeat kinase 2 mutations is unknown.

METHODS

Ten patients with leucine-rich repeat kinase 2-associated PD, four healthy leucine-rich repeat kinase 2 mutation carriers, 20 patients with idiopathic PD, and 12 healthy controls underwent clinical assessments and a nighttime video-polysomnography.

RESULTS

No sleep changes, no rapid eye movement sleep behavior disorder, or rapid eye movement sleep without atonia was found in the 14 subjects with leucine-rich repeat kinase 2mutations compared with controls, whereas 41% of patients with idiopathic PD had rapid eye movement sleep behavior disorder. Eventually, 20% of patients with leucine-rich repeat kinase 2-associated PD had abnormal periodic leg movements, a frequency similar to the idiopathic PD group frequency.

CONCLUSIONS

The sleep phenotype in leucine-rich repeat kinase 2 mutations parallels that of idiopathic PD, except for absent rapid eye movement sleep behavior disorder here in the presymptomatic and symptomatic stages.

Quality of sleep in young onset Parkinson's disease: Any difference from older onset Parkinson's disease

BACKGROUND

Sleep disorders occur commonly in Parkinson's disease and are often under-recognized and under treated in clinical practice.

OBJECTIVES

To determine the quality of sleep in patients with Young onset Parkinson's disease (YOPD) and to note whether there is any difference in quality of sleep from those patients with older onset Parkinson's disease (OOPD).

METHODS

One hundred and fifty six patients with Parkinson's disease (YOPD-51, OOPD-105) were clinically examined and quality of sleep was determined using Pittsburgh sleep quality index (PSQI), Parkinson's disease Sleep Scale (PDSS) and Epworth Sleep Scale (ESS). Other scales included Unified Parkinson's Disease Rating Scale -part III (UPDRS-III), Hoehn & Yahr Stage, Mini Mental Status Examination, Hamilton anxiety rating scale and Hamilton depression rating scale.

RESULTS

The frequency of insomnia was higher in OOPD (55.2%) as compared to YOPD (27.5%) group (p = 0.001). The frequency of nightmares was lower in YOPD (7.8%) when compared to OOPD (24.8%) group (p = 0.012). The mean hours of actual sleep per night were higher in YOPD patients. Global PSQI score was better in YOPD indicating good overall sleep quality in YOPD patients. The total ESS score was significantly lower in YOPD (p = 0.019). The total PDSS score was significantly better in YOPD patients (p = 0.018).

CONCLUSIONS

Patients with YOPD had an overall better quality of sleep with lesser incidence of insomnia, nightmares, daytime sleepiness and restlessness during sleep.

Circadian dysfunction may be a key component of the non-motor symptoms of Parkinson's disease: insights from a transgenic mouse model

Sleep disorders are nearly ubiquitous among patients with Parkinson's disease (PD), and they manifest early in the disease process. While there are a number of possible mechanisms underlying these sleep disturbances, a primary dysfunction of the circadian system should be considered as a contributing factor. Our laboratory's behavioral phenotyping of a well-validated transgenic mouse model of PD reveals that the electrical activity of neurons within the master pacemaker of the circadian system, the suprachiasmatic nuclei (SCN), is already disrupted at the onset of motor symptoms, although the core features of the intrinsic molecular oscillations in the SCN remain functional. Our observations suggest that the fundamental circadian deficit in these mice lies in the signaling output from the SCN, which may be caused by known mechanisms in PD etiology: oxidative stress and mitochondrial disruption. Disruption of the circadian system is expected to have pervasive effects throughout the body and may itself lead to neurological and cardiovascular disorders. In fact, there is much overlap in the non-motor symptoms experienced by PD patients and in the consequences of circadian disruption. This raises the possibility that the sleep and circadian dysfunction experienced by PD patients may not merely be a subsidiary of the motor symptoms, but an integral part of the disease. Furthermore, we speculate that circadian dysfunction can even accelerate the pathology underlying PD. If these hypotheses are correct, more aggressive treatment of the circadian misalignment and sleep disruptions in PD patients early in the pathogenesis of the disease may be powerful positive modulators of disease progression and patient quality of life.

Linking restless legs syndrome with Parkinson's disease: clinical, imaging and genetic evidence

Restless legs syndrome (RLS) and Parkinson's disease (PD) are both common neurological disorders. There has been much debate over whether an etiological link between these two diseases exists and whether they share a common pathophysiology. Evidence pointing towards a link includes response to dopaminergic agents in PD and RLS, suggestive of underlying dopamine dysfunction in both conditions. The extrastriatal dopaminergic system, in particular altered spinal dopaminergic modulation, may be variably involved in PD patients with RLS symptoms. In addition, there is now evidence that the nigrostriatal system, primarily involved in PD, is also affected in RLS. Furthermore, an association of RLS with the parkin mutation has been suggested. The prevalence of RLS has also been reported to be increased in other disorders of dopamine regulation. However, clinical association studies and functional imaging have produced mixed findings. Conflicting accounts of emergence of RLS and improvement in RLS symptoms after deep brain stimulation (DBS) also contribute to the uncertainty surrounding the issue. Among the strongest arguments against a common pathophysiology is the role of iron in RLS and PD. While elevated iron levels in the substantia nigra contribute to oxidative stress in PD, RLS is a disorder of relative iron deficiency, with symptoms responding to replacement therapy. Recent ultrasonography studies have suggested that, despite overlapping clinical features, the mechanisms underlying idiopathic RLS and RLS associated with PD may differ. In this review, we provide a concise summary of the clinical, imaging and genetic evidence exploring the link between RLS and PD.

Diagnostic tools for REM sleep behavior disorder

BACKGROUND

Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia characterized by loss of muscle atonia during REM sleep that results in motor behaviors. Diagnosis of RBD involves a clinical interview in which history of dream enactment behaviors is elicited and a subsequent overnight polysomnography (PSG) evaluation to assess for REM sleep without atonia (RWA) and/or observe motor behaviors during REM sleep. Therefore, the nature of RBD diagnosis involves both subjective and objective measurements that attempt to qualify and quantify the different diagnostic sub-criteria.

OBJECTIVES

The primary aim of the current study was to identify and summarize the available clinical measurements that have been used for RBD assessment.

METHODS

Two major online databases (MEDLINE and PsycInfo) were searched for articles developing, validating, or evaluating psychometric properties of the RBD diagnostic criteria or methods used for diagnosis. Studies of adult subjects (18 years or more) that included sufficient psychometric data for validation were included.

RESULTS

Fifty-eight studies were found to meet review criteria. The objective measurements for assessment of RBD reviewed included visual electromyographic (EMG) scoring methods, computerized EMG scoring methods, cardiac (123)I-metaiodobenzylguanidine ((123)I-MIBG) scintigraphy, actigraphy, behavioral classification and video analysis. Subjective measurements of RBD included interviews and questionnaires.

CONCLUSION

Sleep history may be sufficient for diagnosis of RBD in some populations. However, PSG is necessary for a definitive diagnosis. EMG scoring methods vary in definition used and there is no single accepted approach to scoring muscle activity. Additional validation studies are required for establishing cutoff scores for the different methods. Questionnaires were shown to be appropriate screening tools, yet further validation in different populations is necessary.

[REM sleep behavior disorder: an overt access to motor and cognitive control during sleep]

Rapid eye movement (REM) sleep behavior disorder (RBD) is characterized by violent, or potentially violent, movements during REM sleep, corresponding to enacted dreams. During sleep monitoring, there is a partial or total loss of the normal muscle atonia during REM sleep. REM sleep behavior disorder predominantly affects elderly subjects without any other disease (idiopathic RBD, a precursor of Parkinson disease and Lewy body dementia) or suffering from various neurological and neurodegenerative diseases, mainly synucleinopathies. In addition to being a treatable cause of nocturnal injury of the patients or their bed-partners, RBD is a fantastic window into motor and cognitive control during REM sleep. Notably, parkinsonism transiently disappears during RBD. The patient's voice is louder and better articulated than when awake, and movements are rapid (but jerky) suggesting that the deleterious message from the basal ganglia to the primary motor cortex is reduced or bypassed. As we observed culturally-acquired behaviors, retired patients practicing their former work with mastered gestures, as well as sentences pronounced with appropriate prosody, gesturing, fluency, and syntax during the RBD, we suggest that these behaviors are generated by the same cortical areas as during wakefulness. This model also enables the demonstration that REM during REM sleep are coded in the same direction as the arm and hand movements, as if the dreamer were scanning the dream images. This online access to the motor and verbal dream scenario (through the video and audio monitoring), and the physiological measures (via the EEG, eye movements, muscle tone, respiration, heart rate), together with the offline access to the mental content (dream report after the awakening) constitute a triangulation for validating new hypotheses about REM sleep and dreams.

Genetic etiology of Parkinson disease associated with mutations in the SNCA, PARK2, PINK1, PARK7, and LRRK2 genes: a mutation update

To date, molecular genetic analyses have identified over 500 distinct DNA variants in five disease genes associated with familial Parkinson disease; alpha-synuclein (SNCA), parkin (PARK2), PTEN-induced putative kinase 1 (PINK1), DJ-1 (PARK7), and Leucine-rich repeat kinase 2 (LRRK2). These genetic variants include approximately 82% simple mutations and approximately 18% copy number variations. Some mutation subtypes are likely underestimated because only few studies reported extensive mutation analyses of all five genes, by both exonic sequencing and dosage analyses. Here we present an update of all mutations published to date in the literature, systematically organized in a novel mutation database (http://www.molgen.ua.ac.be/PDmutDB). In addition, we address the biological relevance of putative pathogenic mutations. This review emphasizes the need for comprehensive genetic screening of Parkinson patients followed by an insightful study of the functional relevance of observed genetic variants. Moreover, while capturing existing data from the literature it became apparent that several of the five Parkinson genes were also contributing to the genetic etiology of other Lewy Body Diseases and Parkinson-plus syndromes, indicating that mutation screening is recommendable in these patient groups.