Perspectives on recent advances in the understanding and treatment of Parkinson’s disease

Revolutionizing our understanding of Parkinson's disease: Dr. Heinz Reichmann's pioneering research and future research direction

Millions of individuals around the world are afflicted with Parkinson's disease (PD), a prevalent and incapacitating neurodegenerative disorder. Dr. Reichmann, a distinguished professor and neurologist, has made substantial advancements in the domain of PD research, encompassing both fundamental scientific investigations and practical applications. His research has illuminated the etiology and treatment of PD, as well as the function of energy metabolism and premotor symptoms. As a precursor to a number of neurotransmitters and neuromodulators that are implicated in the pathophysiology of PD, he has also investigated the application of tryptophan (Trp) derivatives in the disease. His principal findings and insights are summarized and synthesized in this narrative review article, which also emphasizes the challenges and implications for future PD research. This narrative review aims to identify and analyze the key contributions of Reichmann to the field of PD research, with the ultimate goal of informing future research directions in the domain. By examining Reichmann's work, the study seeks to provide a comprehensive understanding of his major contributions and how they can be applied to advance the diagnosis and treatment of PD. This paper also explores the potential intersection of Reichmann's findings with emerging avenues, such as the investigation of Trp and its metabolites, particularly kynurenines, which could lead to new insights and potential therapeutic strategies for managing neurodegenerative disorders like PD.

Aerobic exercise improves depressive symptoms in the unilateral 6-OHDA-lesioned rat model of Parkinson's disease

Aerobic exercise has been shown to have established benefits on motor function in Parkinson's disease (PD). However, the impact of exercise on depressive symptoms in PD remains unclear. This study aimed to investigate the effects of regular exercise, specifically using a forced running wheel, on both motor performance and the prevalence of depression in a unilateral 6-OHDA-lesioned rat model of PD. The behavioral outcomes of exercise were assessed through the rotarod test (RT), forelimb adjusting step test (FAST), sucrose consumption test (SCT), and novelty sucrose splash test (NSST). Our data revealed evident depressive symptoms in the PD animals, characterized by reduced sucrose consumption in the SCT and diminished exploratory activity in the NSST compared to the naïve control group. Specifically, after 11 weeks of exercise, the PD exercise group demonstrated the most significant improvements in sucrose consumption in the SCT. Additionally, this group exhibited reduced immobility and increased exploratory behavior compared to the PD control group in the NSST. Furthermore, the PD exercise group displayed the greatest improvement in correcting forelimb stepping bias. Our results suggested that a regimen of running wheel exercise enhances motor abilities and mitigates the occurrence of depressive behaviors caused by 6-OHDA dopamine depletion in the PD rat model.

Surgical Management of Synucleinopathies

Synucleinopathies represent a diverse set of pathologies with significant morbidity and mortality. In this review, we highlight the surgical management of three synucleinopathies: Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). After examining underlying molecular mechanisms and the medical management of these diseases, we explore the role of deep brain stimulation (DBS) in the treatment of synuclein pathophysiology. Further, we examine the utility of focused ultrasound (FUS) in the treatment of synucleinopathies such as PD, including its role in blood-brain barrier (BBB) opening for the delivery of novel drug therapeutics and gene therapy vectors. We also discuss other recent advances in the surgical management of MSA and DLB. Together, we give a diverse overview of current techniques in the neurosurgical management of these pathologies.

The protective role of exercise against age-related neurodegeneration

Endurance exercise is a widely accessible, low-cost intervention with a variety of benefits to multiple organ systems. Exercise improves multiple indices of physical performance and stimulates pronounced health benefits reducing a range of pathologies including metabolic, cardiovascular, and neurodegenerative disorders. Endurance exercise delays brain aging, preserves memory and cognition, and improves symptoms of neurodegenerative pathologies like Amyotrophic Lateral Sclerosis, Alzheimer's disease, Parkinson's disease, Huntington's disease, and various ataxias. Potential mechanisms underlying the beneficial effects of exercise include neuronal survival and plasticity, neurogenesis, epigenetic modifications, angiogenesis, autophagy, and the synthesis and release of neurotrophins and cytokines. In this review, we discuss shared benefits and molecular pathways driving the protective effects of endurance exercise on various neurodegenerative diseases in animal models and in humans.

Molecular Machinery and Pathophysiology of Mitochondrial Dynamics

Mitochondria are double-membraned organelles that exhibit fluidity. They are the main site of cellular aerobic respiration, providing energy for cell proliferation, migration, and survival; hence, they are called "powerhouses." Mitochondria play an important role in biological processes such as cell death, cell senescence, autophagy, lipid synthesis, calcium homeostasis, and iron balance. Fission and fusion are active processes that require many specialized proteins, including mechanical enzymes that physically alter mitochondrial membranes, and interface proteins that regulate the interaction of these mechanical proteins with organelles. This review discusses the molecular mechanisms of mitochondrial fusion, fission, and physiopathology, emphasizing the biological significance of mitochondrial morphology and dynamics. In particular, the regulatory mechanisms of mitochondria-related genes and proteins in animal cells are discussed, as well as research trends in mitochondrial dynamics, providing a theoretical reference for future mitochondrial research.

Regulation of Tissue Inflammation by 12-Lipoxygenases

Lipoxygenases (LOXs) are lipid metabolizing enzymes that catalyze the di-oxygenation of polyunsaturated fatty acids to generate active eicosanoid products. 12-lipoxygenases (12-LOXs) primarily oxygenate the 12th carbon of its substrates. Many studies have demonstrated that 12-LOXs and their eicosanoid metabolite 12-hydroxyeicosatetraenoate (12-HETE), have significant pathological implications in inflammatory diseases. Increased level of 12-LOX activity promotes stress (both oxidative and endoplasmic reticulum)-mediated inflammation, leading to damage in these tissues. 12-LOXs are also associated with enhanced cellular migration of immune cells-a characteristic of several metabolic and autoimmune disorders. Genetic depletion or pharmacological inhibition of the enzyme in animal models of various diseases has shown to be protective against disease development and/or progression in animal models in the setting of diabetes, pulmonary, cardiovascular, and metabolic disease, suggesting a translational potential of targeting the enzyme for the treatment of several disorders. In this article, we review the role of 12-LOXs in the pathogenesis of several diseases in which chronic inflammation plays an underlying role.

Intrathecal and intracerebroventricular dopamine for Parkinson's disease

While CDD directly to the CSF can provide a constant delivery of the dopaminergic drug resulting in a more stable treatment effect without the limitations of traditional oral therapy without peripheral effects, it is still young and longitudinal data is lacking. These experimental therapies show promise and further investigation into their efficacy and safety could extend the frontiers for management of PD.

Protective effect of hydralazine on a cellular model of Parkinson’s disease: a possible role of hypoxia-inducible factor (HIF)-1α

Parkinson’s disease (PD) is a neurodegenerative disease accompanied by a low expression level of cerebral hypoxia-inducible factor (HIF-1α). Hence, activating the hypoxia-signaling pathway may be a favorable therapeutic approach for curing PD. This study explored the efficacy of hydralazine, a well-known antihypertensive agent, for restoring the impaired HIF-1 signaling in PD, with the aid of 6-hydroxydopamine (6-OHDA)-exposed SH-SY5Y cells. The cytotoxicity of hydralazine and 6-OHDA on the SH-SY5Y cells were evaluated by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and apoptosis detection assays. The activities of malondialdehyde, nitric oxide (NO), ferric reducing antioxidant power (FRAP), and superoxide dismutase (SOD) were also measured. Expression levels of HIF-1α and its downstream genes at the protein level were assessed by Western blotting. Hydralazine showed no toxic effects on SH-SY5Y cells, at the concentration of ≤50 μmol/L. Hydralazine decreased the levels of apoptosis, malondialdehyde, and NO, and increased the activities of FRAP and SOD in cells exposed to 6-OHDA. Furthermore, hydralazine up-regulated the protein expression levels of HIF-1α, vascular endothelial growth factor, tyrosine hydroxylase, and dopamine transporter in the cells also exposed to 6-OHDA, by comparison with the cells exposed to 6-OHDA alone. In summary, hydralazine priming could attenuate the deleterious effects of 6-OHDA on SH-SY5Y cells by increasing cellular antioxidant capacity, as well as the protein levels of HIF-1α and its downstream target genes.

Neurologist Strategies for Optimizing the Parkinson's Disease Clinical Encounter

OBJECTIVE

For patients with Parkinson's disease (PD), effective communication during neurology encounters is critical to ensuring the treatment plan maximizes quality of life. However, few research studies have engaged neurologists as key experts in identifying opportunities to optimize the clinical encounter. In this study, 16 neurologists from 4 clinic sites participated in hour-long semistructured interviews targeting opportunities to better address patients' quality of life needs.

MAIN FINDINGS

Neurologists identified opportunities to meet needs across 4 domains: (1) PD patient education materials and self-management tools to facilitate clinical communication; (2) techniques for improving clinical communication, including strategies for eliciting nonmotor symptoms and contextualizing symptoms to better meet patient quality of life needs; (3) addressing system-level barriers, including time constraints and the lack of an identified specialist referral network; and (4) training in how to lead difficult conversations.

PRINCIPAL CONCLUSIONS

Neurologists identified specific barriers, and proposed solutions, to improving care delivery for patients with PD. Integrating practice tools to address quality of life needs, training neurologists in communication around end-of-life care, and strengthening referral networks for rehabilitation and psychosocial support hold promise for improving quality of life for patients with PD.

Imaging Mass Spectrometry: A New Tool to Assess Molecular Underpinnings of Neurodegeneration

Neurodegenerative diseases are prevalent and devastating. While extensive research has been done over the past decades, we are still far from comprehensively understanding what causes neurodegeneration and how we can prevent it or reverse it. Recently, systems biology approaches have led to a holistic examination of the interactions between genome, metabolome, and the environment, in order to shed new light on neurodegenerative pathogenesis. One of the new technologies that has emerged to facilitate such studies is imaging mass spectrometry (IMS). With its ability to map a wide range of small molecules with high spatial resolution, coupled with the ability to quantify them at once, without the need for a priori labeling, IMS has taken center stage in current research efforts in elucidating the role of the metabolome in driving neurodegeneration. IMS has already proven to be effective in investigating the lipidome and the proteome of various neurodegenerative diseases, such as Alzheimer's, Parkinson's, Huntington's, multiple sclerosis, and amyotrophic lateral sclerosis. Here, we review the IMS platform for capturing biological snapshots of the metabolic state to shed more light on the molecular mechanisms of the diseased brain.

Switching from an oral dopamine receptor agonist to rotigotine transdermal patch: a review of clinical data with a focus on patient perspective

INTRODUCTION

Dopamine receptor agonists (DAs) are commonly used to treat Parkinson's disease (PD) and restless legs syndrome (RLS). In certain situations, switching from oral DAs to rotigotine transdermal patch may be beneficial for the patient (e.g., optimal symptom control/side effects/perioperative management, preference for once-daily/non-oral administration, RLS augmentation treatment). Areas covered: This narrative review summarizes available data on DA dose equivalency, dose conversions, switching schedules, safety, tolerability, efficacy and patient treatment preferences of switching from oral DAs to rotigotine (and vice versa) in patients with PD/RLS. The studies were identified in a PubMed search (up to 8 November 2016) using terms ('dopamine receptor agonist' OR 'rotigotine') AND 'switch'. Expert commentary: Randomized controlled studies often do not address the challenges clinicians face in practice, e.g., switching medications within the same class when dosing is not a one-to-one ratio. The authors describe three open-label studies in PD where oral DAs were successfully switched to rotigotine, and review three studies in RLS where oral DAs/levodopa were switched to rotigotine. Finally, the authors provide a suggested tool for switching from oral DAs to rotigotine, which includes dose conversion factors and switching schedules. The authors' view is that low-dose oral DAs (equivalent to ≤8 mg/24 h rotigotine) may be switched overnight.

CNS repurposing - Potential new uses for old drugs: Examples of screens for Alzheimer's disease, Parkinson's disease and spasticity

Drug repurposing is recently gaining increasing attention, not just from pharmaceutical companies but also from government agencies in an attempt to generate new medications to address increasing unmet medical needs in a cost effective and expedite manner. There are several approaches to identify novel indications for known drugs. Many are based on rational selection e.g. the known or a new mechanism of action of a drug. This review will focus rather on phenotypic or high content screening of compounds in models that are believed to be predictive of effectiveness of compounds irrespective of their mechanism of action. Three short cases studies of screens for Alzheimer's disease, Parkinson's disease and spasticity will be given as examples. This article is part of the Special Issue entitled 'Drug Repurposing: old molecules, new ways to fast track drug discovery and development for CNS disorders'.

Voluntary Physical Exercise Improves Subsequent Motor and Cognitive Impairments in a Rat Model of Parkinson's Disease

Background: Parkinson’s disease (PD) is typically characterized by impairment of motor function. Gait disturbances similar to those observed in patients with PD can be observed in animals after injection of neurotoxin 6-hydroxydopamine (6-OHDA) to induce unilateral nigrostriatal dopamine depletion. Exercise has been shown to be a promising non-pharmacological approach to reduce the risk of neurodegenerative disease. Methods: In this study, we investigated the long-term effects of voluntary running wheel exercise on gait phenotypes, depression, cognitive, rotational behaviors as well as histology in a 6-OHDA-lesioned rat model of PD. Results: We observed that, when compared with the non-exercise controls, five-week voluntary exercise alleviated and postponed the 6-OHDA-induced gait deficits, including a significantly improved walking speed, step/stride length, base of support and print length. In addition, we found that the non-motor functions, such as novel object recognition and forced swim test, were also ameliorated by voluntary exercise. However, the rotational behavior of the exercise group did not show significant differences when compared with the non-exercise group. Conclusions: We first analyzed the detailed spatiotemporal changes of gait pattern to investigate the potential benefits after long-term exercise in the rat model of PD, which could be useful for future objective assessment of locomotor function in PD or other neurological animal models. Furthermore, these results suggest that short-term voluntary exercise is sufficient to alleviate cognition deficits and depressive behavior in 6-OHDA lesioned rats and long-term treatment reduces the progression of motor symptoms and elevates tyrosine hydroxylase (TH), Brain-derived neurotrophic factor (BDNF), bone marrow tyrosine kinase in chromosome X (BMX) protein expression level without affecting dopaminergic (DA) neuron loss in this PD rat model.

Privileged scaffolds as MAO inhibitors: Retrospect and prospects

This review aims to be a comprehensive, authoritative, critical, and readable review of general interest to the medicinal chemistry community because it focuses on the pharmacological, chemical, structural and computational aspects of diverse chemical categories as monoamine oxidase inhibitors (MAOIs). Monoamine oxidases (MAOs), namely MAO-A and MAO-B represent an enormously valuable class of neuronal enzymes embodying neurobiological origin and functions, serving as potential therapeutic target in neuronal pharmacotherapy, and hence we have coined the term "Neurozymes" which is being introduced for the first time ever. Nowadays, therapeutic attention on MAOIs engrosses two imperative categories; MAO-A inhibitors, in certain mental disorders such as depression and anxiety, and MAO-B inhibitors, in neurodegenerative disorders like Alzheimer's disease (AD) and Parkinson's disease (PD). The use of MAOIs declined due to some potential side effects, food and drug interactions, and introduction of other classes of drugs. However, curiosity in MAOIs is reviving and the recent developments of new generation of highly selective and reversible MAOIs, have renewed the therapeutic prospective of these compounds. The initial section of the review emphasizes on the detailed classification, structural and binding characteristics, therapeutic potential, current status and future challenges of the privileged pharmacophores. However, the chemical prospective of privileged scaffolds such as; aliphatic and aromatic amines, amides, hydrazines, azoles, diazoles, tetrazoles, indoles, azines, diazines, xanthenes, tricyclics, benzopyrones, and more interestingly natural products, along with their conclusive SARs have been discussed in the later segment of review. The last segment of the article encompasses some patents granted in the field of MAOIs, in a simplistic way.

Stem cell therapies in age-related neurodegenerative diseases and stroke

Aging, a complex process associated with various structural, functional and metabolic changes in the brain, is an important risk factor for neurodegenerative diseases and stroke. These diseases share similar neuropathological changes, such as the formation of misfolded proteins, oxidative stress, loss of neurons and synapses, dysfunction of the neurovascular unit (NVU), reduction of self-repair capacity, and motor and/or cognitive deficiencies. In addition to gray matter dysfunction, the plasticity and repair capacity of white matter also decrease with aging and contribute to neurodegenerative diseases. Aging not only renders patients more susceptible to these disorders, but also attenuates their self-repair capabilities. In addition, low drug responsiveness and intolerable side effects are major challenges in the prevention and treatment of senile diseases. Thus, stem cell therapies-characterized by cellular plasticity and the ability to self-renew-may be a promising strategy for aging-related brain disorders. Here, we review the common pathophysiological changes, treatments, and the promises and limitations of stem cell therapies in age-related neurodegenerative diseases and stroke.

Using a smartphone-based self-management platform to support medication adherence and clinical consultation in Parkinson's disease

The progressive nature of Parkinson’s disease, its complex treatment regimens and the high rates of comorbid conditions make self-management and treatment adherence a challenge. Clinicians have limited face-to-face consultation time with Parkinson’s disease patients, making it difficult to comprehensively address non-adherence. Here we share the results from a multi-centre (seven centres) randomised controlled trial conducted in England and Scotland to assess the impact of using a smartphone-based Parkinson’s tracker app to promote patient self-management, enhance treatment adherence and quality of clinical consultation. Eligible Parkinson’s disease patients were randomised using a 1:1 ratio according to a computer-generated random sequence, stratified by centre and using blocks of variable size, to intervention Parkinson’s Tracker App or control (Treatment as Usual). Primary outcome was the self-reported score of adherence to treatment (Morisky medication adherence scale −8) at 16 weeks. Secondary outcomes were Quality of Life (Parkinson’s disease questionnaire −39), quality of consultation for Parkinson’s disease patients (Patient-centred questionnaire for Parkinson’s disease), impact on non-motor symptoms (Non-motor symptoms questionnaire), depression and anxiety (Hospital anxiety and depression scale) and beliefs about medication (Beliefs about Medication Questionnaire) at 16 weeks. Primary and secondary endpoints were analysed using a generalised linear model with treatment as the fixed effect and baseline measurement as the covariate. 158 patients completed the study (Parkinson’s tracker app = 68 and TAU = 90). At 16 weeks Parkinson’s tracker app significantly improved adherence, compared to treatment as usual (mean difference: 0.39, 95%CI 0.04–0.74; p = 0.0304) with no confounding effects of gender, number of comorbidities and age. Among secondary outcomes, Parkinson’s tracker app significantly improved patients’ perception of quality of consultation (0.15, 95% CI 0.03 to 0.27; p = 0.0110). The change in non-motor symptoms was −0.82 (95% CI −1.75 to 0.10; p = 0.0822). 72% of participants in the Parkinson’s tracker app group continued to use and engage with the application throughout the 16-week trial period. The Parkinson’s tracker app can be an effective and novel way of enhancing self-reported medication adherence and quality of clinical consultation by supporting self-management in Parkinson’s disease in patients owning smartphones. Further work is recommended to determine whether the benefits of the intervention are maintained beyond the 16 week study period.

A smartphone-based application improves treatment adherence of patients with Parkinson’s disease (PD). Rashmi Lakshminarayana, from uMotif Ltd, and researchers from the UK and The Netherlands describe the results of a 16 week trial of a Parkinson’s tracker app (PTA) that randomised 215 patients from seven different health centres. Patients using the app reported significantly better adherence to their medication plan compared with control patients who continued their treatment as usual. Interestingly, using the PTA also improved the patients’ perception of the quality of their clinical care, possibly as a result of feeling more involved and in control of their care. These findings suggest that by sending medication reminders and tracking symptoms, the app can help patients with Parkinson’s self-manage their increasingly complex treatment regimen as the disease progresses.

Combination of acamprosate and baclofen as a promising therapeutic approach for Parkinson's disease

Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterised by the loss of dopaminergic nigrostriatal neurons but which involves the loss of additional neurotransmitter pathways. Mono- or polytherapeutic interventions in PD patients have declining efficacy long-term and no influence on disease progression. The systematic analysis of available genetic and functional data as well as the substantial overlap between Alzheimer’s disease (AD) and PD features led us to repurpose and explore the effectiveness of a combination therapy (ABC) with two drugs – acamprosate and baclofen – that was already effective in AD animal models, for the treatment of PD. We showed in vitro that ABC strongly and synergistically protected neuronal cells from oxidative stress in the oxygen and glucose deprivation model, as well as dopaminergic neurons from cell death in the 6-hydroxydopamine (6-OHDA) rat model. Furthermore, we showed that ABC normalised altered motor symptoms in vivo in 6-OHDA-treated rats, acting by protecting dopaminergic cell bodies and their striatal terminals. Interestingly, ABC also restored a normal behaviour pattern in lesioned rats suggesting a symptomatic effect, and did not negatively interact with L-dopa. Our results demonstrate the potential value of combining repurposed drugs as a promising new strategy to treat this debilitating disease.

Early versus delayed initiation of pharmacotherapy in Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease and pathologically is characterised by a progressive loss of dopaminergic cells of the nigrostriatal pathway. Clinically, PD is mainly defined by the presence of the motor symptoms of bradykinesia, rigidity, rest tremor and postural instability, but non-motor symptoms such as depression, dementia and autonomic disturbances are recognised as integral parts of the disease. Although pharmacotherapy for PD was introduced almost 50 years ago, and has improved significantly over the intervening period, the timing of initiation of treatment in newly diagnosed PD remains controversial. While some physicians favour an early start of pharmacotherapy at or soon after diagnosis, others prefer to delay pharmacological treatment until a certain degree of disability has developed. This article aims to discuss the advantages and disadvantages of both strategies by exploring their effects on symptoms, disease progression and quality of life. Although the data on putative disease-modifying effects of early pharmacological intervention in PD are still inconclusive, we believe that the most important indication for an early initiation of anti-parkinsonian treatment should be to maintain the quality of life of PD patients and to secure their socioeconomic status as long as possible.

Web-based telemonitoring and delivery of caregiver support for patients with Parkinson disease after deep brain stimulation: protocol

Background

The increasing number of patients, the high costs of management, and the chronic progress of the disease that prevents patients from performing even simple daily activities make Parkinson disease (PD) a complex pathology with a high impact on society. In particular, patients implanted with deep brain stimulation (DBS) electrodes face a highly fragile stabilization period, requiring specific support at home. However, DBS patients are followed usually by untrained personnel (caregivers or family), without specific care pathways and supporting systems.

Objective

This projects aims to (1) create a reference consensus guideline and a shared requirements set for the homecare and monitoring of DBS patients, (2) define a set of biomarkers that provides alarms to caregivers for continuous home monitoring, and (3) implement an information system architecture allowing communication between health care professionals and caregivers and improving the quality of care for DBS patients.

Methods

The definitions of the consensus care pathway and of caregiver needs will be obtained by analyzing the current practices for patient follow-up through focus groups and structured interviews involving health care professionals, patients, and caregivers. The results of this analysis will be represented in a formal graphical model of the process of DBS patient care at home. To define the neurophysiological biomarkers to be used to raise alarms during the monitoring process, neurosignals will be acquired from DBS electrodes through a new experimental system that records while DBS is turned ON and transmits signals by radiofrequency. Motor, cognitive, and behavioral protocols will be used to study possible feedback/alarms to be provided by the system. Finally, a set of mobile apps to support the caregiver at home in managing and monitoring the patient will be developed and tested in the community of caregivers that participated in the focus groups. The set of developed apps will be connected to the already existing WebBioBank Web-based platform allowing health care professionals to manage patient electronic health records and neurophysiological signals. New modules in the WebBioBank platform will be implemented to allow integration and data exchange with mobile health apps.

Results

The results of this project will provide a novel approach to long-term evaluation of patients with chronic, severe conditions in the homecare environment, based on caregiver empowerment and tailored applications developed according to consensus care pathways established by clinicians.

Conclusions

The creation of a direct communication channel between health care professionals and caregivers can benefit large communities of patients and would represent a scalable experience in integrating data and information coming from a clinical setting to those in home monitoring.

Smartphone- and internet-assisted self-management and adherence tools to manage Parkinson's disease (SMART-PD): study protocol for a randomised controlled trial (v7; 15 August 2014)

BACKGROUND

Nonadherence to treatment leads to suboptimal treatment outcomes and enormous costs to the economy. This is especially important in Parkinson's disease (PD). The progressive nature of the degenerative process, the complex treatment regimens and the high rates of comorbid conditions make treatment adherence in PD a challenge. Clinicians have limited face-to-face consultation time with PD patients, making it difficult to comprehensively address non-adherence. The rapid growth of digital technologies provides an opportunity to improve adherence and the quality of decision-making during consultation. The aim of this randomised controlled trial (RCT) is to evaluate the impact of using a smartphone and web applications to promote patient self-management as a tool to increase treatment adherence and working with the data collected to enhance the quality of clinical consultation.

METHODS/DESIGN

A 4-month multicentre RCT with 222 patients will be conducted to compare use of a smartphone- and internet-enabled Parkinson's tracker smartphone app with treatment as usual for patients with PD and/or their carers. The study investigators will compare the two groups immediately after intervention. Seven centres across England (6) and Scotland (1) will be involved. The primary objective of this trial is to assess whether patients with PD who use the app show improved medication adherence compared to those receiving treatment as usual alone. The secondary objectives are to investigate whether patients who receive the app and those who receive treatment as usual differ in terms of quality of life, quality of clinical consultation, overall disease state and activities of daily living. We also aim to investigate the experience of those receiving the intervention by conducting qualitative interviews with a sample of participants and clinicians, which will be administered by independent researchers.

TRIAL REGISTRATION

ISRCTN45824264 (registered 5 November 2013).

Exercise-enhanced neuroplasticity targeting motor and cognitive circuitry in Parkinson's disease

Exercise interventions in individuals with Parkinson's disease incorporate goal-based motor skill training to engage cognitive circuitry important in motor learning. With this exercise approach, physical therapy helps with learning through instruction and feedback (reinforcement) and encouragement to perform beyond self-perceived capability. Individuals with Parkinson's disease become more cognitively engaged with the practice and learning of movements and skills that were previously automatic and unconscious. Aerobic exercise, regarded as important for improvement of blood flow and facilitation of neuroplasticity in elderly people, might also have a role in improvement of behavioural function in individuals with Parkinson's disease. Exercises that incorporate goal-based training and aerobic activity have the potential to improve both cognitive and automatic components of motor control in individuals with mild to moderate disease through experience-dependent neuroplasticity. Basic research in animal models of Parkinson's disease is beginning to show exercise-induced neuroplastic effects at the level of synaptic connections and circuits.

Diapocynin prevents early Parkinson's disease symptoms in the leucine-rich repeat kinase 2 (LRRK2R¹⁴⁴¹G) transgenic mouse

The most prominent mechanism proposed for death of dopaminergic neurons in Parkinson's disease (PD) is elevated generation of reactive oxygen/nitrogen species (ROS/RNS). Recent studies suggest that ROS produced during PD pathogenesis may contribute to cytotoxicity in cell culture models of PD. We hypothesized that inhibition of ROS production would prevent PD symptoms in the LRRK2(R1441G) transgenic (tg) mouse model of PD. These mice overexpress a mutant form of leucine-rich repeat kinase 2 (LRRK2) and are reported to develop PD-like symptoms at approximately 10 months of age. Despite similar expression of the transgene, our colony did not recapitulate the same type of motor dysfunction originally reported. However, tests of motor coordination (pole test, Rotor-Rod) revealed a significant defect in LRRK2(R1441G) mice by 16 months of age. LRRK2(R1441G) tg mice, or wild type littermates, were given diapocynin (200mg/kg, a proposed NADPH oxidase inhibitor) three times per week by oral gavage starting at 12 weeks of age. Decreased performance on the pole test and Rotor-Rod in the LRRK2(R1441G) mice was prevented with diapocynin treatment. No loss in open field movement or rearing was found. As expected, tyrosine hydroxylase staining was similar in both the substantia nigra and striatum in all treatment groups. Together these data demonstrate that diapocynin is a viable agent for protection of neurobehavioral function.

Pramipexole reduces phosphorylation of α-synuclein at serine-129

α-Synuclein is a central component of the pathogenesis of Parkinson’s disease (PD). Phosphorylation at serine-129 represents an important post-translational modification and constitutes the major form of the protein in Lewy bodies. Several kinases have been implicated in the phosphorylation of α-synuclein. The targeting of kinase pathways as a potential to influence the pathogenesis of PD is an important focus of attention, given that mutations of specific kinases (LRRK2 and PINK1) are causes of familial PD. Pramipexole (PPX) is a dopamine agonist developed for the symptomatic relief of PD. Several in vitro and in vivo laboratory studies have demonstrated that PPX exerts neuroprotective properties in model systems of relevance to PD. The present study demonstrates that PPX inhibits the phosphorylation of α-synuclein and that this is independent of dopamine receptor activation. PPX blocks the increase in phosphorylated α-synuclein induced by inhibition of the ubiquitin proteasomal system. The phosphorylation of α-synuclein occurs in part at least through casein kinase 2, and PPX in turn reduces the phosphorylation of this enzyme, thereby inhibiting its activity. Thus, PPX decreases the phosphorylation of α-synuclein, and this mechanism may contribute to its protective properties in PD models.

Nutraceuticals and their preventive or potential therapeutic value in Parkinson's disease

Parkinson's disease (PD) is the second most common aging-related disorder in the world, after Alzheimer's disease. It is characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta and other parts of the brain, leading to motor impairment, cognitive impairment, and dementia. Current treatment methods, such as L-dopa therapy, are focused only on relieving symptoms and delaying progression of the disease. To date, there is no known cure for PD, making prevention of PD as important as ever. More than a decade of research has revealed a number of major risk factors, including oxidative stress and mitochondrial dysfunction. Moreover, numerous nutraceuticals have been found to target and attenuate these risk factors, thereby preventing or delaying the progression of PD. These nutraceuticals include vitamins C, D, E, coenzyme Q10, creatine, unsaturated fatty acids, sulfur-containing compounds, polyphenols, stilbenes, and phytoestrogens. This review examines the role of nutraceuticals in the prevention or delay of PD as well as the mechanisms of action of nutraceuticals and their potential applications as therapeutic agents, either alone or in combination with current treatment methods.

Mitochondrial diseases

Mitochondria have a crucial role in cellular bioenergetics and apoptosis, and thus are important to support cell function and in determination of cell death pathways. Inherited mitochondrial diseases can be caused by mutations of mitochondrial DNA or of nuclear genes that encode mitochondrial proteins. Although many mitochondrial disorders are multisystemic, some are tissue specific--eg, optic neuropathy, sensorineural deafness, and type 2 diabetes mellitus. In the past few years, several disorders have been associated with mutations of nuclear genes responsible for mitochondrial DNA maintenance and function, and the potential contribution of mitochondrial abnormalities to progressive neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease has been recognised. The process of mitochondrial fission-fusion has become a focus of attention in human disease. Importantly, the mitochondrion is now a target for therapeutic interventions that encompass small molecules, transcriptional regulation, and genetic manipulation, offering opportunities to treat a diverse range of diseases.

Targeting mitochondria for neuroprotection in Parkinson's disease

SIGNIFICANCE

Several genetic causes of familial Parkinson's disease (PD) have now been identified and include mutations of genes encoding mitochondrial proteins. Mitochondrial complex I toxins can induce dopaminergic cell death and produce a parkinsonian state. Importantly, defects of mitochondrial function have been identified in postmortem substantia nigra from pathologically proven cases of PD.

RECENT ADVANCES

These observations provide compelling evidence to support the notion that mitochondria play an important role in the pathogenesis of PD. Thus, targeting mitochondrial function to delay or prevent neuronal cell death would represent a logical means to modify the course of this disease. Several attempts have already been made in this respect, and have been tested in clinical trial.

CRITICAL ISSUES

To date, there is no unequivocal evidence for an effective intervention to slow the disease. However, several novel mitochondrial targets are now emerging, including the potential to manipulate the mitochondrial pool to maintain function via biogenesis and mitophagy.

FUTURE DIRECTIONS

This development in drug targets needs to be supported by a parallel improvement in clinical trial design to be able to detect a neuroprotective or disease-modifying effect over a reasonable time scale.

Mitochondrial pathology in Parkinson's disease

The last 25 years have witnessed remarkable advances in our understanding of the etiology and pathogenesis of Parkinson's disease. The ability to undertake detailed biochemical analyses of the Parkinson's disease postmortem brain enabled the identification of defects of mitochondrial and free-radical metabolism. The discovery of the first gene mutation for Parkinson's disease, in alpha-synuclein, ushered in the genetic era for the disease and the subsequent finding of several gene mutations causing parkinsonism, 15 at the time of writing. Technological advances both in sequencing technology and software analysis have allowed association studies of sufficiently large size accurately to describe genes conferring an increased risk for Parkinson's disease. What has been so surprising is the convergence of these 2 separate disciplines (biochemistry and genetics) in terms of reinforcing the importance of the same pathways (ie, mitochondrial dysfunction and free-radical metabolism). Other pathways are also important in pathogenesis, including protein turnover, inflammation, and post-translational modification, particularly protein phosphorylation and ubiquitination. However, even these additional pathways overlap with each other and with those of mitochondrial dysfunction and oxidative stress. This review explores these concepts with particular relevance to mitochondrial involvement.

Transgenic expression and activation of PGC-1α protect dopaminergic neurons in the MPTP mouse model of Parkinson's disease

Mitochondrial dysfunction and oxidative stress occur in Parkinson's disease (PD), but little is known about the molecular mechanisms controlling these events. Peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) is a transcriptional coactivator that is a master regulator of oxidative stress and mitochondrial metabolism. We show here that transgenic mice overexpressing PGC-1α in dopaminergic neurons are resistant against cell degeneration induced by the neurotoxin MPTP. The increase in neuronal viability was accompanied by elevated levels of mitochondrial antioxidants SOD2 and Trx2 in the substantia nigra of transgenic mice. PGC-1α overexpression also protected against MPTP-induced striatal loss of dopamine, and mitochondria from PGC-1α transgenic mice showed an increased respiratory control ratio compared with wild-type animals. To modulate PGC-1α, we employed the small molecular compound, resveratrol (RSV) that protected dopaminergic neurons against the MPTP-induced cell degeneration almost to the same extent as after PGC-1α overexpression. As studied in vitro, RSV activated PGC-1α in dopaminergic SN4741 cells via the deacetylase SIRT1, and enhanced PGC-1α gene transcription with increases in SOD2 and Trx2. Taken together, the results reveal an important function of PGC-1α in dopaminergic neurons to combat oxidative stress and increase neuronal viability. RSV and other compounds acting via SIRT1/PGC-1α may prove useful as neuroprotective agents in PD and possibly in other neurological disorders.

Aetiopathogenesis of Parkinson's disease

Parkinson's disease (PD) is characterised both clinically and pathologically by features that distinguish it from other parkinsonian disorders including, for instance, multiple system atrophy and progressive supranuclear palsy. The aetiologies of PD includes both genetic and environmental influences. Several single gene causes of autosomal dominant and recessive PD have been described. Recent genome-wide association (GWA) studies have identified a number of risk alleles for PD. No specific environmental cause has been defined but several factors have been described which influence the risk for PD. Mitochondrial dysfunction, free radical mediated damage, inflammatory change and proteasomal dysfunction have been thought to play a role in PD pathogenesis. Autophagy is now recognised as an important component of the cell's mechanism for protein turnover and has relevance for PD. There is some convergence and overlap of pathogenetic pathways between environmental and genetic factors. The importance of identifying the molecular and biochemical events that lead to PD lies in the prospect that novel drug targets will emerge and that new compounds will be developed that slow the progression of the disease.

Move for change part I: a European survey evaluating the impact of the EPDA Charter for People with Parkinson's disease

BACKGROUND AND PURPOSE

The 1997 European Parkinson's Disease Association's (EPDA) Charter for People with Parkinson's disease (PD) outlines their rights in terms of standards of care. It states that all patients have the right to: be referred to a doctor with a special interest in PD; receive an accurate diagnosis; have access to support services; receive continuous care; and take part in managing their illness. Move for Change is a three-part series of pan-European patient surveys based on this Charter.

METHODS

This first survey, consisting of 23 questions, focusing on the initial two points of the Charter, was administered online through the EPDA and affiliated patient associations' Web sites. Of 2149 forms received from 35 European countries, 2068 (96.2%) were analyzed, with the remainder excluded, mainly due to incomplete responses.

RESULTS

The majority of patients were diagnosed within 2 years from the onset of first symptoms (82.7%; range, <1 year to ≥5 years). In relation to diagnosis delivery, 45.3% of patients stated that it was 'poor' or 'very poor'. During the 2 years following diagnosis, 43.8% of respondents had never seen a PD specialist. Care was usually overseen by generically active neurologists (92.5%) or family doctors (81.0%), with considerable overlap between the two.

CONCLUSIONS

  These data highlight challenges that patients with PD face during the period of diagnosis, despite introduction of the Charter. These findings can assist healthcare professionals and policy makers in improving the level of care for patients and their families across Europe, and we offer suggestions about how this can be achieved.

Parkinson's disease therapeutics: new developments and challenges since the introduction of levodopa

The demonstration that dopamine loss is the key pathological feature of Parkinson's disease (PD), and the subsequent introduction of levodopa have revolutionalized the field of PD therapeutics. This review will discuss the significant progress that has been made in the development of new pharmacological and surgical tools to treat PD motor symptoms since this major breakthrough in the 1960s. However, we will also highlight some of the challenges the field of PD therapeutics has been struggling with during the past decades. The lack of neuroprotective therapies and the limited treatment strategies for the nonmotor symptoms of the disease (ie, cognitive impairments, autonomic dysfunctions, psychiatric disorders, etc.) are among the most pressing issues to be addressed in the years to come. It appears that the combination of early PD nonmotor symptoms with imaging of the nigrostriatal dopaminergic system offers a promising path toward the identification of PD biomarkers, which, once characterized, will set the stage for efficient use of neuroprotective agents that could slow down and alter the course of the disease.

Monoamine oxidase B inhibitors for the treatment of Parkinson's disease: a review of symptomatic and potential disease-modifying effects

Parkinson's disease is a disorder characterized pathologically by progressive neurodegeneration of the dopaminergic cells of the nigrostriatal pathway. Although the resulting dopamine deficiency is the cause of the typical motor features of Parkinson's disease (bradykinesia, rigidity, tremor), additional non-motor symptoms appear at various timepoints and are the result of non-dopamine nerve degeneration. Monoamine oxidase B (MAO-B) inhibitors are used in the symptomatic treatment of Parkinson's disease as they increase synaptic dopamine by blocking its degradation. Two MAO-B inhibitors, selegiline and rasagiline, are currently licensed in Europe and North America for the symptomatic improvement of early Parkinson's disease and to reduce off-time in patients with more advanced Parkinson's disease and motor fluctuations related to levodopa. A third MAO-B inhibitor (safinamide), which also combines additional non-dopaminergic properties of potential benefit to Parkinson's disease, is currently under development in phase III clinical trials as adjuvant therapy to either a dopamine agonist or levodopa. MAO-B inhibitors have also been studied extensively for possible neuroprotective or disease-modifying actions. There is considerable laboratory evidence that MAO-B inhibitors do exert some neuroprotective properties, at least in the Parkinson's disease models currently available. However, these models have significant limitations and caution is required in assuming that such results may easily be extrapolated to clinical trials. Rasagiline 1 mg/day has been shown to provide improved motor control in terms of Unified Parkinson's Disease Rating Scale (UPDRS) score at 18 months in those patients with early disease who began the drug 9 months before a second group. There are a number of possible explanations for this effect that may include a disease-modifying action; however, the US FDA recently declined an application for the licence of rasagiline to be extended to cover disease modification.

The use of carer assisted adherence therapy for people with Parkinson's disease and their carers (CAAT-PARK): study protocol for a randomised controlled trial

BACKGROUND

Pharmacological intervention is essential for managing the symptoms of Parkinson's disease. Adherence to medication regimens however is a major problem. Poor adherence leads to significant motor deterioration and inadequate symptom control. This results in poor quality of life. Whilst interventions to improve medication adherence have shown considerable benefit in other chronic conditions, the efficacy of such treatments in Parkinson's disease is less well researched. Many people with Parkinson's disease require substantial support from spouse/caregivers. This often extends to medication taking. Consequently, spouse/caregiver's support for timely medication management is paramount. We aim to investigate the benefit of a novel intervention, Carer Assisted Adherence Therapy, for improving medication adherence and quality of life in people with Parkinson's disease. Adherence therapy may help to optimise the efficacy of anti-parkinsonian agents, subsequently improving clinical outcomes.

METHODS/DESIGN

A parallel, randomised controlled trial will be conducted to investigate whether carer assisted adherence therapy is effective for improving medication adherence and quality of life. We aim to recruit 40 patient/carer pairs into each group. Participants will be randomly assigned by the Clinical Research Trials Unit at the University of East Anglia. Adherence therapy is a brief cognitive-behavioural approach aimed at facilitating a process of shared decision making. The central theory is that when patients make shared choices with a professional they are more likely to continue with those choices because they are personally owned and meaningful. Outcomes will be rates of adherence and quality of life, determined by the Morisky Medication Adherence Scale-4 and the Parkinson's disease Questionnaire-39 respectively. Assessments will take place post randomisation, immediately post intervention and 12-weeks post randomisation. Primary outcomes are adherence and quality of life at 12-week follow-up. Efficacy will be determined using intention-to-treat analysis. Independent samples t-tests will compare mean changes between groups from baseline to follow-up. Per protocol analysis will be conducted based on individuals with no major protocol deviation. Where imbalances in baseline characteristics are identified, an adjusted analysis will be performed using a regression model. Analysis will be masked to treatment allocation.

TRIAL REGISTRATION

ISRCTN: ISRCTN07830951.

Etiology and pathogenesis of Parkinson's disease

The past 25 years have seen a major expansion of knowledge concerning the cause of Parkinson's disease provided by an understanding of environmental and genetic factors that underlie the loss of nigral dopaminergic neurons. Based on the actions of toxins, postmortem investigations, and gene defects responsible for familial Parkinson's disease, there is now a general consensus about the mechanisms of cell death that contribute to neuronal loss in Parkinson's disease. Mitochondrial dysfunction, oxidative stress, altered protein handling, and inflammatory change are considered to lead to cell dysfunction and death by apoptosis or autophagy. Ageing is the single most important risk factor for Parkinson's disease, and the biochemical changes that are a consequence of aging amplify these abnormalities in Parkinson's disease brain. What remains to be determined is the combination and sequence of events leading to cell death and whether this is identical in all brain regions where pathology occurs and in all individuals with Parkinson's disease. Focusing on those events that characterize Parkinson's disease, namely, mitochondrial dysfunction and Lewy body formation, may be the key to further advancing the understanding of pathogenesis and to taking these mechanisms forward as a means of defining targets for neuroprotection.

Parkinson's disease mouse models in translational research

Animal models with high predictive power are a prerequisite for translational research. The closer the similarity of a model to Parkinson’s disease (PD), the higher is the predictive value for clinical trials. An ideal PD model should present behavioral signs and pathology that resemble the human disease. The increasing understanding of PD stratification and etiology, however, complicates the choice of adequate animal models for preclinical studies. An ultimate mouse model, relevant to address all PD-related questions, is yet to be developed. However, many of the existing models are useful in answering specific questions. An appropriate model should be chosen after considering both the context of the research and the model properties. This review addresses the validity, strengths, and limitations of current PD mouse models for translational research.

The role of axonopathy in Parkinson's disease

New genetic and environmental studies of Parkinson's disease have revealed early problems in synaptic function and connectivity indicating that axonal impairment may be an important hallmark in this disorder. Since many studies suggest that axonal dysfunction precedes cell body loss, it is critical to target axons with treatments aimed at preserving "connectivity" as well as to develop and verify "biomarkers" with which to assess disease progression and drug efficacy.

Neuroprotection in Parkinson's disease

A major focus in Parkinson's disease (PD) research is to produce drugs or other interventions that can slow or stop clinical progression. This should include an effect on both motor and non-motor symptoms and so target dopaminergic and non-dopaminergic pathways. It is logical to assume that the best chance of developing such therapies will be based on forming a better understanding of the aetiology and pathogenesis of PD and to identify critical molecular targets. There have been great advances in finding different genetic causes and risk factors for PD, but less so in the discovery of environmental contributions. The separate genetic causes still share common pathways to cell dysfunction and death, and these interconnect at several levels. Despite the major advances in genetics and PD pathogenesis, we still do not have good models of PD that can be used with confidence to accurately predict the effect of drugs on disease progression. Clinical trial design and study population selection are also areas that represent significant challenges to testing any putative neuro-protective agent. Several drugs have attracted attention as potential neuroprotective agents in PD. There are numerous studies demonstrating beneficial effects in the laboratory, but clinical efficacy for neuroprotection remains unproven.

Molecular and clinical prodrome of Parkinson disease: implications for treatment

The development of interventions to slow or prevent progression represents an important aim for current research into Parkinson disease (PD). General agreement prevails that success in this endeavor will depend on a clearer understanding of etiology and pathogenesis, and several important advances have recently been made, particularly in defining the genetic causes of PD. Studies of the biochemical consequences of the mutations that cause familial PD, and postmortem brain studies of idiopathic, sporadic PD, have highlighted mitochondrial dysfunction, oxidative stress, and protein metabolism by the ubiquitin-proteasomal and autophagy systems as being central to pathogenesis. In parallel with advances in etiopathogenesis, a clearer perception has developed of the clinical prodrome of PD, offering an opportunity to identify individuals who are at risk of PD, as well as those in the earliest clinical phase of the disease that might even precede the onset of motor symptoms. These populations are potentially the most suitable in which to test new protective therapies, and to study potential peripheral markers of disease progression. The awareness of the early symptomatic period of PD also raises the possibility of providing treatments that not only improve motor function but might also favorably modify outcome.

Parkinson's disease as a disconnection syndrome

Parkinson's disease (PD) is a major neurodegenerative disorder that is usually considered in terms of midbrain and basal ganglia dysfunction. Regarding PD instead as a disconnection syndrome may prove beneficial to understanding aspects of cognition, perception, and other neuropsychological domains in the disease. PD is usually of unilateral onset, providing evidence of intrahemispheric dissociations and an imbalance in the usual relative strengths of the right and left hemispheres. Hence, in order to appreciate the neuropsychology of PD, it is important to apply to this disease our understanding of hemispheric lateralization effects and within-hemisphere circuitry from brainstem to higher-order association cortex. The focus of this review is on the relevance of PD-related disconnections among subcortical and cortical structures to cognition, perception, emotion, and associated brainstem-based domains such as sleep and mood disturbance. Besides providing information on disease characteristics, regarding PD as a disconnection syndrome allows us to more completely understand normal brain-behavior relations in general.