Trial designs used to study neuroprotective therapy in Parkinson's disease

Using sustained vowels to identify patients with mild Parkinson's disease in a Chinese dataset

Introduction

Parkinson's disease (PD) is the second most common neurodegenerative disease and affects millions of people. Accurate diagnosis and subsequent treatment in the early stages can slow down disease progression. However, making an accurate diagnosis of PD at an early stage is challenging. Previous studies have revealed that even for movement disorder specialists, it was difficult to differentiate patients with PD from healthy individuals until the average modified Hoehn-Yahr staging (mH&Y) reached 1.8. Recent researches have shown that dysarthria provides good indicators for computer-assisted diagnosis of patients with PD. However, few studies have focused on diagnosing patients with PD in the early stages, specifically those with mH&Y ≤ 1.5.

Method

We used a machine learning algorithm to analyze voice features and developed diagnostic models for differentiating between healthy controls (HCs) and patients with PD, and for differentiating between HCs and patients with mild PD (mH&Y ≤ 1.5). The models were independently validated using separate datasets.

Results

Our results demonstrate that, a remarkable diagnostic performance of the model in identifying patients with mild PD (mH&Y ≤ 1.5) and HCs, with area under the ROC curve 0.93 (95% CI: 0.851.00), accuracy 0.85, sensitivity 0.95, and specificity 0.75.

Conclusion

The results of our study are helpful for screening PD in the early stages in the community and primary medical institutions where there is a lack of movement disorder specialists and special equipment.

A multimodal dataset of real world mobility activities in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder characterised by motor symptoms such as gait dysfunction and postural instability. Technological tools to continuously monitor outcomes could capture the hour-by-hour symptom fluctuations of PD. Development of such tools is hampered by the lack of labelled datasets from home settings. To this end, we propose REMAP (REal-world Mobility Activities in Parkinson's disease), a human rater-labelled dataset collected in a home-like setting. It includes people with and without PD doing sit-to-stand transitions and turns in gait. These discrete activities are captured from periods of free-living (unobserved, unstructured) and during clinical assessments. The PD participants withheld their dopaminergic medications for a time (causing increased symptoms), so their activities are labelled as being "on" or "off" medications. Accelerometry from wrist-worn wearables and skeleton pose video data is included. We present an open dataset, where the data is coarsened to reduce re-identifiability, and a controlled dataset available on application which contains more refined data. A use-case for the data to estimate sit-to-stand speed and duration is illustrated.

An International Multi-Stakeholder Delphi Survey Study on the Design of Disease Modifying Parkinson's Disease Trials

BACKGROUND

Design of disease modification (DM) trials for Parkinson's disease (PD) is challenging. Successful delivery requires a shared understanding of priorities and practicalities.

OBJECTIVE

To seek stakeholder consensus on phase 3 trials' overall goals and structure, inclusion criteria, outcome measures, and trial delivery and understand where perspectives differ.

METHODS

An international expert panel comprising people with Parkinson's (PwP), care partners (CP), clinical scientists, representatives from industry, funders and regulators participated in a survey-based Delphi study. Survey items were informed by a scoping review of DM trials and PwP input. Respondents scored item agreement over 3 rounds. Scores and reasoning were summarized by participant group each round until consensus, defined as≥70% of at least 3 participant groups falling within the same 3-point region of a 9-point Likert scale.

RESULTS

92/121 individuals from 13 countries (46/69 PwP, 13/18 CP, 20/20 clinical scientists, representatives from 8/8 companies, 4/5 funders, and 1/1 regulator) completed the study. Consensus was reached on 14/31 survey items: 5/8 overall goals and structure, 1/8 Eligibility criteria, 7/13 outcome measures, and 1/2 trial delivery items. Extent of stakeholder endorsement for 428 reasons for scores was collated across items.

CONCLUSIONS

This is the first systematic multi-stakeholder consultation generating a unique repository of perspectives on pivotal aspects of DM trial design including those of PwP and CP. The panel endorsed outcomes that holistically measure PD and the importance of inclusive trials with hybrid delivery models. Areas of disagreement will inform mitigating strategies of researchers to ensure successful delivery of future trials.

Lifestyle Interventions for the Prevention of Parkinson Disease: A Recipe for Action

The prevalence of Parkinson disease (PD) is growing fast, amplifying the quest for disease-modifying therapies in early disease phases where pathology is still limited. Lifestyle interventions offer a promising avenue for preventing progression from prodromal to manifest PD. We illustrate this primarily for 1 specific lifestyle intervention, namely aerobic exercise because the case for the other main lifestyle factor (dietary interventions) to modify the course of prodromal PD is currently less persuasive. Various observations have hinted at the disease-modifying potential of exercise. First, studies in rodents with experimental parkinsonism showed that exercise elicits adaptive neuroplasticity in basal ganglia circuitries. Second, exercise is associated with a reduced risk of developing PD, suggesting a disease-modifying potential. Third, 2 large trials in persons with manifest PD indicate that exercise can help to stabilize motor parkinsonism, although this could also reflect a symptomatic effect. In addition, exercise seems to be a feasible intervention, given its minimal risk of side effects. Theoretical risks include an increase in fall incidents and cardiovascular complications, but these concerns seem to be acceptably low. Innovative approaches using gamification elements indicate that adequate long-term compliance with regular exercise programs can be achieved, although more work remains necessary to demonstrate enduring adherence for multiple years. Advances in digital technology can be used to deliver the exercise intervention in the participant's own living environment and also to measure the outcomes remotely, which will help to further boost long-term compliance. When delivering exercise to prodromal participants, outcome measures should focus not just on phenoconversion to manifest PD (which may well take many years to occur) but also on measurable intermediate outcomes, such as physical fitness or prodromal nonmotor symptoms. Taken together, there seems to be sufficient evidence to advocate the first judicious attempt of investigating exercise as a disease-modifying treatment in prodromal PD.

Professionals’ Treatment Preferences in the Prodromal Phase of Parkinson’s Disease: A Discrete Choice Experiment

Background:

In Parkinson’s disease (PD), several disease-modifying treatments are being tested in (pre-)clinical trials. To successfully implement such treatments, it is important to have insight into factors influencing the professionals’ decision to start disease-modifying treatments in persons who are in the prodromal stage of PD.

Objective:

We aim to identify factors that professionals deem important in deciding to a start disease-modifying treatment in the prodromal stage of PD.

Methods:

We used a discrete choice experiment (DCE) to elicit preferences of neurologists and last-year neurology residents regarding treatment in the prodromal phase of PD. The DCE contained 16 hypothetical choice sets in which participants were asked to choose between two treatment options. The presented attributes included treatment effect, risk of severe side-effects, risk of mild side-effects, route of administration, and annual costs.

Results:

We included 64 neurologists and 18 last year neurology residents. Participants attached most importance to treatment effect and to the risk of severe side-effects. Participants indicated that they would discuss one of the presented treatments in daily practice more often in persons with a high risk of being in the prodromal phase compared to those with a moderate risk. Other important factors for deciding to start treatment included the amount of evidence supporting the putative treatment effect, the preferences of the person in the prodromal phase, and the life expectancy.

Conclusion:

This study provides important insights in factors that influence decision making by professionals about starting treatment in the prodromal phase of PD.

Mitigated Oxidative Stress and Cognitive Impairments in Transient Global Ischemia using Niosomal Selegiline-NBP delivery

Stroke is the most common reason for adult disabilities and the second ground for death worldwide. Our previous study revealed that selegiline serves as an alternative candidate in transient hypoxia-ischemia. However, aggressive and restless behavior was observed in stroke-induced rats receiving 4 mg/kg selegiline. In comparison, 1 mg/kg selegiline could induce negligible therapeutic effects on mitochondrial dysfunction and histopathological changes. Therefore, we designed oral noisome-based selegiline attached to 4-(4-nitrobenzyl) pyridine to improve transient global ischemia by attenuating cognitive impairments, oxidative stress, and histopathological injury. The investigation was performed in transient hypoxia-ischemia-induced rats by oral administration of nanoformulation containing selegiline (0.25-1 mg/kg) for 4 weeks (3 times a week). Novel object recognition (NOR) was considered to evaluate their cognitive dysfunction. Oxidative stress parameters and brain histopathological assessments were determined following the scarification of rats. Outstandingly, our data demonstrated slower selegiline release from niosomes relative to free drug, which was also in a controlled manner. Our data confirmed significant improvement in cognitive behavior in the NOR test, an increase in glutathione level and total antioxidant power, a decline in MDA and protein carbonyl level, as well as a decreased number of dead cells in histopathological assessment after being exposed to (0.5-1 mg/kg) selegiline-NBP nanoformulation. These data manifested that the selegiline-NBP nanoformulation (0.5-1 mg/kg) could significantly reduce oxidative damage, cognitive dysfunction, and histopathological damage compared to transient hypoxia-ischemia rats, which is 20 times lower than the therapeutic dose in humans. Therefore, the proposed nanoformulation would be capable as an alternative candidate without side effects in stroke.

Acceptability of an In-Home Multimodal Sensor Platform in Parkinson’s Disease: A Qualitative Study (Preprint)

Background

Parkinson disease (PD) symptoms are complex, gradually progressive, and fluctuate hour by hour. Home-based technological sensors are being investigated to measure symptoms and track disease progression. A smart home sensor platform, with cameras and wearable devices, could be a useful tool to use to get a fuller picture of what someone’s symptoms are like. High-resolution video can capture the ground truth of symptoms and activities. There is a paucity of information about the acceptability of such sensors in PD.

Objective

The primary objective of our study was to explore the acceptability of living with a multimodal sensor platform in a naturalistic setting in PD. Two subobjectives are to identify any suggested limitations and to explore the sensors’ impact on participant behaviors.

Methods

A qualitative study was conducted with an inductive approach using semistructured interviews with a cohort of PD and control participants who lived freely for several days in a home-like environment while continuously being sensed.

Results

This study of 24 participants (12 with PD) found that it is broadly acceptable to use multimodal sensors including wrist-worn wearables, cameras, and other ambient sensors passively in free-living in PD. The sensor that was found to be the least acceptable was the wearable device. Suggested limitations on the platform for home deployment included camera-free time and space. Behavior changes were noted by the study participants, which may have related to being passively sensed. Recording high-resolution video in the home setting for limited periods of time was felt to be acceptable to all participants.

Conclusions

The results broaden the knowledge of what types of sensors are acceptable for use in research in PD and what potential limitations on these sensors should be considered in future work. The participants’ reported behavior change in this study should inform future similar research design to take this factor into account. Collaborative research study design, involving people living with PD at every stage, is important to ensure that the technology is acceptable and that the data outcomes produced are ecologically valid and accurate.

International Registered Report Identifier (IRRID)

RR2-10.1136/bmjopen-2020-041303

Protocol for PD SENSORS: Parkinson's Disease Symptom Evaluation in a Naturalistic Setting producing Outcome measuRes using SPHERE technology. An observational feasibility study of multi-modal multi-sensor technology to measure symptoms and activities of daily living in Parkinson's disease

INTRODUCTION

The impact of disease-modifying agents on disease progression in Parkinson's disease is largely assessed in clinical trials using clinical rating scales. These scales have drawbacks in terms of their ability to capture the fluctuating nature of symptoms while living in a naturalistic environment. The SPHERE (Sensor Platform for HEalthcare in a Residential Environment) project has designed a multi-sensor platform with multimodal devices designed to allow continuous, relatively inexpensive, unobtrusive sensing of motor, non-motor and activities of daily living metrics in a home or a home-like environment. The aim of this study is to evaluate how the SPHERE technology can measure aspects of Parkinson's disease.

METHODS AND ANALYSIS

This is a small-scale feasibility and acceptability study during which 12 pairs of participants (comprising a person with Parkinson's and a healthy control participant) will stay and live freely for 5 days in a home-like environment embedded with SPHERE technology including environmental, appliance monitoring, wrist-worn accelerometry and camera sensors. These data will be collected alongside clinical rating scales, participant diary entries and expert clinician annotations of colour video images. Machine learning will be used to look for a signal to discriminate between Parkinson's disease and control, and between Parkinson's disease symptoms 'on' and 'off' medications. Additional outcome measures including bradykinesia, activity level, sleep parameters and some activities of daily living will be explored. Acceptability of the technology will be evaluated qualitatively using semi-structured interviews.

ETHICS AND DISSEMINATION

Ethical approval has been given to commence this study; the results will be disseminated as widely as appropriate.

Approaches to Disease Modification for Parkinson's Disease: Clinical Trials and Lessons Learned

Despite many clinical trials over the last three decades, the goal of demonstrating that a treatment slows the progression of Parkinson's disease (PD) remains elusive. Research advances have shed new insight into cellular pathways contributing to PD pathogenesis and offer increasingly compelling therapeutic targets. Here we review recent and ongoing clinical trials employing novel strategies toward disease modification, including those targeting alpha-synuclein and those repurposing drugs approved for other indications. Active and passive immunotherapy approaches are being studied with the goal to modify the spread of alpha-synuclein pathology in the brain. Classes of currently available drugs that have been proposed to have potential disease-modifying effects for PD include calcium channel blockers, antioxidants, anti-inflammatory agents, iron-chelating agents, glucagon-like peptide 1 agonists, and cAbl tyrosine kinase inhibitors. The mechanistic diversity of these treatments offers hope, but to date, results from these trials have been disappointing. Nevertheless, they provide useful lessons in guiding future therapeutic development.

Clinical trials in REM sleep behavioural disorder: challenges and opportunities

The rapid eye movement sleep behavioural disorder (RBD) population is an ideal study population for testing disease-modifying treatments for synucleinopathies, since RBD represents an early prodromal stage of synucleinopathy when neuropathology may be more responsive to treatment. While clonazepam and melatonin are most commonly used as symptomatic treatments for RBD, clinical trials of symptomatic treatments are also needed to identify evidence-based treatments. A comprehensive framework for both disease-modifying and symptomatic treatment trials in RBD is described, including potential treatments in the pipeline, cost-effective participant recruitment and selection, study design, outcomes and dissemination of results. For disease-modifying treatment clinical trials, the recommended primary outcome is phenoconversion to an overt synucleinopathy, and stratification features should be used to select a study population at high risk of phenoconversion, to enable more rapid clinical trials. For symptomatic treatment clinical trials, objective polysomnogram-based measurement of RBD-related movements and vocalisations should be the primary outcome measure, rather than subjective scales or diaries. Mobile technology to enable objective measurement of RBD episodes in the ambulatory setting, and advances in imaging, biofluid, tissue, and neurophysiological biomarkers of synucleinopathies, will enable more efficient clinical trials but are still in development. Increasing awareness of RBD among the general public and medical community coupled with timely diagnosis of these diseases will facilitate progress in the development of therapeutics for RBD and associated neurodegenerative disorders.

Ferulic Acid Ameliorates MPP+/MPTP-Induced Oxidative Stress via ERK1/2-Dependent Nrf2 Activation: Translational Implications for Parkinson Disease Treatment

Parkinson's disease (PD) is a neurodegenerative disorder closely associated with oxidative stress. The biochemical and cellular alterations that occur after cell and mouse treatment with the parkinsonism-inducing neurotoxin MPP⁺/MPTP are remarkably similar to those observed in idiopathic PD. Previously, we showed that ferulic acid (FA) has antioxidant properties and the ability to activate nuclear factor E2-related factor 2 (Nrf2). The present study tested the hypothesis that FA attenuates MPP⁺/MPTP-induced oxidative stress by regulating crosstalk between sirtuin 2 (SIRT2) and Nrf2 pathways. To test this hypothesis, we performed in vitro and in vivo studies using MPP⁺/MPTP-challenged SH-SY5Y cells or mice treated with or not with FA. FA marginally inhibited SIRT2 in parallel with α-synuclein at levels of transcription and translation in SH-SY5Y cells challenged with MPP⁺. Moreover, FA attenuated MPP⁺-induced oxidative stress, as indicated by reactive oxygen species, lipid hydroperoxides, GSH/GSSG ratio, and NAD⁺/NADH ratio. Mechanistically, FA strongly upregulated the glutamate cysteine ligase catalytic subunit and heme oxygenase-1 expression at the levels of transcription and translation. Interestingly, FA-mediated extracellular signal-regulated kinases 1 and 2 (ERK1/2) activation contributed to nuclear accumulation of Nrf2 via de novo synthesis, which was validated by the use of dominant negative ERK2. Surprisingly, activation of the ERK1/2 and inhibition of SIRT2 by FA are mediated by independent mechanisms. Furthermore, FA ameliorated motor deficits and oxidative stress in the ventral midbrain in MPTP-treated (25 mg/kg, i.p., daily for 5 days) wild-type mice and α-synuclein knockout mice, but not in Nrf2 knockout mice. Collectively, FA exerts antioxidant effects through ERK1/2-mediated activation of the Nrf2 pathway, and these results may have important translational value for the treatment of PD.

Initiation of pharmacological therapy in Parkinson's disease: when, why, and how

Debate is ongoing regarding when, why, and how to initiate pharmacotherapy for Parkinson's disease. Early initiation of dopaminergic therapies does not convey disease-modifying effects but does reduce disability. Concerns about the development of motor complications arising from the early initiation of levodopa, which led to misconceived levodopa-sparing strategies, have been largely mitigated by the outcomes of the PD MED and Levodopa in Early Parkinson's Disease (LEAP) studies. The LEAP study also showed the potential for early improvement in quality of life, even when disability is negligible. Until more effective methods of providing stable dopamine concentrations are developed, current evidence supports the use of levodopa as initial symptomatic treatment in most patients with Parkinson's disease, starting with low doses and titrating to therapeutic threshold. Monoamine oxidase-B inhibitors and dopamine agonists can be reserved as potential adjunct treatments later in the disease course. Future research will need to establish effective disease-modifying treatments, address whether patients' quality of life is substantially improved with early initiation of treatment rather than a wait and watch strategy, and establish whether new levodopa formulations will delay onset of dyskinesia.

Correlations between dopaminergic dysfunction and abnormal metabolic network activity in REM sleep behavior disorder

Striatal dopamine transporter (DAT) deficiency and abnormal expression of Parkinson's disease (PD)-related pattern (PDRP) have been observed in patients with idiopathic REM sleep behavior disorder (IRBD). This study aimed to investigate the correlations between these two measures with comparison to PD using a dual tracer imaging design. Age-matched 37 IRBD patients, 86 PD patients, and 15 control subjects underwent concurrent PET scans with 11C-CFT to quantify dopaminergic dysfunction and 18F-FDG to quantify PDRP expression. IRBD patients were divided into two subgroups: those with relatively normal (IRBD-RN) or abnormal (IRBD-AB) striatal DAT binding. Significantly decreased DAT binding and increased PDRP scores were present in all patient groups, except for IRBD-RN, relative to the controls. There was a significant effect of hemisphere and hemisphere × group interaction for DAT binding but not for PDRP expression. Significant correlations were observed between DAT binding and PDRP expression in the IRBD-AB and PD groups but not in the IRBD-RN group. IRBD patients present with an intermediate state in striatal DAT distribution and PDRP activity between PD and normal controls. The modest correlations between the two measures in both IRBD and PD suggest that differences in network activity cannot be fully explained by nigrostriatal dopaminergic denervation.

Systematic Review Looking at the Use of Technology to Measure Free-Living Symptom and Activity Outcomes in Parkinson's Disease in the Home or a Home-like Environment

BACKGROUND

The emergence of new technologies measuring outcomes in Parkinson's disease (PD) to complement the existing clinical rating scales has introduced the possibility of measurement occurring in patients' own homes whilst they freely live and carry out normal day-to-day activities.

OBJECTIVE

This systematic review seeks to provide an overview of what technology is being used to test which outcomes in PD from free-living participant activity in the setting of the home environment. Additionally, this review seeks to form an impression of the nature of validation and clinimetric testing carried out on the technological device(s) being used.

METHODS

Five databases (Medline, Embase, PsycInfo, Cochrane and Web of Science) were systematically searched for papers dating from 2000. Study eligibility criteria included: adults with a PD diagnosis; the use of technology; the setting of a home or home-like environment; outcomes measuring any motor and non-motor aspect relevant to PD, as well as activities of daily living; unrestricted/unscripted activities undertaken by participants.

RESULTS

65 studies were selected for data extraction. There were wide varieties of participant sample sizes (<10 up to hundreds) and study durations (<2 weeks up to a year). The metrics evaluated by technology, largely using inertial measurement units in wearable devices, included gait, tremor, physical activity, bradykinesia, dyskinesia and motor fluctuations, posture, falls, typing, sleep and activities of daily living.

CONCLUSIONS

Home-based free-living testing in PD is being conducted by multiple groups with diverse approaches, focussing mainly on motor symptoms and sleep.

Effects of Combined Treatment with Acupuncture and Chunggan Formula in a Mouse Model of Parkinson's Disease

Parkinson's disease is the second most common neurodegenerative disease. Patients with Parkinson's disease can be treated with a combination of acupuncture and herbal medicine, but studies on the synergistic effects of the combined treatment have not yet been conducted. Thus, we subjected an MPTP-induced Parkinson's disease mouse model to the combined treatment. We used acupoint GB34 for acupuncture and modified Chunggantang (KD5040) as the herbal medicine, as they have been reported to be effective in Parkinson's disease. We investigated the suboptimal dose of KD5040 and then used this dose in the combined treatment. The results showed that the combined treatment had a synergistic effect on improvements in abnormal motor function and neurodegeneration compared with the use of acupuncture or herbal medicine alone. The combined treatment also had a neuroprotective effect via the PI3K/AKT and MAPK/ERK signaling pathways. These findings suggest that the combined treatment with acupuncture and KD5040 can help improve the symptoms of Parkinson's disease.

Simvastatin as a neuroprotective treatment for Parkinson's disease (PD STAT): protocol for a double-blind, randomised, placebo-controlled futility study

INTRODUCTION

Parkinson's disease (PD) is a progressive neurodegenerative condition affecting approximately 185,000 people in the UK. No drug has been proven to slow disease progression. Epidemiological and pre-clinical data support simvastatin, a widely used cholesterol-lowering drug with a well-established safety profile, having neuroprotective properties. The aim of this study (Simvastatin as a neuroprotective treatment for PD (PD STAT)) is to determine whether simvastatin has the potential to slow PD progression. The study is part of the International Linked Clinical Trials initiative coordinated by The Cure Parkinson's Trust. This paper describes the protocol for the PD STAT study.

METHODS AND ANALYSIS

PD STAT is a double-blind, randomised, placebo-controlled, multi-centre, parallel group, futility trial in patients with PD of mild-moderate severity. 235 participants have been recruited and randomly allocated in a 1:1 ratio to receive either oral simvastatin or matched placebo. Treatment involves a 1-month low-dose phase (40 mg daily), followed by a 23-month high-dose phase (80 mg daily) and ends with a 2-month washout period. Participants are reviewed at clinic visits at 1 month, 6, 12, 18, 24 and 26 months post-baseline, with interim telephone follow-up to monitor for adverse events.The primary outcome is the change in the Movement Disorder Society Unified Parkinson's Disease Rating Scale part III motor subscale score in the practically defined OFF medication state (OFF state) between baseline and 24 months. Primary analysis will be on a modified intention to treat basis and will include only those participants who progress to the high-dose phase of the study.

ETHICS AND DISSEMINATION

The protocol has been approved by the North East-Newcastle and North Tyneside 2 Research Ethics Committee. The results will be disseminated via research articles in peer-reviewed journals and presentations at local, national and international scientific meetings, as well as disseminated via patient groups, websites and networks. A summary of the study findings will be posted to participants at the end of the study.

TRIAL REGISTRATION

ISRCTN16108482 (prospectively registered); EudraCT 2015-000148-40; ClinicalTrials.gov NCT02787590; Pre-results.

22q11.2 Deletion Syndrome-Associated Parkinson's Disease

BACKGROUND

22q11.2 deletion syndrome (22q11.2DS) is a multisystem condition associated with an increased risk of early-onset Parkinson's disease (PD).

METHODS

We review the clinical, neuroimaging, and neuropathological observations, as well as diagnostic challenges, of PD in 22q11.2DS. We conducted a search of PubMed up until June 1, 2018 and personal files to identify relevant publications.

RESULTS

22q11.2DS-associated PD is responsible for approximately 0.5% of early-onset PD. The hallmark motor symptoms and neuropathology of PD, and typical findings of reduced striatal dopamine transporter binding with molecular imaging, are present in 22q11.2DS-associated PD. Mean age at PD onset in 22q11.2DS is relatively young (∼40 years). Patients with 22q11.2DS-associated PD show a good response to levodopa.

CONCLUSIONS

Further recognition of 22q11.2DS and study of PD in people with 22q11.2DS could provide insights into the mechanisms that cause PD in the general population. 22q11.2DS may serve as an identifiable PD model to study prodromal PD and disease-modifying treatments.

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

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

Combination Treatment of Icariin and L-DOPA Against 6-OHDA-Lesioned Dopamine Neurotoxicity

Until now, the dopamine (DA) precursor, L-3,4-dihydroxyphenylalanine (L-DOPA), remains the gold standard effective drug therapy for Parkinson’s disease (PD) patients. Nevertheless, long-term chronic L-DOPA administration leads to the drug efficacy loss and severe adverse effects, such as L-DOPA-induced dyskinesia (LID). Icariin (ICA), a flavonoid that is extracted from Epimedium, has been proved to evoke neuroprotection against DA neuronal loss in PD animal models. Here, the present study detected the effects of ICA combined with L-DOPA on 6-hydroxydopamine (6-OHDA)-elicited DA neurotoxicity and L-DOPA-induced motor dysfunction as well. PC12 cells were applied to investigate the combination treatment of ICA and L-DOPA against 6-OHDA-lesioned neurotoxicity. In addition, rat substantia nigral stereotaxic injection of 6-OHDA-induced DA neuronal injury was performed to explore the neuroprotective effects mediated by ICA combined with L-DOPA. The pathological movement triggered by L-DOPA was determined by the abnormal involuntary movements (AIM) scores analysis. In PC12 cells, ICA combined with L-DOPA produced better neuroprotection from 6-OHDA-induced neurotoxicity than ICA or L-DOPA alone treatment. In parkinsonian 6-OHDA lesioned rats, ICA conferred DA neuroprotection as monotherapy and an enhancement benefit of L-DOPA treatment after daily administration of L-DOPA and ICA for 21 days. Moreover, ICA ameliorated the development of LID as evidenced by the lowered AIM scores without affecting L-DOPA-mediated efficacy. Furtherly, ICA attenuated neuroinflammation in 6-OHDA-induced DA neuronal loss and the development of LID in vivo. In conclusion, these findings suggest ICA might be a potential promising adjuvant to enhance L-DOPA efficacy and attenuate L-DOPA-produced adverse effects in PD.

Diagnosing Parkinson Disease

PURPOSE OF REVIEW

While establishing the diagnosis of Parkinson disease (PD) can be straightforward, it can be challenging in some patients, even for the experienced neurologist. The misdiagnosis rate ranges from 10% to 20% or greater depending on clinician experience.

RECENT FINDINGS

Despite promise in the search for a biomarker that can establish the presence of PD and act as a marker of its progression, the diagnosis of PD continues to be based on clinical examination. Core criteria, exclusion criteria, and supportive criteria have been developed to aid the clinician in establishing the diagnosis. Nonmotor symptoms of PD are usually present at the time of diagnosis, may precede motor symptoms, and should be specifically sought during evaluation. Ancillary testing can be appropriate, but its indications and utility must be clearly understood.

SUMMARY

The diagnosis of PD requires the recognition of the core features of PD and the differentiation of its clinical presentation from other entities with similar and potentially overlapping symptoms. A careful history and examination guided by clinical diagnostic criteria will usually establish the diagnosis of PD or uncover red flags for the possibilities of other diagnoses. Appropriate selection and interpretation of ancillary testing is critical to avoid misdiagnosis and unnecessary tests.

Renin-angiotensin system as a potential target for new therapeutic approaches in Parkinson's disease

INTRODUCTION

Currently, available therapies for Parkinson's disease (PD) are symptomatic. Therefore, the search for neuroprotective drugs remains a top priority. Areas covered: In this review, the potential symptomatic or disease-modifying effect of drugs targeting the Renin-Angiotensin System (RAS) in PD will be explored. Expert opinion: The importance of nigrostriatal local RAS has only begun to be unraveled in the last decades. On one hand, there is a complex feedback cycle between RAS and dopamine (DA). On the other hand, RAS affects dopaminergic neurons vulnerability. Neuroprotective effects in animal PD models have been shown for the angiotensin-converting enzyme (ACE) inhibitors captopril and perindopril, and the AT1 receptor antagonists losartan, candesartan and telmisartan. These effects appear to be mediated by a reduction in the overproduction of reactive oxygen species. In a proof-of-concept, randomized, double-blind, crossover study in PD patients, perindopril enhanced the effect of levodopa without inducing dyskinesias. There has not been any clinical trial exploring the neuroprotective effect of RAS drugs, but one cohort study in hypertensive patients suggested a protective effect of ACE inhibitors on PD risk. RAS is a promising target for symptomatic and neuroprotective therapies in PD. Further studies in PD animal models and patients are warranted.

Effects of a combination treatment of KD5040 and L-dopa in a mouse model of Parkinson's disease

Background

Although the dopamine precursor L-3, 4-dihydroxyphenylalanine (_l-dopa) remains the gold standard pharmacological therapy for patients with Parkinson’s disease (PD), long-term treatment with this drug has been known to result in several adverse effects, including _l-dopa-induced dyskinesia (LID). Recently, our group reported that KD5040, a modified herbal remedy, had neuroprotective effects in both in vitro and in vivo models of PD. Thus, the present study investigated whether KD5040 would have synergistic effects with _l-dopa and antidyskinetic effects caused by _l-dopa as well.

Methods

The effects of KD5040 and _l-dopa on motor function, expression levels of substance P (SP) and enkephalin (ENK) in the basal ganglia, and glutamate content in the motor cortex were assessed using behavioral assays, immunohistochemistry, Western blot analyses, and liquid chromatography tandem mass spectrometry in a mouse model of PD induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). In addition, the antidyskinetic effects of KD5040 on pathological movements triggered by _l-dopa were investigated by testing abnormal involuntary movements (AIMs) and measuring the activations of FosB, cAMP-dependent phosphor protein of 32 kDa (DARPP-32), extracellular signal-regulated kinases (ERK), and cAMP response element-binding (CREB) protein in the striatum.

Results

KD5040 synergistically improved the motor function when low-dose _l-dopa (LL) was co-administered. In addition, it significantly reversed MPTP-induced lowering of SP, improved ENK levels in the basal ganglia, and ameliorated abnormal reduction in glutamate content in the motor cortex. Furthermore, KD5040 significantly lowered AIMs and controlled abnormal levels of striatal FosB, pDARPP-32, pERK, and pCREB induced by high-dose _l-dopa.

Conclusions

KD5040 lowered the effective dose of _l-dopa and alleviated LID. These findings suggest that KD5040 may be used as an adjunct therapy to enhance the efficacy of _l-dopa and alleviate its adverse effects in patients with PD.

Disease-Modifying Drugs in Parkinson's Disease

Despite an increased understanding of the pathogenesis of Parkinson's disease (PD), and a number of drugs designed to ameliorate symptoms, finding an effective neuroprotective therapy remains elusive. For decades now, several promising agents targeting different pathways have been explored as potential treatments that could help slow disease progression, but these have met with limited success. There are hurdles to overcome, particularly given that there is no exact animal model of PD and also no reliable biomarkers for PD. Without biomarkers, it is not possible to demonstrate, in the context of a clinical trial, that an intervention prevents neuronal degeneration. However, given the compelling scientific rationale of several compounds, an unrelenting pursuit continues. There have been hundreds of human studies looking at neuroprotection in PD. This article will briefly summarize several of the neuroprotective treatments that have been evaluated in large clinical trials, and will also outline some of the newer therapies that are currently being explored.

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

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

How close are we to individualized medicine for Parkinson's disease?

INTRODUCTION

There is a considerable inter-individual heterogeneity in clinical features, disease course, and treatment response in Parkinson's disease (PD), which can be explained not only by disease process and clinical variables, but also by an impact from genetic factors. Evidence-based medicine relies on large randomized control trials and meta-analysis-average medicine, which ignores individual differences. However, we are now in the early phases of a paradigm shift in medicine relating to individuality and variability. The purpose of individualized medicine is to predict patients' responses to targeted therapy using diagnostic tests based on genetics or other molecular mechanisms, thus providing the right drug at the right dose at the right time.

AREAS COVERED

In this article, we outline current state of individualized medicine for PD. Expert Commentary: Pharmacogenomics, an important element of individualized medicine, is just beginning to be considered in PD. To advance the clinical use of pharmacogenomics, big data cohort for genomic research and multidisciplinary team approaches are necessary.

[Development of preclinical diagnosis and preventive treatment of neurodegenerative diseases]

Neurodegenerative diseases (NDD) are serious fatal neurological and mental diseases that resulted in disability and fethal outcome. Based on the advances of basic sciences over the last two decades, new knowledge on the risk factors for NDD and molecular mechanisms of the pathogenesis are obtained. It has been shown that the accelerated process of neuronal death which is the main cause of NDD development begins long before the appearance of clinical symptoms. The first symptoms appeared only after the death of most specific regulatory neurons and exhaustion of brain compensatory reserve. Only at that time, one can make the diagnosis and start traditional treatment of patients that accounts for the extremely low efficacy of the latter. Currently, complex preclinical diagnosis based on the identification of relatively specific clinical precursors and peripheral biomarkers has been developing. Development of preclinical diagnosis and preventive treatment is a strategic issue of modern neurology and psychiatry. The resolution of this issue allows to consider NDD as cured, but not fatal, diseases.

Predicting Parkinson disease in the community using a nonmotor risk score

At present, there are no validated methods to identify persons who are at increased risk for Parkinson Disease (PD) from the general population. We investigated the clinical usefulness of a recently proposed non-motor risk score for PD (the PREDICT-PD risk score) in the population-based Rotterdam Study. At baseline (1990), we constructed a weighted risk score based on 10 early nonmotor features and risk factors in 6492 persons free of parkinsonism and dementia. We followed these persons for up to 20 years (median 16.1 years) for the onset of PD until 2011. We studied the association between the PREDICT-PD risk score and incident PD using competing risk regression models with adjustment for age and sex. In addition, we assessed whether the PREDICT-PD risk score improved discrimination (C-statistics) and risk classification (net reclassification improvement) of incident PD beyond age and sex. During follow-up, 110 persons were diagnosed with incident PD. The PREDICT-PD risk score was associated with incident PD (hazard ratio [HR] = 1.30; 95 % confidence interval [1.06; 1.59]) and yielded a small, non-significant improvement in overall discrimination (ΔC-statistic = 0.018[-0.005; 0.041]) and risk classification (net reclassification improvement = 0.172[-0.017; 0.360]) of incident PD. In conclusion, the PREDICT-PD risk score only slightly improves long-term prediction of PD in the community.

[Right ventricular dilatation in patients with coronary heart disease without myocardial infarction: According to the data of the Coronary Angiography Surgery Registry]

AIM

To identify factors associated with right ventricular (RV) dilatation in patients with coronary heart disease (CHD) without prior myocardial infarction (Ml).

SUBJECTS AND METHODS

Out of 16 839 patents from the Coronary Angiography Surgery Registry, the investigators selected patients with >75% stenosis in at least one coronary artery without acute or prior MI: 75 patients with echocardiographically detected RV dilatation and 1134 without RV dilatation.

RESULTS

Among the patients with RV dilatation, there were more men (92% versus 80.2%; p=0.01 2). In this group, the mean body mass index (BMI) was higher (31.7±5.2 kg/m2 versus 30.1±4.7 kg/m2; p=0.01 9); there was more commonly higher NYHA functional class (FC) (III) chronic heart failure (CHF) (22.2% versus 12.5%; p=0.002), clinically relevant mitral regurgitation (29.4% versus 4.0%; all ps<0.001), and cardiac rhythm and conduction disturbances (45.5% versus 17.8%; p<0.001) in rarer severe FC (III-IV) exertional angina (30.3% versus 52.8%; p=0.007). The groups were different as evidenced by coronarography and major blood biochemical indicators. Decreased myocardial contractility (odds ratio (OR), 4.22; p=0.002), male sex (OR, 4.03;p=0.007), cardiac rhythm and conduction disturbances (OR, 2.98; p<0.001), clinically relevant mitral regurgitation (OR, 2.34; p=0.001); higher FC CHF (OR, 1.87; p=0.034), BMI (OR, 1.08; p=0.01 0), and lower FC exertional angina (OR, 0.42; p=0.001) demonstrated an independent relationship to RV dilatation, as evidenced by a multivariateanalysis.

CONCLUSION

In the patients with CHD without MI, RV dilatation is independently related to male sex, left ventricular functional characteristics, and higher BMI.

Nonpharmacological treatments for patients with Parkinson's disease

Since 2013, a number of studies have enhanced the literature and have guided clinicians on viable treatment interventions outside of pharmacotherapy and surgery. Thirty-three randomized controlled trials and one large observational study on exercise and physiotherapy were published in this period. Four randomized controlled trials focused on dance interventions, eight on treatment of cognition and behavior, two on occupational therapy, and two on speech and language therapy (the latter two specifically addressed dysphagia). Three randomized controlled trials focused on multidisciplinary care models, one study on telemedicine, and four studies on alternative interventions, including music therapy and mindfulness. These studies attest to the marked interest in these therapeutic approaches and the increasing evidence base that places nonpharmacological treatments firmly within the integrated repertoire of treatment options in Parkinson's disease.

Pioglitazone in early Parkinson's disease: a phase 2, multicentre, double-blind, randomised trial

BACKGROUND

A systematic assessment of potential disease-modifying compounds for Parkinson's disease concluded that pioglitazone could hold promise for the treatment of patients with this disease. We assessed the effect of pioglitazone on the progression of Parkinson's disease in a multicentre, double-blind, placebo-controlled, futility clinical trial.

METHODS

Participants with the diagnosis of early Parkinson's disease on a stable regimen of 1 mg/day rasagiline or 10 mg/day selegiline were randomly assigned (1:1:1) to 15 mg/day pioglitazone, 45 mg/day pioglitazone, or placebo. Investigators were masked to the treatment assignment. Only the statistical centre and the central pharmacy knew the treatment name associated with the randomisation number. The primary outcome was the change in the total Unified Parkinson's Disease Rating Scale (UPDRS) score between the baseline and 44 weeks, analysed by intention to treat. The primary null hypothesis for each dose group was that the mean change in UPDRS was 3 points less than the mean change in the placebo group. The alternative hypothesis (of futility) was that pioglitazone is not meaningfully different from placebo. We rejected the null if there was significant evidence of futility at the one-sided alpha level of 0·10. The study is registered at ClinicalTrials.gov, number NCT01280123.

FINDINGS

210 patients from 35 sites in the USA were enrolled between May 10, 2011, and July 31, 2013. The primary analysis included 72 patients in the 15 mg group, 67 in the 45 mg group, and 71 in the placebo group. The mean total UPDRS change at 44 weeks was 4·42 (95% CI 2·55-6·28) for 15 mg pioglitazone, 5·13 (95% CI 3·17-7·08) for 45 mg pioglitazone, and 6·25 (95% CI 4·35-8·15) for placebo (higher change scores are worse). The mean difference between the 15 mg and placebo groups was -1·83 (80% CI -3·56 to -0·10) and the null hypothesis could not be rejected (p=0·19). The mean difference between the 45 mg and placebo groups was -1·12 (80% CI -2·93 to 0·69) and the null hypothesis was rejected in favour of futility (p=0·09). Planned sensitivity analyses of the primary outcome, using last value carried forward (LVCF) to handle missing data and using the completers' only sample, suggested that the 15 mg dose is also futile (p=0·09 for LVCF, p=0·09 for completers) but failed to reject the null hypothesis for the 45 mg dose (p=0·12 for LVCF, p=0·19 for completers). Six serious adverse events occurred in the 15 mg group, nine in the 45 mg group, and three in the placebo group; none were thought to be definitely or probably related to the study interventions.

INTERPRETATION

These findings suggest that pioglitazone at the doses studied here is unlikely to modify progression in early Parkinson's disease. Further study of pioglitazone in a larger trial in patients with Parkinson's disease is not recommended.

FUNDING

National Institute of Neurological Disorders and Stroke.

Biomarkers of Parkinson's disease: present and future

Sporadic or idiopathic Parkinson's disease (PD) is an age-related neurodegenerative disorder of unknown origin that ranks only second behind Alzheimer's disease (AD) in prevalence and its consequent social and economic burden. PD neuropathology is characterized by a selective loss of dopaminergic neurons in the substantia nigra pars compacta; however, more widespread involvement of other CNS structures and peripheral tissues now is widely documented. The onset of molecular and cellular neuropathology of PD likely occurs decades before the onset of the motor symptoms characteristic of PD. The hallmark symptoms of PD, resting tremors, rigidity and postural disabilities, are related to dopamine (DA) deficiency. Current therapies treat these symptoms by replacing or boosting existing DA. All current interventions have limited therapeutic benefit for disease progression because damage likely has progressed over an estimated period of ~5 to 15years to a loss of 60%-80% of the nigral DA neurons, before symptoms emerge. There is no accepted definitive biomarker of PD. An urgent need exists to develop early diagnostic biomarkers for two reasons: (1) to intervene at the onset of disease and (2) to monitor the progress of therapeutic interventions that may slow or stop the course of the disease. In the context of disease development, one of the promises of personalized medicine is the ability to predict, on an individual basis, factors contributing to the susceptibility for the development of a given disease. Recent advances in our understanding of genetic factors underlying or contributing to PD offer the potential for monitoring susceptibility biomarkers that can be used to identify at-risk individuals and possibly prevent the onset of disease through treatment. Finally, the exposome concept is new in the biomarker discovery arena and it is suggested as a way to move forward in identifying biomarkers of neurological diseases. It is a two-stage scheme involving a first stage of exposome-wide association studies (EWAS) to profile omic features in serum to discover molecular biomarkers. The second stage involves application of this knowledge base in follow-up studies. This strategy is unique in that it promotes the use of data-driven (omic) strategies in interrogating diseased and healthy populations and encourages a movement away from using only reductionist strategies to discover biomarkers of exposure and disease. In this short review we will examine 1) advances in our understanding of the molecular mechanisms underlying PD that have led to candidate biomarkers for diagnosis and treatment efficacy and 2) new technologies on the horizon that will lead to novel approaches in biomarker development.

Prediagnostic presentations of Parkinson's disease in primary care: a case-control study

BACKGROUND

Parkinson's disease has an insidious onset and is diagnosed when typical motor features occur. Several motor and non-motor features can occur before diagnosis, early in the disease process. We aimed to assess the association between first presentation of several prediagnostic features in primary care and a subsequent diagnosis of Parkinson's disease, and to chart the timeline of these first presentations before diagnosis.

METHODS

We identified individuals with a first diagnosis of Parkinson's disease and those without Parkinson's disease from Jan 1, 1996, to Dec 31, 2012, from The Health Improvement Network UK primary care database. Codes were extracted for a range of possible prediagnostic or early symptoms, comprising motor features (tremor, rigidity, balance impairments, neck pain or stiffness, and shoulder pain or stiffness), autonomic features (constipation, hypotension, erectile dysfunction, urinary dysfunction, and dizziness), neuropsychiatric disturbances (memory problems, late-onset anxiety or depression, cognitive decline, and apathy), and additional features (fatigue, insomnia, anosmia, hypersalivation and rapid-eye-movement sleep behaviour disorder) in the years before diagnosis. We report the incidence of symptoms recorded in more than 1% of cases per 1000 person-years and incidence risk ratios (RRs) for individuals with and without Parkinson's disease at 2, 5, and 10 years before diagnosis.

FINDINGS

8166 individuals with and 46,755 individuals without Parkinson's disease were included in the study. Apathy, REM sleep behaviour disorder, anosmia, hypersalivation, and cognitive decline were all reported in less than 1% of people per 1000 person-years and were excluded from further analyses. At 2 years before Parkinson's disease diagnosis, the incidence of all studied prediagnostic features except neck pain or stiffness was higher in patients who went on to develop Parkinson's disease (n=7232) than in controls (n=40,541). At 5 years before diagnosis, compared with controls (n=25,544), patients who went on to develop Parkinson's disease (n=4769) had a higher incidence of tremor (RR 13·70, 95% CI 7·82-24·31), balance impairments (2·19, 1·09-4·16), constipation (2·24, 2·04-2·46), hypotension (3·23, 1·85-5·52), erectile dysfunction (1·30, 1·11-1·51), urinary dysfunction (1·96, 1·34-2·80), dizziness (1·99, 1·67-2·37), fatigue (1·56, 1·27-1·91), depression (1·76, 1·41-2·17), and anxiety (1·41, 1·09-1·79). At 10 years before diagnosis of Parkinson's disease, the incidence of tremor (RR 7·59, 95% CI 1·11-44·83) and constipation (2·01, 1·62-2·49) was higher in those who went on to develop Parkinson's disease (n=1680) than in controls (n=8305).

INTERPRETATION

A range of prediagnostic features can be detected several years before diagnosis of Parkinson's disease in primary care. These data can be incorporated into ongoing efforts to identify individuals at the earliest stages of the disease for inclusion in future trials and to help understand progression in the earliest phase of Parkinson's disease.

FUNDING

Parkinson's UK.

Ultrasound-based motion analysis demonstrates bilateral arm hypokinesia during gait in heterozygous PINK1 mutation carriers

Carriers of a single heterozygous PINK1 (PTEN-induced putative kinase 1) gene mutation provide an ideal opportunity to study the development of parkinsonian motor signs from the very beginning. Measuring tools that reliably represent mild motor symptoms could also facilitate the assessment of future neuroprotective therapies and early diagnosis of Parkinson's disease (PD). We investigated nine family members carrying a heterozygous PINK1 mutation in comparison with 25 age-matched healthy controls. Arm kinematics were quantified during treadmill walking at four different speeds using ultrasound-based motion analysis. Heterozygous PINK1 mutation carriers showed a bilateral reduction of arm swing amplitudes (P = 0.003) and arm anteversion (P = 0.001), which was more pronounced on the predominantly affected body side but also was present, albeit to a lesser degree, contralaterally (amplitude P = 0.01, anteversion P = 0.002, repeated measures analysis of covariance [rmANCOVA]). Single post-hoc comparisons revealed similar results for all speeds on both body sides (P < 0.05) except for 2.0 km/h on the less affected side. A single heterozygous mutation in the PINK1 gene is associated with a bilateral dopaminergic dysfunction in this family. Ultrasound-based three-dimensional motion analysis of arm swing during gait is a suitable tool to quantify even subtle hypokinesia in mildly affected PINK1 mutation carriers, which tends to be easily overlooked on the less affected body side during clinical examination. Therefore, this technique is a promising application in early stage PD and in at-risk populations for the disease.

The ongoing pursuit of neuroprotective therapies in Parkinson disease

Many agents developed for neuroprotective treatment of Parkinson disease (PD) have shown great promise in the laboratory, but none have translated to positive results in patients with PD. Potential neuroprotective drugs, such as ubiquinone, creatine and PYM50028, have failed to show any clinical benefits in recent high-profile clinical trials. This 'failure to translate' is likely to be related primarily to our incomplete understanding of the pathogenic mechanisms underlying PD, and excessive reliance on data from toxin-based animal models to judge which agents should be selected for clinical trials. Restricted resources inevitably mean that difficult compromises must be made in terms of trial design, and reliable estimation of efficacy is further hampered by the absence of validated biomarkers of disease progression. Drug development in PD dementia has been mostly unsuccessful; however, emerging biochemical, genetic and pathological evidence suggests a link between tau and amyloid-β deposition and cognitive decline in PD, potentially opening up new possibilities for therapeutic intervention. This Review discusses the most important 'druggable' disease mechanisms in PD, as well as the most-promising drugs that are being evaluated for their potential efficiency in treatment of motor and cognitive impairments in PD.

Multiple system atrophy as emerging template for accelerated drug discovery in α-synucleinopathies

There is evidence that the α-synucleinopathies Parkinson's disease (PD) and the Parkinson variant of multiple system atrophy (MSA-P) overlap at multiple levels. Both disorders are characterized by deposition of abnormally phosphorylated fibrillar α-synuclein within the central nervous system suggesting shared pathophysiological mechanisms. Despite the considerable clinical overlap in the early disease stages, MSA-P, in contrast to PD, is fatal and rapidly progressive. Moreover recent clinical studies have shown that surrogate markers of disease progression can be quantified easily and may reliably depict the rapid course of MSA. We therefore posit that, MSA-P may be exploited as a filter barrier in the development of disease-modifying therapeutic strategies targeting common pathophysiological mechanisms of α-synucleinopathies. This approach might reduce the number of negative phase III clinical trials, and, in turn, shift the available resources to earlier development stages, thereby increasing the number of candidate compounds validated.

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α-synucleinopathies overlap at multiple levels.

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α-synucleinopathies are characterized by an abnormal deposition of α-synuclein.

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Validated surrogate markers in MSA reliably monitor disease progression.

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MSA may serve as a template disease for other α-synucleinopathies.

Pathogenesis-targeted, disease-modifying therapies in Parkinson disease

Parkinson disease is an inexorably progressive neurodegenerative disorder. Multiple attempts have been made to establish therapies for Parkinson disease which provide neuroprotection or disease modification-two related, but not identical, concepts. However, to date, none of these attempts have succeeded. Many challenges exist in this field of research, including a complex multisystem disorder that includes dopaminergic and non-dopaminergic features; poorly understood and clearly multifaceted disease pathogenic mechanisms; a lack of reliable animal models; an absence of effective biomarkers of disease state, progression, and target engagement; and the confounding effects of potent symptomatic therapy. In this article, we will review previous, ongoing, and potential future trials designed to alter the progressive course of the disease from the perspective of the targeted underlying pathogenic mechanisms.

Alimentary, my dear Watson? The challenges of enteric α-synuclein as a Parkinson's disease biomarker

An accurate early diagnostic test for Parkinson's disease (PD) is a critical unmet need. Recently, independent groups using different histological techniques have reported that the presence of alpha-synuclein (α-syn) in colonic biopsy tissue is able to distinguish living patients with PD from those without the disease. In addition, a further study has suggested that the presence of α-syn in colonic biopsy tissue may be evident in early or even prodromal PD. However, several questions remain regarding the translation of these findings into using the assessment of α-syn deposition in the enteric nervous system as a diagnostic biomarker for prodromal PD. Here we address critical issues related to the location and quantification of enteric α-syn, detection of α-syn with currently available histological techniques, timing of detection of α-syn deposition, and, most crucially, whether enteric α-syn can distinguish those with PD from both healthy individuals and individuals with other related diseases. We conclude that, although enteric α-syn is a very exciting prospect, further studies will be vital to determine whether enteric α-syn deposition has the potential to be the biomarker for prodromal PD that the field so desperately seeks.

Neurodegenerative disease status and post-mortem pathology in idiopathic rapid-eye-movement sleep behaviour disorder: an observational cohort study

BACKGROUND

We postulated that idiopathic rapid-eye-movement (REM) sleep behaviour disorder (IRBD) represents the prodromal phase of a Lewy body disorder and that, with sufficient follow-up, most cases would eventually be diagnosed with a clinical defined Lewy body disorder, such as Parkinson's disease (PD) or dementia with Lewy bodies (DLB).

METHODS

Patients from an IRBD cohort recruited between 1991 and 2003, and previously assessed in 2005, were followed up during an additional period of 7 years. In this original cohort, we sought to identify the nature and frequency of emerging defined neurodegenerative syndromes diagnosed by standard clinical criteria. We estimated rates of survival free from defined neurodegenerative disease by means of the Kaplan-Meier method. We further characterised individuals who remained diagnosed as having only IRBD, through dopamine transporter (DAT) imaging, transcranial sonography (TCS), and olfactory testing. We did a neuropathological assessment in three patients who died during follow-up and who had the antemortem diagnosis of PD or DLB.

FINDINGS

Of the 44 participants from the original cohort, 36 (82%) had developed a defined neurodegenerative syndrome by the 2012 assessment (16 patients were diagnosed with PD, 14 with DLB, one with multiple system atrophy, and five with mild cognitive impairment). The rates of neurological-disease-free survival from time of IRBD diagnosis were 65·2% (95% CI 50·9 to 79·5) at 5 years, 26·6% (12·7 to 40·5) at 10 years, and 7·5% (-1·9 to 16·9) at 14 years. Of the four remaining neurological-disease-free individuals who underwent neuroimaging and olfactory tests, all four had decreased striatal DAT uptake, one had substantia nigra hyperechogenicity on TCS, and two had impaired olfaction. In three patients, the antemortem diagnoses of PD and DLB were confirmed by neuropathological examination showing widespread Lewy bodies in the brain, and α-synuclein aggregates in the peripheral autonomic nervous system in one case. In these three patients, neuronal loss and Lewy pathology (α-synuclein-containing Lewy bodies and Lewy neurites) were found in the brainstem nuclei that regulate REM sleep atonia.

INTERPRETATION

Most IRBD individuals from our cohort developed a Lewy body disorder with time. Patients who remained disease-free at follow-up showed markers of increased short-term risk for developing PD and DLB in IRBD, such as decreased striatal DAT binding. Our findings indicate that in most patients diagnosed with IRBD this parasomnia represents the prodromal phase of a Lewy body disorder. IRBD is a candidate for the study of early events and progression of this prodromal phase, and to test disease-modifying strategies to slow or stop the neurodegenerative process.

FUNDING

None.