Clinical prediction of Parkinson's disease: planning for the age of neuroprotection

Educational Resources to Support Patients with Parasomnias

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

Plasma neurofilament light levels show elevation two years prior to diagnosis of amyotrophic lateral sclerosis in the UK Biobank

OBJECTIVE

Amyotrophic lateral sclerosis (ALS) is a debilitating neurodegenerative disease with profound unmet need. In patients carrying genetic mutations, elevations in neurofilament light (NfL) have been shown to precede symptom onset, however, the natural history of NfL in general ALS patients is less characterized.

METHODS

We performed a secondary analysis of the UK Biobank Pharma Proteomics Project (UKB-PPP), a subset of the UK Biobank, a population-based cohort study in the United Kingdom, to examine plasma NfL levels in 237 participants subsequently diagnosed with ALS. We applied logistic and Cox proportional hazards regression to compare cases to 42,752 population-based and 948 age and sex-matched controls. Genetic information was obtained from exome and genotype array data.Results and Conclusions: We observed that NfL was 1.42-fold higher in cases vs population-based controls. At two to three years pre-diagnosis, NfL levels in patients exceeded the 95th percentile of age and sex-matched controls. A time-to-diagnosis analysis showed that a 2-fold increase in NfL levels was associated with a 3.4-fold risk of diagnosis per year, with NfL being most predictive of case status at two years (AUC = 0.96). Participants with genetic variation that might put them at risk for familial disease (N = 46) did not show a different pattern of association than those without (N = 191).

DISCUSSION

Our findings show that NfL is elevated and discriminative of future ALS diagnosis up to two years prior to diagnosis in patients with and without genetic risk variants.

The Therapeutic Potential of Salidroside for Parkinson's Disease

Parkinson's disease (PD), a neurological disorder, is characterized by the progressive loss of dopaminergic (DA) neurons in the substantia nigra. Its incidence increases with age. Salidroside, a phenolic compound extracted from Sedum roseum, reportedly has multiple biological and pharmacological activities in the nervous system. However, its effects on PD remain unclear. In this review, we summarize the effects of salidroside on PD with regard to DA metabolism, neuronal protection, and glial activation. In addition, we summarize the susceptibility genes and their underlying mechanisms related to antioxidation, inflammation, and autophagy by regulating mitochondrial function, ubiquitin, and multiple signaling pathways involving NF-κB, mTOR, and PI3K/Akt. Although recent studies were based on animal and cellular experiments, this review provides evidence for further clinical utilization of salidroside for PD.

Serum MicroRNAs Predict Isolated Rapid Eye Movement Sleep Behavior Disorder and Lewy Body Diseases

BACKGROUND

Isolated rapid eye movement sleep behavior disorder (IRBD) is a well-established clinical risk factor for Lewy body diseases (LBDs), such as Parkinson's disease (PD) and dementia with Lewy bodies (DLB).

OBJECTIVE

To elucidate whether serum microRNA (miRNA) deregulation in IRBD can antedate the diagnosis of LBD by performing a longitudinal study in different progression stages of IRBD before and after LBD diagnosis and assessing the predictive performance of differentially expressed miRNAs by machine learning-based modeling.

METHODS

Using genome-wide miRNA analysis and real-time quantitative polymerase chain reaction validation, we assessed serum miRNA profiles from patients with IRBD stratified by dopamine transporter (DaT) single-photon emission computed tomography into DaT-negative IRBD (n = 17) and DaT-positive IRBD (n = 21), IRBD phenoconverted into LBD (n = 13), and controls (n = 20). Longitudinally, we followed up the IRBD cohort by studying three time point serum samples over 26 months.

RESULTS

We found sustained cross-sectional and longitudinal deregulation of 12 miRNAs across the RBD continuum, including DaT-negative IRBD, DaT-positive IRBD, and LBD phenoconverted IRBD (let-7c-5p, miR-19b-3p, miR-140, miR-22-3p, miR-221-3p, miR-24-3p, miR-25-3p, miR-29c-3p, miR-361-5p, miR-425-5p, miR-4505, and miR-451a) (false discovery rate P < 0.05). Age- and sex-adjusted predictive modeling based on the 12 differentially expressed miRNA biosignatures discriminated IRBD and PD or DLB from controls with an area under the curve of 98% (95% confidence interval: 89-99%).

CONCLUSIONS

Besides clinical diagnosis of IRBD or imaging markers such as DaT single-photon emission computed tomography, specific miRNA biosignatures alone hold promise as progression biomarkers for patients with IRBD for predicting PD and DLB clinical outcomes. Further miRNA studies in other PD at-risk populations, such as LRRK2 mutation asymptomatic carriers or hyposmic subjects, are warranted. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Antibiotic Consumption Patterns in European Countries Are Associated with the Prevalence of Parkinson’s Disease; the Possible Augmenting Role of the Narrow-Spectrum Penicillin

Parkinson’s disease: Parkinson’s disease (PD) is the second-most common neurodegenerative disease, affecting at least 0.3% of the worldwide population and over 3% of those over 80 years old. According to recent research (2018), in 2016, 6.1 million (95% uncertainty interval (UI) 5.0–7.3) individuals had Parkinson’s disease globally, compared with 2.5 million (2.0–3.0) in 1990. The pandemic-like spreading of PD is considered a slow-moving disaster. Most recent studies indicated the possible role of an altered microbiome, dysbiosis, in the development of PD, which occurs long before the clinical diagnosis of PD. Antibiotics are considered as major disruptors of the intestinal flora and we have hypothesized that, as different classes of antibiotics might induce different dysbiosis, certain classes of antibiotics could trigger the PD-related dysbiosis as well. Comparative analyses were performed between the average yearly antibiotic consumption of 30 European countries (1997–2016) and the PD prevalence database (estimated for 2016). We divided the time frame of antibiotic consumption of 1997–2016 into four subsections to estimate the possible time lapse between antibiotic exposure and the prevalence, prevalence change, and PD-related death rates estimated for 2016. Our results indicated that countries with high consumption of narrow-spectrum penicillin experienced a higher increase in PD prevalence than the others. Countries reporting a decline in PD from 1990 to 2016 demonstrated a reduction in the consumption of narrow-spectrum penicillin in this period.

Depression in Parkinson's Disease: A Narrative Review

Parkinson's disease (PD) is a progressive neurodegenerative age-related disorder that affects the central nervous system (CNS) and is characterized by uncontrollable movements such as shaking, stiffness, and loss of balance and coordination. Depression is a common non-motor manifestation of PD, but unfortunately, depression remains unrecognized and often undertreated. The underlying pathophysiology of depression in PD is complicated, and many studies have been conducted to know the exact cause, but the question remains unanswered.

In this article, we discuss various pathophysiologies by which depression occurs in PD. The most widely accepted theories are neuroinflammation and monoamine oxidase theory. This article also explored the pharmacological treatment of depression in PD; this involves standard antidepressant therapy such as tricyclic antidepressants (TCA), serotonin-norepinephrine reuptake inhibitors (SNRI), selective serotonin reuptake inhibitors (SSRI), and monoamine oxidase inhibitors (MAO); non-pharmacological treatments such as electroconvulsive therapy (ECT), cognitive-behavioral therapy (CBT) have also been discussed. However, physicians hesitate to prescribe antidepressants to patients with PD due to concerns about harmful drug-drug interactions between antidepressants and antiparkinsonian drugs. Despite the complicated link between PD and depression, the co-administration of antidepressants and antiparkinsonian drugs is safe and beneficial when appropriately managed. However, early recognition and initiation of treatment of depression in PD reduces the longitudinal course and improves the cross-sectional picture. This review article also explored the clinical and diagnostic findings and impact on the quality of life of depression in PD.

Clinical Features in Parkinson's Disease Patients with Hyperechogenicity in Substantia Nigra: A Cross-Sectional Study

BACKGROUND

Transcranial ultrasound (TCS) can be used to reveal structural changes in the substantia nigra (SN) and is a potential tool for the early diagnosis of Parkinson's disease (PD). This study aimed to explore the relationship between substantia nigra hyperechogenicity (SNH) and the clinical features of PD patients.

METHODS

A total of 96 PD patients were included in our study. All patients were detected by TCS and divided into two groups: PD patients with SNH (PDSN+) and those with normal SN echogenicity (PDSN-). The Unified Parkinson's Disease Rating Scale (UPDRS) and the Hoehn & Yahr stage were used to assess the extent of disease-related disability of the PD patients. Non-motor symptoms were evaluated by using several scales. The instrumented stand and walk test was performed on all subjects, and gait data were gathered using a JiBuEn gait analysis system.

RESULTS

Seventy-five PD patients were successfully assessed by TCS. We found that SNH was associated with a higher UPDRS II scores (p = 0.028). In addition, compared with PDSN- group, the PDSN+ group exhibited more severe gait impairment, including increased variability in stride length (p = 0.042), decreased heel strike angle (p = 0.017), decreased range of motion of hip joints (p = 0.031), and a more asymmetrical walking pattern (p = 0.028).

CONCLUSION

Our study demonstrated that SNH significantly correlated with activities of daily living and gait impairment in Chinese patients with PD, suggesting the formation of SNH might be a dynamic biomarker reflecting disease severity.

Biomarkers and the Role of α-Synuclein in Parkinson's Disease

Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by the presence of α-synuclein (α-Syn)-rich Lewy bodies (LBs) and the preferential loss of dopaminergic (DA) neurons in the substantia nigra (SN) pars compacta (SNpc). However, the widespread involvement of other central nervous systems (CNS) structures and peripheral tissues is now widely documented. The onset of the molecular and cellular neuropathology of PD likely occurs decades before the onset of the motor symptoms characteristic of PD, so early diagnosis of PD and adequate tracking of disease progression could significantly improve outcomes for patients. Because the clinical diagnosis of PD is challenging, misdiagnosis is common, which highlights the need for disease-specific and early-stage biomarkers. This review article aims to summarize useful biomarkers for the diagnosis of PD, as well as the biomarkers used to monitor disease progression. This review article describes the role of α-Syn in PD and how it could potentially be used as a biomarker for PD. Also, preclinical and clinical investigations encompassing genetics, immunology, fluid and tissue, imaging, as well as neurophysiology biomarkers are discussed. Knowledge of the novel biomarkers for preclinical detection and clinical evaluation will contribute to a deeper understanding of the disease mechanism, which should more effectively guide clinical applications.

The bile acid TUDCA and neurodegenerative disorders: An overview

Bear bile has been used in Traditional Chinese Medicine for thousands of years due to its therapeutic potential and clinical applications. The tauroursodeoxycholic acid (TUDCA), one of the acids found in bear bile, is a hydrophilic bile acid and naturally produced in the liver by conjugation of taurine to ursodeoxycholic acid (UDCA). Several studies have shown that TUDCA has neuroprotective action in several models of neurodegenerative disorders (ND), including Alzheimer's disease, Parkinson's disease, and Huntington's disease, based on its potent ability to inhibit apoptosis, attenuate oxidative stress, and reduce endoplasmic reticulum stress in different experimental models of these illnesses. Our research extends the knowledge of the bile acid TUDCA actions in ND and the mechanisms and pathways involved in its cytoprotective effects on the brain, providing a novel perspective and opportunities for treatment of these diseases.

Targeted attenuation of elevated histone marks at SNCA alleviates α-synuclein in Parkinson's disease

Epigenetic deregulation of α-synuclein plays a key role in Parkinson's disease (PD). Analysis of the SNCA promoter using the ENCODE database revealed the presence of important histone post-translational modifications (PTMs) including transcription-promoting marks, H3K4me3 and H3K27ac, and repressive mark, H3K27me3. We investigated these histone marks in post-mortem brains of controls and PD patients and observed that only H3K4me3 was significantly elevated at the SNCA promoter of the substantia nigra (SN) of PD patients both in punch biopsy and in NeuN-positive neuronal nuclei samples. To understand the importance of H3K4me3 in regulation of α-synuclein, we developed CRISPR/dCas9-based locus-specific H3K4me3 demethylating system where the catalytic domain of JARID1A was recruited to the SNCA promoter. This CRISPR/dCas9 SunTag-JARID1A significantly reduced H3K4me3 at SNCA promoter and concomitantly decreased α-synuclein both in the neuronal cell line SH-SY5Y and idiopathic PD-iPSC derived dopaminergic neurons. In sum, this study indicates that α-synuclein expression in PD is controlled by SNCA's histone PTMs and modulation of the histone landscape of SNCA can reduce α-synuclein expression.

123I-Ioflupane dopamine transporter imaging (DaTSCAN) appearances in relation to emotional responsiveness, impulsivity and olfaction in suspected Parkinsonian syndrome

OBJECTIVE

The aim of our study was to ascertain relationships between DaTSCAN, olfactory loss, behavioural and subjective measurements of impulsivity and emotional responsiveness in patients with clinically suspected Parkinsonian syndrome (PS).

METHODS

A prospective study of 20 drug-naive patients with parkinsonism, underwent the University of Pennsylvania Smell Identification Test, impulsivity measurements and mood-state-questionnaires before visual and semi-quantitative DaTQUANT analyses. There were two subgroups: nine patients with scans without evidence of dopaminergic deficit (SWEDD - controls) and 11 patients with PS.

RESULTS

The PS group reported lower non-planning impulsivity than the SWEDD group (P = 0.039). A positive correlation was found between the non-planning impulsivity ratings and right anterior putamen/background (bck) ratio in PS group (r = 0.598, P = 0.068). Higher ratings of anger (r = 0.575, P = 0.016), fatigue (r = 0.746, P = 0.001), confusion (r = 0.561, P = 0.019) and depression were positively correlated with putamen/caudate ratios (R > L) on DaTSCAN. Higher self-reported arousal was associated with lower right putamen/caudate ratio (P = -0.581, P = 0.014). Only fatigue was positively correlated with putamen/bck (r = 0.564, P = 0.018). The degree of smell deficit correlated negatively with performance on reflection impulsivity tasks (r = -0.470, P = 0.049).

CONCLUSION

DaTSCAN appearances correlated with emotional dysfunction and self-reported impulsivity in patients with PS. Olfactory impairment was associated with increased reflection impulsivity and the age of patients. Higher DaTSCAN putamen/caudate ratios were associated with higher emotional responsiveness and higher non-planning impulsivity in PS patients. These preliminary findings may be relevant in clinical practice in differentiating PS from SWEDD and identifying susceptibility to impulse control disorder although larger studies are warranted.

Substantia Nigra Hyperechogenicity Reflects the Progression of Dopaminergic Neurodegeneration in 6-OHDA Rat Model of Parkinson's Disease

Parkinson’s disease (PD) is the second most common neurodegenerative disease, and there is still no effective way to stop its progress. Therefore, early detection is crucial for the prevention and the treatment of Parkinson’s disease. The current diagnosis of Parkinson’s disease, however, mainly depends on the symptoms, so it is necessary to establish a reliable imaging modality for PD diagnosis and its progression monitoring. Other studies and our previous ones demonstrated that substantia nigra hyperechogenicity (SNH) was detected by transcranial sonography (TCS) in the ventral midbrain of PD patients, and SNH is regarded as a characteristic marker of PD. The present study aimed to explore whether SNH could serve as a reliable imaging modality to monitor the progression of dopaminergic neurodegeneration of PD. The results revealed that the size of SNH was positively related with the degree of dopaminergic neuron death in PD animal models. Furthermore, we revealed that microglia activation contributed to the SNH formation in substantia nigra (SN) in PD models. Taken together, this study suggests that SNH through TCS is a promising imaging modality to monitor the progression of dopaminergic neurodegeneration of PD.

Subtle gait and balance impairments occur in idiopathic rapid eye movement sleep behavior disorder

BACKGROUND

Although motor abnormalities have been flagged as potentially the most sensitive and specific clinical features for predicting the future progression to Parkinson's disease, little work has been done to characterize gait and balance impairments in idiopathic rapid eye movement sleep behavior disorder (iRBD).

OBJECTIVE

The objective of this study was to quantitatively determine any static balance as well as gait impairments across the 5 independent domains of gait in polysomnography-confirmed iRBD patients using normal, fast-paced, and dual-task walking conditions.

METHODS

A total of 38 participants (24 iRBD, 14 healthy controls) completed the following 5 different walking trials across a pressure sensor carpet: (1) normal pace, (2) fast pace, (3) while counting backward from 100 by 1s, (4) while naming as many animals as possible, (5) while subtracting 7s from 100.

RESULTS

Although no gait differences were found between the groups during normal walking, there were significant differences between groups under the fast-paced and dual-task gait conditions. Specifically, in response to the dual tasking, healthy controls widened their step width without changing step width variability, whereas iRBD patients did not widen their step width but, rather, significantly increased their step width variability. Similarly, changes between the groups were observed during fast-paced walking wherein the iRBD patients demonstrated greater step length asymmetry when compared with controls.

CONCLUSIONS

This study demonstrates that iRBD patients have subtle gait impairments, which likely reflect early progressive degeneration in brainstem regions that regulate both REM sleep and gait coordination. Such gait assessments may be useful as a diagnostic preclinical screening tool for future fulminant gait abnormalities for trials of disease-preventive agents. © 2019 International Parkinson and Movement Disorder Society.

Animal models of olfactory dysfunction in neurodegenerative diseases

Olfactory dysfunction seems to occur earlier than classic motor and cognitive symptoms in many neurodegenerative diseases, including Parkinson's disease (PD) and Alzheimer's disease (AD). Thus, the use of the olfactory system as a clinical marker for neurodegenerative diseases is helpful in the characterization of prodromal stages of these diseases, early diagnostic strategies, differential diagnosis, and, potentially, prediction of treatment success. The use of genetic and neurotoxin animal models has contributed to the understanding of the mechanisms underlying olfactory dysfunction in a number of neurodegenerative diseases. In this chapter, we provide an overview of behavioral and neurochemical alterations observed in animal models of different neurodegenerative diseases (such as genetic and Aβ infusion models for AD and neurotoxins and genetic models of PD), in which olfactory dysfunction has been described.

Exercise as a therapeutic intervention for motor and non-motor symptoms in Parkinson's disease: Evidence from rodent models

Parkinson's disease (PD) is characterised by degeneration of dopaminergic neurons of the nigrostriatal pathway, which leads to the cardinal motor symptoms of the disease - tremor, rigidity and postural instability. A number of non-motor symptoms are also associated with PD, including cognitive impairment, mood disturbances and dysfunction of gastrointestinal and autonomic systems. Current therapies provide symptomatic relief but do not halt the disease process, so there is an urgent need for preventative strategies. Lifestyle interventions such as aerobic exercise have shown potential to lower the risk of developing PD and to alleviate both motor and non-motor symptoms. However, there is a lack of large-scale randomised clinical trials that have employed exercise in PD patients. This review will focus on the evidence from studies on rodent models of PD, for employing exercise as an intervention for both motor and non-motor symptoms.

Neurofilament light: A candidate biomarker of presymptomatic amyotrophic lateral sclerosis and phenoconversion

OBJECTIVE

To evaluate neurofilament light (NfL) as a biomarker of the presymptomatic phase of amyotrophic lateral sclerosis (ALS).

METHODS

The study population includes 84 individuals at risk for developing ALS, 34 controls, 17 ALS patients, and 10 phenoconverters (at-risk individuals observed both before and after the emergence of clinically manifest disease). At-risk individuals are enrolled through Pre-Symptomatic Familial ALS (Pre-fALS), a longitudinal natural history and biomarker study of individuals who are carriers of any ALS-associated gene mutation (in SOD1, C9orf72, TARDBP, FUS, VCP, etc), but who, at the time of enrollment, demonstrated no clinical symptoms or signs (including electromyographic evidence) of manifest disease. NfL in serum and cerebrospinal fluid (CSF) were quantified using an electrochemiluminescence immunoassay.

RESULTS

Serum and CSF NfL are substantially higher in ALS patients compared to controls and at-risk individuals and remain relatively stable over time. Among phenoconverters, however, NfL levels were elevated (ie, above the range observed in controls) as far back as ∼12 months preceding the emergence of the earliest clinical symptoms or signs of disease.

INTERPRETATION

Serum (and CSF) NfL are informative biomarkers of presymptomatic ALS, providing a new tool to quantify presymptomatic disease progression and to potentially predict the timing of clinical phenoconversion. As such, quantification of NfL may aid the design and implementation of early therapeutic intervention for affected individuals and/or disease prevention trials for individuals at short-term risk of developing ALS. Ann Neurol 2018 Ann Neurol 2018;83:130-139.

A predictive model to identify Parkinson disease from administrative claims data

OBJECTIVE

To use administrative medical claims data to identify patients with incident Parkinson disease (PD) prior to diagnosis.

METHODS

Using a population-based case-control study of incident PD in 2009 among Medicare beneficiaries aged 66-90 years (89,790 cases, 118,095 controls) and the elastic net algorithm, we developed a cross-validated model for predicting PD using only demographic data and 2004-2009 Medicare claims data. We then compared this model to more basic models containing only demographic data and diagnosis codes for constipation, taste/smell disturbance, and REM sleep behavior disorder, using each model's receiver operator characteristic area under the curve (AUC).

RESULTS

We observed all established associations between PD and age, sex, race/ethnicity, tobacco smoking, and the above medical conditions. A model with those predictors had an AUC of only 0.670 (95% confidence interval [CI] 0.668-0.673). In contrast, the AUC for a predictive model with 536 diagnosis and procedure codes was 0.857 (95% CI 0.855-0.859). At the optimal cut point, sensitivity was 73.5% and specificity was 83.2%.

CONCLUSIONS

Using only demographic data and selected diagnosis and procedure codes readily available in administrative claims data, it is possible to identify individuals with a high probability of eventually being diagnosed with PD.

The BSSG rat model of Parkinson's disease: progressing towards a valid, predictive model of disease

ABSTRACT

Parkinson's disease (PD) is a neurodegenerative disorder, classically considered a movement disorder. A great deal is known about the anatomical connections and neuropathology and pharmacological changes of PD, as they relate to the loss of dopaminergic function and the appearance of cardinal motor symptoms. Our understanding of the role of dopamine in PD has led to the development of effective pharmacological treatments of the motor symptoms in the form of dopamine replacement therapy using levodopa and dopaminergic agonists. Much of the information concerning these drug treatments has been obtained using classical neurotoxic models that mimic dopamine depletion (e.g., 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine or MPTP, 6-hydroxydopamine, reserpine). However, PD is more than a disorder of the nigrostriatal dopamine pathway. Our understanding of the neuropathology of PD has undergone massive changes, with the discovery that mutations in α-synuclein cause a familial form of PD and that PD pathology may spread, affecting multiple neurotransmitter systems and brain regions. These new developments in our understanding of PD demand that we reconsider our animal models. While classic neurotoxin models have been useful for the development of effective symptomatic treatments for motor manifestations, the paucity of a valid animal model exhibiting the progressive development of multiple key features of PD pathophysiology and phenotype has impeded the search for neuroprotective therapies, capable of slowing or halting disease progression.

RELEVANCE OF THE ARTICLE FOR PREDICTIVE PREVENTIVE AND PERSONALISED MEDICINE

What characteristics would a good animal model of human PD have? In so much as is possible, a good model would exhibit as many behavioral, anatomical, biochemical, immunological, and pathological changes as are observed in the human condition, developing progressively, with clear, identifiable biomarkers along the way. Here, we review the BSSG rat model of PD, a novel environmental model of PD, with strong construct, face, and predictive validity. This model offers an effective tool for the screening of preventive therapies that may prove to be more predictive of their effects in human patients.

Deregulation of α-synuclein in Parkinson's disease: Insight from epigenetic structure and transcriptional regulation of SNCA

Understanding regulation of α-synuclein has long been a central focus for Parkinson's disease (PD) researchers. Accumulation of this protein in the Lewy body or neurites, mutations in the coding region of the gene and strong association of α-synuclein encoding gene multiplication (duplication/triplication) with familial form of PD have indicated the importance of this molecule in pathogenesis of the disease. Several years of research identified many potential faulty pathways associated with accumulation of α-synuclein inside dopaminergic neurons and its transmission to neighboring ones. Concurrently, an appreciable body of research is growing to understand the epigenetic and genetic deregulation of α-synuclein that might contribute to the disease pathology. Completion of the ENCODE (Encyclopedia of DNA Elements) project and recent advancement made in the epigenetic and trans factor mediated regulation of each gene, has tremendously accelerated the need to carefully understand the epigenetic structure of the gene (SNCA) encoding α-synuclein protein in order to decipher the regulation and contribution of α-synuclein to the pathogenesis of PD. We have also analyzed the detailed epigenetic structure of this gene with knowledge from ENCODE database, which may open new avenues in α-synuclein research. Interestingly, we have found that the gene contains several transcriptionally activate histone modifications and associated potential transcription factor binding sites in the non-coding areas that strongly suggest alternative regulatory pathways. Altogether this review will provide interesting insight of α-synuclein gene regulation from epigenetic, genetic and post-transcriptional perspectives and their potential implication in the PD pathogenesis.

Olfactory dysfunction and dementia in newly diagnosed patients with Parkinson's disease

INTRODUCTION

Studies report that up to 90% of patients with idiopathic Parkinson's disease (PD) have olfactory dysfunction (hyposmia). Hyposmia has also been connected to cognitive impairment and dementia in PD, but no studies of newly diagnosed patients followed longer than three years exists. The present study investigates the prevalence of olfactory dysfunction at PD diagnosis, how it evolves over time and whether hyposmia increases the risk of dementia in Parkinson's disease.

METHODS

Olfactory function was assessed with Brief Smell Identification Test (B-SIT) in 125 newly diagnosed patients with PD. They were followed for a maximum of 10 years (median six years) with extensive investigations at baseline, 12, 36, 60 and 96 months. Patients with B-SIT<9 were considered hyposmic.

RESULTS

Hyposmia was found in 73% of the patients at diagnosis. During the follow up period of ten years 42 (46%) patients with hyposmia at baseline developed dementia compared to seven (21%) of the normosmic patients. Cox proportional hazards model showed that hyposmia at baseline (controlled for age, gender, UPDRS III and Mild Cognitive Impairment) increased the risk of developing dementia (hazard ratio (95%CI): 3.29 (1.44-7.52), p = 0.005). Only one of 22 patients with normal cognition and normal olfaction at baseline developed dementia.

CONCLUSIONS

Olfactory dysfunction was common at the time of PD diagnosis and increased the risk of dementia up to ten years after PD diagnosis regardless of baseline cognitive function. Normal olfaction together with normal cognition at baseline predicted a benign cognitive course up to ten years after diagnosis.

Basal ganglia dysfunction in idiopathic REM sleep behaviour disorder parallels that in early Parkinson's disease

See Postuma (doi:10.1093/aww131) for a scientific commentary on this article.

Resting state functional magnetic resonance imaging dysfunction within the basal ganglia network is a feature of early Parkinson’s disease and may be a diagnostic biomarker of basal ganglia dysfunction. Currently, it is unclear whether these changes are present in so-called idiopathic rapid eye movement sleep behaviour disorder, a condition associated with a high rate of future conversion to Parkinson’s disease. In this study, we explore the utility of resting state functional magnetic resonance imaging to detect basal ganglia network dysfunction in rapid eye movement sleep behaviour disorder. We compare these data to a set of healthy control subjects, and to a set of patients with established early Parkinson’s disease. Furthermore, we explore the relationship between resting state functional magnetic resonance imaging basal ganglia network dysfunction and loss of dopaminergic neurons assessed with dopamine transporter single photon emission computerized tomography, and perform morphometric analyses to assess grey matter loss. Twenty-six patients with polysomnographically-established rapid eye movement sleep behaviour disorder, 48 patients with Parkinson’s disease and 23 healthy control subjects were included in this study. Resting state networks were isolated from task-free functional magnetic resonance imaging data using dual regression with a template derived from a separate cohort of 80 elderly healthy control participants. Resting state functional magnetic resonance imaging parameter estimates were extracted from the study subjects in the basal ganglia network. In addition, eight patients with rapid eye movement sleep behaviour disorder, 10 with Parkinson’s disease and 10 control subjects received ¹²³I-ioflupane single photon emission computerized tomography. We tested for reduction of basal ganglia network connectivity, and for loss of tracer uptake in rapid eye movement sleep behaviour disorder and Parkinson’s disease relative to each other and to controls. Connectivity measures of basal ganglia network dysfunction differentiated both rapid eye movement sleep behaviour disorder and Parkinson’s disease from controls with high sensitivity (96%) and specificity (74% for rapid eye movement sleep behaviour disorder, 78% for Parkinson’s disease), indicating its potential as an indicator of early basal ganglia dysfunction. Rapid eye movement sleep behaviour disorder was indistinguishable from Parkinson’s disease on resting state functional magnetic resonance imaging despite obvious differences on dopamine transported single photon emission computerized tomography. Basal ganglia connectivity is a promising biomarker for the detection of early basal ganglia network dysfunction, and may help to identify patients at risk of developing Parkinson’s disease in the future. Future risk stratification using a polymodal approach could combine basal ganglia network connectivity with clinical and other imaging measures, with important implications for future neuroprotective trials in rapid eye movement sleep behaviour disorder.

Metacognitive knowledge of olfactory dysfunction in Parkinson's disease

It is well known that patients with Parkinson's Disease (PD) suffer from olfactory impairments, but it is not clear whether patients are aware of their level of deficit in olfactory functioning. Since PD is a neurodegenerative disorder and its progression may be correlated with olfactory loss (Ansari & Johnson, 1975; but see also Doty, Deems, & Stellar, 1988), it is possible that these patients would be subject to metacognitive errors of over-estimation of olfactory ability (White & Kurtz, 2003). Nineteen non-demented PD patients and 19 age-matched controls were each given an objective measure of olfactory identification (the UPSIT, Doty, Shaman, Kimmelman, & Dann, 1984) and a subjective measure involving a questionnaire that asked them to self-rate both their olfactory function generally and their ability to smell each of 20 odors, 12 of which were assessed on the UPSIT. All of the PD patients showed impaired olfactory ability, as did 7 of the controls, according to the UPSIT norms. Self-rated and performance-based olfactory ability scores were significantly correlated in controls (r=.49, p=.03) but not in patients with PD (r=.20, p=.39). When the 12 odors common to both the self-rated questionnaire and UPSIT were compared, PD patients were less accurate than controls (t(36)=-4.96, p<.01) at estimating their own ability and the number of over-estimation errors was significantly higher (tone-tailed(29)=1.80, p=.04) in PD patients than in the control group, showing less metacognitive awareness of their ability than controls. These results support the idea that olfactory metacognition is often impaired in PD, as well as in controls recruited for normosmic ability (Wehling, Nordin, Espeseth, Reinvang, & Lundervold, 2011), and indicate that people with PD generally exhibit over-estimation of their olfactory ability at a rate that is higher than controls. These findings imply that PD patients, unaware of their olfactory deficit, are at greater risk of harm normally detected through olfaction, such as smoke or spoiled foods.

Neurophysiological basis of rapid eye movement sleep behavior disorder: informing future drug development

Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia characterized by a history of recurrent nocturnal dream enactment behavior and loss of skeletal muscle atonia and increased phasic muscle activity during REM sleep: REM sleep without atonia. RBD and associated comorbidities have recently been identified as one of the most specific and potentially sensitive risk factors for later development of any of the alpha-synucleinopathies: Parkinson's disease, dementia with Lewy bodies, and other atypical parkinsonian syndromes. Several other sleep-related abnormalities have recently been identified in patients with RBD/Parkinson's disease who experience abnormalities in sleep electroencephalographic frequencies, sleep-wake transitions, wake and sleep stability, occurrence and morphology of sleep spindles, and electrooculography measures. These findings suggest a gradual involvement of the brainstem and other structures, which is in line with the gradual involvement known in these disorders. We propose that these findings may help identify biomarkers of individuals at high risk of subsequent conversion to parkinsonism.

Reasons for mild parkinsonian signs - which constellation may indicate neurodegeneration?

INTRODUCTION

Mild parkinsonian signs (MPS) are common in the elderly population. Several factors including physical decline and comorbidities in addition to neurodegeneration may be possible sources for MPS. The objective was to examine whether MPS are associated with a history of orthopedic disturbances, vascular diseases or prodromal markers for neurodegeneration.

METHODS

The TREND study is a prospective longitudinal cohort study in individuals >50 years with biennial assessments designed to identify prodromal markers for neurodegeneration. In this substudy, 1091 elderly individuals were evaluated for a possible association of MPS with prodromal markers for neurodegeneration, orthopedic disturbances, vascular diseases, as well as cerebral abnormalities. These factors were assessed by self-administered questionnaires, with a structured health interview, a neurological examination and by transcranial sonography.

RESULTS

82 participants showed MPS. They were found to have more often hyposmia and RBD, had a higher autonomic dysfunction score and they more frequently showed hyperechogenicity of the substantia nigra compared to controls. Neither orthopedic disturbances nor vascular diseases were significantly associated with the prevalence of MPS.

CONCLUSION

MPS might be a sign of early neurodegeneration rather than caused by other motor influencing diseases.

A novel treatment target for Parkinson's disease

We hypothesize that GPR109A message and expression are up-regulated in individuals with Parkinson's disease (PD). GPR109A is a high-affinity niacin receptor. Niacin is a precursor for NAD-NADH which is needed for dopamine production. Thus, niacin supplementation may serve three purposes: reduce inflammation through GPR109A-related mechanisms, increase dopamine synthesis in the striatum through NADPH supply and increase NAD/NADH ratio to boost mitochondrial functions. GPR109A and its agonists are known to exert anti-inflammatory actions in the skin, gut and retina. However these roles are neither anticipated nor established in the CNS. For the first time here we propose the roles of GPR109A and its agonists including niacin in CNS pathology. Moreover we predict that the neuroprotective roles of either niacin or butyrates in CNS occur via GPR109A.

Investigating the night-to-night variability of REM without atonia in Parkinson's disease

OBJECTIVES

Rapid eye movement (REM) sleep behaviour disorder is frequently observed in Parkinson's disease and is characterized electrophysiologically by the absence of atonia during REM sleep. However, the night-to-night variability of REM sleep without atonia is yet to be determined in Parkinson's disease.

METHODS

Using polysomnography, this study measured the variability of REM sleep without atonia across two consecutive nights, using the REM atonia index in 38 patients with Parkinson's disease.

RESULTS

The intraclass correlation coefficient between the REM sleep atonia index across two nights was 0.816 (F = 9.795, p < 0.001) and the difference between the two nights was 4.7% (standard deviation (SD) 8.2).

CONCLUSION

The REM atonia index demonstrated low variability across two consecutive nights of PSG. Furthermore, the diagnosis of REM sleep behaviour disorder based on this electrophysiological marker and other clinical variables was in agreement across the two nights.

Nonmotor symptoms in a malaysian Parkinson's disease population

Background. The nonmotor symptoms are important determinants of health and quality of life in Parkinson's disease but are not well recognized and addressed in clinical practice. This study was conducted to determine the prevalence of nonmotor symptoms and their impact on quality of life in patients with Parkinson's disease. Methods. This was a cross-sectional study among patients with idiopathic Parkinson's disease. Exclusion criteria were a Mini Mental State Examination score of <21/30. Prevalence of nonmotor symptoms was determined using the NMSQuest. The severity of nonmotor symptoms and the quality of life were assessed using validated disease-specific questionnaires (PDQ-39 and NMSS). Results. A total of 113 patients consisting of 60 males and 53 females were recruited. The median duration of illness was 5.0 (2.0-8.0) years. The prevalence rate of nonmotor symptoms in our cohort was 97.3%. The most common reported nonmotor symptom in our cohort was gastrointestinal (76.1%). We found that the severity of the nonmotor symptoms was associated with poorer quality of life scores (r s : 0.727, P < 0.001). Conclusions. Nonmotor symptoms were highly prevalent in our patients with Parkinson's disease and adversely affected the quality of life of our patients. In contrast to western studies, the most common nonmotor symptom is gastrointestinal. The possibility of an Asian diet playing a role in this observation requires further study.

Mild parkinsonian signs in the elderly--is there an association with PD? Crossectional findings in 992 individuals

Background

Mild parkinsonian signs (MPS) are common in the elderly population, and have been associated with vascular diseases, mild cognitive impairment and dementia; however their relation to Parkinson's disease (PD) is unclear. Hypothesizing that individuals with MPS may reflect a pre-stage of PD, i.e. a stage in which the nigrostriatal system is already affected although to a milder degree than at the time of PD diagnosis, aim of this study was to evaluate the similarities between MPS and PD.

Methods

The TREND study is a prospective cross-sectional cohort study in individuals >50 years with biennial assessments designed to identify markers for an earlier diagnosis of Parkinson's and Alzheimer's disease. For this substudy 992 individuals were included for analyses (892 controls, 73 MPS individuals, 27 PD patients). Parameters defining risk of PD (sex, age, positive family history), prodromal markers (hyposmia, REM sleep behavior disorder, depression and autonomic failure) as well as quantitative fine motor, axial motor and cognitive parameters were compared between the three cohorts.

Results

As expected, PD patients differed from controls with regard to 12 of 15 of the assessed parameters. MPS individuals differed significantly from controls in 12 of the PD-associated parameters, but differed from PD only in 5 parameters.

Conclusion

This study shows that individuals with MPS share many prodromal and clinical markers of PD with PD patients, implying that either a common dynamic process or similar constitutional factors occur in MPS individuals and PD patients.

Investigating rapid eye movement sleep without atonia in Parkinson's disease using the rapid eye movement sleep behavior disorder screening questionnaire

Rapid eye movement (REM) sleep behavior disorder (RBD) is frequently observed in patients with Parkinson's disease (PD). Accurate diagnosis is essential for managing this condition. Furthermore, the emergence of idiopathic RBD in later life can represent a premotor feature, heralding the development of PD. Reliable, accurate methods for identifying RBD may offer a window for early intervention. This study sought to identify whether the RBD screening questionnaire (RBDSQ) and three questionnaires focused on dream enactment were able to correctly identify patients with REM without atonia (RWA), the neurophysiological hallmark of RBD. Forty-six patients with PD underwent neurological and sleep assessment in addition to completing the RBDSQ, the RBD single question (RBD1Q), and the Mayo Sleep Questionnaire (MSQ). The REM atonia index was derived for all participants as an objective measure of RWA. Patients identified to be RBD positive on the RBDSQ did not show increased RWA on polysomnography (80% sensitivity and 55% specificity). However, patients positive for RBD on questionnaires specific to dream enactment correctly identified higher degrees of RWA and improved the diagnostic accuracy of these questionnaires. This study suggests that the RBDSQ does not accurately identify RWA, essential for diagnosing RBD in PD. Furthermore, the results suggest that self-report measures of RBD need to focus questions on dream enactment behavior to better identify RWA and RBD. Further studies are needed to develop accurate determination and quantification of RWA in RBD to improve management of patients with PD in the future.

Postural sway in idiopathic rapid eye movement sleep behavior disorder: a potential marker of prodromal Parkinson's disease

There is compelling evidence that postural instability occurs at very early clinical stages of Parkinson's disease (PD), making it tempting to speculate that changes in postural sway may even occur at a prodromal phase. Studies estimate that approximately half of patients with idiopathic rapid eye movement (REM) sleep behavior disorder (RBD) will eventually develop PD, so RBD may be an indicator of prodromal PD. This study was undertaken to investigate postural sway and its relation to stereopsis function in patients with RBD. We examined 24 patients with polysomnography-confirmed RBD and 23 healthy, sex-and age-matched control subjects. Postural sway was measured with an accelerometer at the center of mass at the lower spine. Subjects were asked to stand quietly for 30s under two usual conditions (eyes open and eyes closed) and three challenging conditions (eyes open with dual task, eyes closed with dual task, and tandem standing). Stereopsis was assessed using the Titmus fly test. RBD patients showed an increased variability of trunk acceleration and a decrease of smoothness of sway, compared to control subjects. These differences reached significance in the challenging conditions. RBD patients demonstrated significant impairment in stereopsis. There were statistically significant correlations between log seconds of arc of the Titmus test and some sway parameters within the RBD group. RBD patients with abnormal stereopsis showed a significant increase of JERK values compared to patients with normal stereopsis in the challenging conditions. Our results indicate that idiopathic RBD patients, especially with abnormal stereopsis, have subtle signs of postural instability under challenging conditions. Postural sway performance may serve as a biological marker for prodromal PD.

Prodromal features for Parkinson's disease--baseline data from the TREND study

BACKGROUND AND PURPOSE

A number of non-motor features are known to precede motor manifestations of Parkinson's disease (PD). They are supposed to already represent the prodromal neurodegenerative state in those who later develop PD and are thus called prodromal markers. In this study, three prodromal markers, depression, rapid eye movement behaviour disorder (RBD) and hyposmia, were selected and were related to other prodromal features in elderly individuals without PD.

METHODS

From the Tübinger Evaluation of Risk Factors for Early Detection of Neurodegeneration (TREND) study, 698 healthy individuals aged 50-80 years reporting one or more of the selected prodromal markers (SPMs), but without neurodegenerative disorders, were evaluated and classified according to the status of prodromal markers. Other prodromal PD-related features were assessed with a 23-item questionnaire and compared between participants with and without the three SPMs.

RESULTS

Individuals with the SPMs for PD endorsed more of the additional possible prodromal features of PD than those without; of 23 possible prodromal features, the median number identified amongst participants with no SPMs was two, compared with four with one marker, five with two and seven with three (P < 0.001). Regarding individual SPMs, participants with depression and RBD endorsed five of 23 markers, compared with three for those with hyposmia (P = 0.001). There was no significant increase in the number of prodromal features amongst those with two SPMs compared with those with only one marker.

CONCLUSIONS

Individuals with the SPMs for PD report a higher prevalence of other prodromal PD symptoms. This may indicate that these markers can identify individuals at risk for PD.

Panax ginseng is neuroprotective in a novel progressive model of Parkinson's disease

Panax ginseng has been used in traditional Chinese medicine for centuries. Among its various benefits is a pluripotent targeting of the various events involved in neuronal cell death. This includes anti-inflammatory, anti-oxidant, and anti-apoptotic effects. Indeed, ginseng extract and its individual ginsenosides have been demonstrated to influence a number of biochemical markers implicated in Parkinson's disease (PD) pathogenesis. We have reported previously that administration of the ginseng extract, G115, afforded robust neuroprotection in two rodent models of PD. However, these traditional rodent models are acute in nature and do accurately recapitulate the progressive nature of the disease. Chronic exposure to the dietary phytosterol glucoside, β-sitosterol β-d-glucoside (BSSG) triggers the progressive development of neurological deficits, with behavioral and cellular features that closely approximate those observed in PD patients. Clinical signs and histopathology continue to develop for several months following cessation of exposure to the neurotoxic insult. Here, we utilized this model to further characterize the neuroprotective effects of the ginseng extract, G115. Oral administration of this extract significantly reduced dopaminergic cell loss, microgliosis, and accumulation of α-synuclein aggregates. Further, G115 administration fully prevented the development of locomotor deficits, in the form of reduced locomotor activity and coordination. These results suggest that ginseng extract may be a potential neuroprotective therapy for the treatment of PD.

A review of quality of life after predictive testing for and earlier identification of neurodegenerative diseases

The past decade has witnessed an explosion of evidence suggesting that many neurodegenerative diseases can be detected years, if not decades, earlier than previously thought. To date, these scientific advances have not provoked any parallel translational or clinical improvements. There is an urgency to capitalize on this momentum so earlier detection of disease can be more readily translated into improved health-related quality of life for families at risk for, or suffering with, neurodegenerative diseases. In this review, we discuss health-related quality of life (HRQOL) measurement in neurodegenerative diseases and the importance of these "patient reported outcomes" for all clinical research. Next, we address HRQOL following early identification or predictive genetic testing in some neurodegenerative diseases: Huntington disease, Alzheimer's disease, Parkinson's disease, Dementia with Lewy bodies, frontotemporal dementia, amyotrophic lateral sclerosis, prion diseases, hereditary ataxias, Dentatorubral-pallidoluysian atrophy and Wilson's disease. After a brief report of available direct-to-consumer genetic tests, we address the juxtaposition of earlier disease identification with assumed reluctance toward predictive genetic testing. Forty-one studies examining health-related outcomes following predictive genetic testing for neurodegenerative disease suggested that (a) extreme or catastrophic outcomes are rare; (b) consequences commonly include transiently increased anxiety and/or depression; (c) most participants report no regret; (d) many persons report extensive benefits to receiving genetic information; and (e) stigmatization and discrimination for genetic diseases are poorly understood and policy and laws are needed. Caution is appropriate for earlier identification of neurodegenerative diseases but findings suggest further progress is safe, feasible and likely to advance clinical care.

Antidepressants and REM sleep behavior disorder: isolated side effect or neurodegenerative signal?

OBJECTIVES

Antidepressants, among the most commonly prescribed medications, trigger symptoms of REM sleep behavior disorder (RBD) in up to 6% of users. Idiopathic RBD is a very strong prodromal marker of Parkinson disease and other synuclein-mediated neurodegenerative syndromes. It is therefore critically important to understand whether antidepressant-associated RBD is an independent pharmacologic syndrome or a sign of possible prodromal neurodegeneration.

DESIGN

Prospective cohort study.

SETTING

Tertiary sleep disorders center.

PARTICIPANTS

100 patients with idiopathic RBD, all with diagnosis confirmed on polysomnography, stratified to baseline antidepressant use, with 45 matched controls.

MEASUREMENTS/RESULTS

Of 100 patients, 27 were taking antidepressants. Compared to matched controls, RBD patients taking antidepressants demonstrated significant abnormalities of 12/14 neurodegenerative markers tested, including olfaction (P = 0.007), color vision (P = 0.004), Unified Parkinson Disease Rating Scale II and III (P < 0.001 and 0.007), timed up-and-go (P = 0.003), alternate tap test (P = 0.002), Purdue Pegboard (P = 0.007), systolic blood pressure drop (P = 0.029), erectile dysfunction (P = 0.002), constipation (P = 0.003), depression indices (P < 0.001), and prevalence of mild cognitive impairment (13% vs. 60%, P < 0.001). All these abnormalities were indistinguishable in severity from RBD patients not taking antidepressants. However, on prospective follow-up, RBD patients taking antidepressants had a lower risk of developing neurodegenerative disease than those without antidepressant use (5-year risk = 22% vs. 59%, RR = 0.22, 95%CI = 0.06, 0.74).

CONCLUSIONS

Although patients with antidepressant-associated RBD have a lower risk of neurodegeneration than patients with "purely-idiopathic" RBD, markers of prodromal neurodegeneration are still clearly present. Development of RBD with antidepressants can be an early signal of an underlying neurodegenerative disease.

Biomarkers in Parkinson's disease (recent update)

Parkinson's disease (PD) is the second most common neurodegenerative disorder mostly affecting the aging population over sixty. Cardinal symptoms including, tremors, muscle rigidity, drooping posture, drooling, walking difficulty, and autonomic symptoms appear when a significant number of nigrostriatal dopaminergic neurons are already destroyed. Hence we need early, sensitive, specific, and economical peripheral and/or central biomarker(s) for the differential diagnosis, prognosis, and treatment of PD. These can be classified as clinical, biochemical, genetic, proteomic, and neuroimaging biomarkers. Novel discoveries of genetic as well as nongenetic biomarkers may be utilized for the personalized treatment of PD during preclinical (premotor) and clinical (motor) stages. Premotor biomarkers including hyper-echogenicity of substantia nigra, olfactory and autonomic dysfunction, depression, hyposmia, deafness, REM sleep disorder, and impulsive behavior may be noticed during preclinical stage. Neuroimaging biomarkers (PET, SPECT, MRI), and neuropsychological deficits can facilitate differential diagnosis. Single-cell profiling of dopaminergic neurons has identified pyridoxal kinase and lysosomal ATPase as biomarker genes for PD prognosis. Promising biomarkers include: fluid biomarkers, neuromelanin antibodies, pathological forms of α-Syn, DJ-1, amyloid β and tau in the CSF, patterns of gene expression, metabolomics, urate, as well as protein profiling in the blood and CSF samples. Reduced brain regional N-acetyl-aspartate is a biomarker for the in vivo assessment of neuronal loss using magnetic resonance spectroscopy and T2 relaxation time with MRI. To confirm PD diagnosis, the PET biomarkers include [(18)F]-DOPA for estimating dopaminergic neurotransmission, [(18)F]dG for mitochondrial bioenergetics, [(18)F]BMS for mitochondrial complex-1, [(11)C](R)-PK11195 for microglial activation, SPECT imaging with (123)Iflupane and βCIT for dopamine transporter, and urinary salsolinol and 8-hydroxy, 2-deoxyguanosine for neuronal loss. This brief review describes the merits and limitations of recently discovered biomarkers and proposes coenzyme Q10, mitochondrial ubiquinone-NADH oxidoreductase, melatonin, α-synculein index, Charnoly body, and metallothioneins as novel biomarkers to confirm PD diagnosis for early and effective treatment of PD.

Delayed emergence of a parkinsonian disorder or dementia in 81% of older men initially diagnosed with idiopathic rapid eye movement sleep behavior disorder: a 16-year update on a previously reported series

OBJECTIVE

To provide a 16-year update from the authors' 1996 report documenting a 38% conversion from idiopathic rapid eye movement sleep behavior disorder (iRBD) to a parkinsonian disorder at a mean interval of nearly 13 years after the onset of iRBD in a series of 29 males > or =50 years old.

METHODS

The methods of evaluation, diagnosis and follow-up were previously described in the 1996 report. All patients had video-polysomnography (vPSG) confirmed RBD.

RESULTS

80.8% (21/26) of patients who were initially diagnosed with iRBD eventually developed parkinsonism/dementia (three of the original 29 patients were lost to follow-up). The distribution of diagnoses was as follows: n=13, Parkinson's disease (PD); n=3, dementia with Lewy bodies (DLB); n=1, dementia (unspecified; profound); n=2, multiple system atrophy (MSA); n=2, clinically diagnosed Alzheimer's Disease (AD) with autopsy-confirmed combined AD plus Lewy body disease pathology. Among the 21 iRBD "converters," the mean age (±SD) of iRBD onset was 57.7±7.7 years; mean age (±SD) of parkinsonism/dementia onset was 71.9±6.6 years; and mean interval (±SD) from iRBD onset to parkinsonism/dementia onset was 14.2±6.2 years (range: 5-29 years).

CONCLUSION

The vast majority of men > or =50 years old initially diagnosed with iRBD in this study eventually developed a parkinsonian disorder/dementia, often after a prolonged interval from onset of iRBD, with the mean interval being 14 years while the range extended to 29 years. Also, the specificity of iRBD converting to parkinsonism/dementia is striking. These findings carry important clinical and research implications in the convergent fields of sleep medicine, neurology, and neuroscience, and identify an optimal clinical group for conducting prospective research studies utilizing putative neuroprotective agents to delay the emergence of, or halt the progression to, parkinsonism and/or cognitive impairment as manifestations of either PD, DLB or MSA.

The neurobiology of glucocerebrosidase-associated parkinsonism: a positron emission tomography study of dopamine synthesis and regional cerebral blood flow

Mutations in GBA, the gene encoding glucocerebrosidase, the enzyme deficient in Gaucher disease, are common risk factors for Parkinson disease, as patients with Parkinson disease are over five times more likely to carry GBA mutations than healthy controls. Patients with GBA mutations generally have an earlier onset of Parkinson disease and more cognitive impairment than those without GBA mutations. We investigated whether GBA mutations alter the neurobiology of Parkinson disease, studying brain dopamine synthesis and resting regional cerebral blood flow in 107 subjects (38 women, 69 men). We measured dopamine synthesis with (18)F-fluorodopa positron emission tomography, and resting regional cerebral blood flow with H(2)(15)O positron emission tomography in the wakeful, resting state in four study groups: (i) patients with Parkinson disease and Gaucher disease (n = 7, average age = 56.6 ± 9.2 years); (ii) patients with Parkinson disease without GBA mutations (n = 11, 62.1 ± 7.1 years); (iii) patients with Gaucher disease without parkinsonism, but with a family history of Parkinson disease (n = 14, 52.6 ± 12.4 years); and (iv) healthy GBA-mutation carriers with a family history of Parkinson disease (n = 7, 50.1 ± 18 years). We compared each study group with a matched control group. Data were analysed with region of interest and voxel-based methods. Disease duration and Parkinson disease functional and staging scores were similar in the two groups with parkinsonism, as was striatal dopamine synthesis: both had greatest loss in the caudal striatum (putamen Ki loss: 44 and 42%, respectively), with less reduction in the caudate (20 and 18% loss). However, the group with both Parkinson and Gaucher diseases showed decreased resting regional cerebral blood flow in the lateral parieto-occipital association cortex and precuneus bilaterally. Furthermore, two subjects with Gaucher disease without parkinsonian manifestations showed diminished striatal dopamine. In conclusion, the pattern of dopamine loss in patients with both Parkinson and Gaucher disease was similar to sporadic Parkinson disease, indicating comparable damage in midbrain neurons. However, H(2)(15)O positron emission tomography studies indicated that these subjects have decreased resting activity in a pattern characteristic of diffuse Lewy body disease. These findings provide insight into the pathophysiology of GBA-associated parkinsonism.

Rapid eye movement sleep behavior disorder as a biomarker for neurodegeneration: the past 10 years

Since its original description, idiopathic rapid eye movement sleep behavior disorder (RBD) has become a well-established risk factor for neurodegenerative disease. Studies from sleep centers have found that at least 40-65% of patients with idiopathic RBD will develop a defined neurodegenerative phenotype over 10 years. This elevated risk of neurodegeneration has been recently confirmed in a population-based study of probable RBD. When a defined syndrome develops, it is almost always a 'synucleinopathy' (Parkinson's disease, Dementia with Lewy Bodies or multiple system atrophy). Often, manifestations of parkinsonism and cognitive impairment overlap. The ability of RBD to predict disease has major implications for development of neuroprotective therapy. First, RBD is a prodromal marker with a disease risk sufficiently high for design of neuroprotective trials. Second, study of idiopathic RBD allows prospective testing of other predictive markers of neurodegeneration. Third, it allows an unprecedented direct examination of the evolution of prodromal disease into defined neurodegenerative syndromes. This review summarizes what is known about the risk of neurodegeneration in idiopathic RBD, the utility of prodromal/predictive markers in synuclein-mediated neurodegeneration, and the evolution of motor and non-motor markers in prodromal stages.

Development of the Huntington disease work function scale

OBJECTIVE

A work function measure specific for persons with prodromal Huntington disease (HD) was created to assist with workplace accommodations.

METHODS

A self-report HD Work Function (HDWF) measure was developed from focus group and expert validation.

RESULTS

Pilot studies with 238 people with prodromal HD, and 185 companions; and 89 people without prodromal HD, and 70 companions indicate that HDWF has acceptable internal consistency (Cronbach α = 0.77), acceptable interrater reliability (r = 0.58), and acceptable convergent validity with selected items from the Endicott Work Productivity Scale (r = -0.56), Social Adjustment Scale-Self Report (r = -0.29), and Everyday Cognition (r = -0.70). The HDWF can distinguish between people with prodromal HD and people with an HD family history who do not have prodromal HD (P < 0.0001).

CONCLUSIONS

The HDWF is a brief self-assessment that may be used to monitor work function.

Identifying prodromal Parkinson's disease: pre-motor disorders in Parkinson's disease

Increasing recognition that Parkinson's disease (PD) may start outside of the substantia nigra has led to a rapidly expanding effort to define prodromal stages of PD, before motor signs permit classical diagnosis. Many of these efforts center around the identification of clinical non-motor symptoms and signs of disease. There is now direct evidence that olfaction, rapid eye movement (REM) sleep behavior disorder (RBD), constipation, and depression can be present in prodromal PD. In addition, there is suggestive evidence that visual changes, other autonomic symptoms, and subtle cognitive changes may also be present at prodromal stages. A critical issue in utility of these prodromal markers will be assessment of sensitivity, specificity, and positive and negative predictive values. Although these have yet to be fully defined, olfactory deficits, some visual changes, and autonomic symptoms occur in the majority of PD patients at diagnosis, suggesting good potential sensitivity. However, with the exception of RBD and perhaps some specific autonomic measures, specificity, and positive predictive value of these markers may be insufficient to be used alone as identifiers of prodromal disease. The evidence for the utility of olfaction, RBD, autonomic markers, visual changes, mood disorders, and cognitive loss as markers of prodromal PD and the potential sensitivity and specificity of these markers are summarized.