Background: To compare drug regimens across clinical trials in Parkinson's disease (PD) conversion formulae between antiparkinsonian drugs have been developed. These are reported in relation to levodopa as the benchmark drug in PD pharmacotherapy as ‘levodopa equivalent dose’ (LED). Currently, the LED conversion formulae proposed in 2010 by Tomlinson et al. based on a systematic review are predominantly used. However, new drugs with established and novel mechanisms of action and novel formulations of longstanding drugs have been developed since 2010. Therefore, consensus proposals for updated LED conversion formulae are needed.Objectives: To update LED conversion formulae based on a systematic review.Methods: The MEDLINE, CENTRAL, and Embase databases were searched from January 2010 to July 2021. Additionally, in a standardized process according to the GRADE grid method, consensus proposals were issued for drugs with scarce data on levodopa dose equivalency.Results: The systematic database search yielded 3076 articles of which 682 were eligible for inclusion in the systematic review. Based on these data and the standardized consensus process, we present proposals for LED conversion formulae for a wide range of drugs that are currently available for the pharmacotherapy of PD or are expected to be introduced soon.Conclusions: The LED conversion formulae issued in this Position Paper will serve as a research tool to compare the equivalence of antiparkinsonian medication across PD study cohorts and facilitate research on the clinical efficacy of pharmacological and surgical treatments as well as other non‐pharmacological interventions in PD. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

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Background: The objective of this study was to assess neurofilament light chain as a Parkinson's disease biomarker.Methods: We quantified neurofilament light chain in 2 independent cohorts: (1) longitudinal cerebrospinal fluid samples from the longitudinal de novo Parkinson's disease cohort and (2) a large longitudinal cohort with serum samples from Parkinson's disease, other cognate/neurodegenerative disorders, healthy controls, prodromal conditions, and mutation carriers.Results: In the Parkinson's Progression Marker Initiative cohort, mean baseline serum neurofilament light chain was higher in Parkinson's disease patients (13 ± 7.2 pg/mL) than in controls (12 ± 6.7 pg/mL), P = 0.0336. Serum neurofilament light chain increased longitudinally in Parkinson's disease patients versus controls (P < 0.01). Motor scores were positively associated with neurofilament light chain, whereas some cognitive scores showed a negative association.Conclusions: Neurofilament light chain in serum samples is increased in Parkinson's disease patients versus healthy controls, increases over time and with age, and correlates with clinical measures of Parkinson's disease severity. Although the specificity of neurofilament light chain for Parkinson's disease is low, it is the first blood‐based biomarker candidate that could support disease stratification of Parkinson's disease versus other cognate/neurodegenerative disorders, track clinical progression, and possibly assess responsiveness to neuroprotective treatments. However, use of neurofilament light chain as a biomarker of response to neuroprotective interventions remains to be assessed. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Parkinson’s disease is increasingly prevalent. It progresses from the pre-motor stage (characterised by non-motor symptoms like REM sleep behaviour disorder), to the disabling motor stage. We need objective biomarkers for early/pre-motor disease stages to be able to intervene and slow the underlying neurodegenerative process. Here, we validate a targeted multiplexed mass spectrometry assay for blood samples from recently diagnosed motor Parkinson’s patients (n = 99), pre-motor individuals with isolated REM sleep behaviour disorder (two cohorts: n = 18 and n = 54 longitudinally), and healthy controls (n = 36). Our machine-learning model accurately identifies all Parkinson patients and classifies 79% of the pre-motor individuals up to 7 years before motor onset by analysing the expression of eight proteins—Granulin precursor, Mannan-binding-lectin-serine-peptidase-2, Endoplasmatic-reticulum-chaperone-BiP, Prostaglaindin-H2-D-isomaerase, Interceullular-adhesion-molecule-1, Complement C3, Dickkopf-WNT-signalling pathway-inhibitor-3, and Plasma-protease-C1-inhibitor. Many of these biomarkers correlate with symptom severity. This specific blood panel indicates molecular events in early stages and could help identify at-risk participants for clinical trials aimed at slowing/preventing motor Parkinson’s disease.

D-Cycloserine, known from tuberculosis therapy, has been widely introduced to neuropsychiatric studies, since its central active mechanism as a partial NMDA-agonist has been found. In this review, we evaluate its therapeutic potential in neuropsychological disorders and discuss its pitfalls in terms of dosing and application frequency as well as its safety in low-dose therapy. Therefore, we identified 91 clinical trials by performing a Medline search. We demonstrate in part preliminary but increasing evidence that D-cycloserine may be effective in various psychiatric diseases, including schizophrenia, anxiety disorders, addiction, eating disorders, major depression, and autism as well as in neurological diseases, including dementia, Alzheimer’s disease, and spinocerebellar degeneration. D-Cycloserine in low-dose therapy is safe, but there is still a need for new drugs with higher specificity to the different N-methyl-D-aspartate-receptor subunits.

Background: Misfolded α‐synuclein (αSyn) aggregates (αSyn‐seeds) in cerebrospinal fluid (CSF) are biomarkers for synucleinopathies such as Parkinson's disease (PD). αSyn‐seeds have been detected in prodromal cases with isolated rapid eye movement sleep behavior disorder (iRBD).Objectives: The objective of this study was to determine the accuracy of the αSyn–seed amplification assay (αS‐SAA) in a comprehensively characterized cohort with a high proportion of PD and iRBD CSF samples collected at baseline.Methods: We used a high‐throughput αS‐SAA to analyze 233 blinded CSF samples from 206 participants of the DeNovo Parkinson Cohort (DeNoPa) (113 de novo PD, 64 healthy controls, 29 iRBD confirmed by video polysomnography). Results were compared with the final diagnosis, which was determined after up to 10 years of longitudinal clinical evaluations, including dopamine‐transporter–single‐photon emission computed tomography (DAT‐SPECT) at baseline, CSF proteins, Movement Disorder Society–Unified Parkinson's Disease Rating Scale, and various cognitive and nonmotor scales.Results: αS‐SAA detected αSyn‐seeds in baseline PD‐CSF with 98% accuracy. αSyn‐seeds were detected in 93% of the iRBD cases. αS‐SAA results showed higher agreement with the final than the initial diagnosis, as 14 patients were rediagnosed as non‐αSyn aggregation disorder. For synucleinopathies, αS‐SAA showed higher concordance with the final diagnosis than DAT‐SPECT. Statistically significant correlations were found between assay parameters and disease progression.Conclusions: Our results confirm αS‐SAA accuracy at the first clinical evaluation when a definite diagnosis is most consequential. αS‐SAA conditions reported here are highly sensitive, enabling the detection of αSyn‐seeds in CSF from iRBD just months after the first symptoms, suggesting that αSyn‐seeds are present in the very early prodromal phase of synucleinopathies. Therefore, αSyn‐seeds are clear risk markers for synuclein‐related disorders, but not for time of phenoconversion. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.