Optimizing levodopa therapy, when and how? Perspectives on the importance of delivery and the potential for an early combination approach

© 2023 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way.Introduction: There is currently a resurgence of levodopa as the initial treatment of choice for most patients with Parkinson's disease, albeit at lower doses than previously used. The addition of adjuvant treatments (including MAO-B inhibitors, COMT inhibitors and dopamine agonists) is an established strategy to reduce motor complications that develop with sustained levodopa therapy. Areas covered: In this narrative review, the authors discuss the evidence underpinning current levodopa optimization strategies, during early disease and once motor complications occur. To support the discussion, the authors performed a broad PubMed search with the terms 'levodopa/L-dopa/L-Dopa, and Parkinson's disease,' restricted to clinical trials. There is now a wealth of evidence that improving levodopa delivery to the brain improves outcomes and we discuss how agents can be combined earlier in the course of disease to leverage the full potential of this strategy. Expert opinion: Levodopa remains the cornerstone of antiparkinsonian therapy. Several promising advances in formulation have been made and include novel extended-release oral drugs as well as non-oral delivery systems. However, evidence has long suggested that anti-parkinsonian medications may be better used in combination earlier in the disease, and consequently patients will benefit from low doses of several agents rather than ever larger levodopa doses.This paper was supported by BIAL, who procured medical writing support but had no other influence on the content of the paper. No author received any remuneration for the preparation of this article.info:eu-repo/semantics/publishedVersio

Defining the Riddle in Order to Solve It:There Is More Than One “Parkinson's Disease”

© 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.Background: More than 200 years after James Parkinsondescribed a clinical syndrome based on his astute observations, Parkinson's disease (PD) has evolved into a complex entity, akin to the heterogeneity of other complex human syndromes of the central nervous system such as dementia, motor neuron disease, multiple sclerosis, and epilepsy. Clinicians, pathologists, and basic science researchers evolved arrange of concepts andcriteria for the clinical, genetic, mechanistic, and neuropathological characterization of what, in their best judgment, constitutes PD. However, these specialists have generated and used criteria that are not necessarily aligned between their different operational definitions, which may hinder progress in solving the riddle of the distinct forms of PD and ultimately how to treat them. Objective: This task force has identified current in consistencies between the definitions of PD and its diverse variants in different domains: clinical criteria, neuropathological classification, genetic subtyping, biomarker signatures, and mechanisms of disease. This initial effort for "defining the riddle" will lay the foundation for future attempts to better define the range of PD and its variants, as has been done and implemented for other heterogeneous neurological syndromes, such as stroke and peripheral neuropathy. We strongly advocate for a more systematic and evidence-based integration of our diverse disciplines by looking at well-defined variants of the syndrome of PD. Conclusion: Accuracy in defining endophenotypes of "typical PD" across these different but interrelated disciplines will enable better definition of variants and their stratification in therapeutic trials, a prerequisite for breakthroughs in the era of precision medicine. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.T.F.O. is supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy—EXC (2067/1-390729940). V.B. is supported by the Stichting Parkinson Fonds (the Netherlands). M.G.S. is supported by the Bhargava Family Research Chair in Neurodegeneration, the Department of Medicine at The Ottawa Hospital and its Foundation. B.M. is supported by The Michael J. Fox Foundation for PD Research, DFG, EU (Horizon 2020), the National Parkinson's Foundation, Parkinson Fonds Deutschland, and the Deutsche Parkinson Vereinigung. L.S. and T.F.O. were supported by IMPRiND and EU (Horizon 2020). H.S. was supported by the Advanced ERC program, The Michael J. Fox foundation, and the Israel Science Fund. We thank Dr. J.P. Vonsattel, Columbia University, for providing the images for Figure 2. Open Access funding enabled and organized by Projekt DEAL.info:eu-repo/semantics/publishedVersio

Influence of Age, Circadian and Homeostatic Processes on Inhibitory Motor Control: A Go/Nogo Task Study

INTRODUCTION: The contribution of circadian system and sleep pressure influences on executive performance as a function of age has never been studied. The aim of our study was to determine the age-related evolution of inhibitory motor control (i.e., ability to suppress a prepotent motor response) and sustained attention under controlled high or low sleep pressure conditions. METHODS: 14 healthy young males (mean age = 23 ± 2.7; 20-29 years) and 11 healthy older males (mean age = 68 ± 1.4; 66-70 years) were recruited. The volunteers were placed for 40 hours in "constant routine". In the "Sleep Deprivation SD" condition, the volunteer was kept awake for 40 hours to obtain a high sleep pressure condition interacting with the circadian process. In the "NAP" condition, the volunteer adopted a short wake/sleep cycle (150/75 min) resulting in a low sleep pressure condition to counteract the homeostatic pressure and investigate the circadian process. Performances were evaluated by a simple reaction time task and a Go/Nogo task repeated every 3H45. RESULTS: In the SD condition, inhibitory motor control (i.e., ability to inhibit an inappropriate response) was impaired by extended wakefulness equally in both age groups (P<.01). Sustained attention (i.e. ability to respond accurately to appropriate stimuli) on the executive task decreased under sleep deprivation in both groups, and even more in young participants (P<.05). In the NAP condition, age did not influence the time course of inhibitory motor control or sustained attention. In the SD and NAP conditions, older participants had a less fluctuating reaction time performance across time of day than young participants (P<.001). CONCLUSION: Aging could be a protective factor against the effects of extended wakefulness especially on sustained attention failures due to an attenuation of sleep pressure with duration of time awake

PTPA variants and impaired PP2A activity in early-onset parkinsonism with intellectual disability

The protein phosphatase 2A complex (PP2A), the major Ser/Thr phosphatase in the brain, is involved in a number of signalling pathways and functions, including the regulation of crucial proteins for neurodegeneration, such as alpha-synuclein, tau and LRRK2. Here, we report the identification of variants in the PTPA/PPP2R4 gene, encoding a major PP2A activator, in two families with early-onset parkinsonism and intellectual disability. We carried out clinical studies and genetic analyses, including genome-wide linkage analysis, whole-exome sequencing, and Sanger sequencing of candidate variants. We next performed functional studies on the disease-associated variants in cultured cells and knock-down of ptpa in Drosophila melanogaster. We first identified a homozygous PTPA variant, c.893T&gt;G (p.Met298Arg), in patients from a South African family with early-onset parkinsonism and intellectual disability. Screening of a large series of additional families yielded a second homozygous variant, c.512C&gt;A (p.Ala171Asp), in a Libyan family with a similar phenotype. Both variants co-segregate with disease in the respective families. The affected subjects display juvenile-onset parkinsonism and intellectual disability. The motor symptoms were responsive to treatment with levodopa and deep brain stimulation of the subthalamic nucleus. In overexpression studies, both the PTPA p.Ala171Asp and p.Met298Arg variants were associated with decreased PTPA RNA stability and decreased PTPA protein levels; the p.Ala171Asp variant additionally displayed decreased PTPA protein stability. Crucially, expression of both variants was associated with decreased PP2A complex levels and impaired PP2A phosphatase activation. PTPA orthologue knock-down in Drosophila neurons induced a significant impairment of locomotion in the climbing test. This defect was age-dependent and fully reversed by L-DOPA treatment. We conclude that bi-allelic missense PTPA variants associated with impaired activation of the PP2A phosphatase cause autosomal recessive early-onset parkinsonism with intellectual disability. Our findings might also provide new insights for understanding the role of the PP2A complex in the pathogenesis of more common forms of neurodegeneration.</p

Neurofilament light levels predict clinical progression and death in multiple system atrophy

Disease-modifying treatments are currently being trialed in multiple system atrophy (MSA). Approaches based solely on clinical measures are challenged by heterogeneity of phenotype and pathogenic complexity. Neurofilament light chain protein has been explored as a reliable biomarker in several neurodegenerative disorders but data in multiple system atrophy have been limited. Therefore, neurofilament light chain is not yet routinely used as an outcome measure in MSA. We aimed to comprehensively investigate the role and dynamics of neurofilament light chain in multiple system atrophy combined with cross-sectional and longitudinal clinical and imaging scales and for subject trial selection. In this cohort study we recruited cross-sectional and longitudinal cases in multicentre European set-up. Plasma and cerebrospinal fluid neurofilament light chain concentrations were measured at baseline from 212 multiple system atrophy cases, annually for a mean period of 2 years in 44 multiple system atrophy patients in conjunction with clinical, neuropsychological and MRI brain assessments. Baseline neurofilament light chain characteristics were compared between groups. Cox regression was used to assess survival; ROC analysis to assess the ability of neurofilament light chain to distinguish between multiple system atrophy patients and healthy controls. Multivariate linear mixed effects models were used to analyse longitudinal neurofilament light chain changes and correlated with clinical and imaging parameters. Polynomial models were used to determine the differential trajectories of neurofilament light chain in multiple system atrophy. We estimated sample sizes for trials aiming to decrease NfL levels. We show that in multiple system atrophy, baseline plasma neurofilament light chain levels were better predictors of clinical progression, survival, and degree of brain atrophy than the NfL rate of change. Comparative analysis of multiple system atrophy progression over the course of disease, using plasma neurofilament light chain and clinical rating scales, indicated that neurofilament light chain levels rise as the motor symptoms progress, followed by deceleration in advanced stages. Sample size prediction suggested that significantly lower trial participant numbers would be needed to demonstrate treatment effects when incorporating plasma neurofilament light chain values into multiple system atrophy clinical trials in comparison to clinical measures alone. In conclusion, neurofilament light chain correlates with clinical disease severity, progression, and prognosis in multiple system atrophy. Combined with clinical and imaging analysis, neurofilament light chain can inform patient stratification and serve as a reliable biomarker of treatment response in future multiple system atrophy trials of putative disease-modifying agents.European Union’s Horizon 2020 research and innovation programm

The "long and winding road" of the disease-modifying effects of levodopa has not ended yet

© 2019 International Parkinson and Movement Disorder SocietyLevodopa has long been the mainstay of Parkinson's disease (PD) pharmacological therapy. Upon its introduction, symptom relief was markedly evident, and hope arose on the potential of effect on disease progression. In fact, James Parkinson did remark that there appeared “to be sufficient reason for hoping that some remedial process may ere long be discovered, by which, at least, the progress of the disease may be stopped.”2 Unfortunately, despite recent advances,3 after 2 centuries of effort and hundreds of trials evaluating dozens of different drugs, we are still to conclusively prove a “neuroprotective” or “disease-modifying” effect of any pharmacological treatment for PD.info:eu-repo/semantics/publishedVersio

Opicapone for the management of end-of-dose motor fluctuations in patients with Parkinson's disease treated with L-DOPA

INTRODUCTION: Opicapone is a third generation, highly potent and effective catechol O‑methyltransferase (COMT) inhibitor that optimizes the pharmacokinetics and bioavailability of L-DOPA therapy. AREAS COVERED: In this review, the authors describe the preclinical and clinical development of opicapone. In PD patients with motor fluctuations, once daily opicapone administration was well-tolerated and consistently reduced OFF-time and increased ON-time without increasing the frequency of troublesome dyskinesia, and these benefits were maintained over at least a year of continued open-label therapy. EXPERT COMMENTARY: With its convenient once-daily regimen, adjunct opicapone should be considered as an effective option for use in L-DOPA treated PD patients experiencing motor fluctuations