ArticleMovement disorders : official journal of the Movement Disorder Society2020
Tryptophan Metabolites Are Associated With Symptoms and Nigral Pathology in Parkinson's Disease.
Article in Movement disorders : official journal of the Movement Disorder Society, 2020. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 76 papers, 2 of them syntheses that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
76 citing papers in PubMed, 2 syntheses or guidelines pooled it, 119 citations in OpenAlex.
- NADFrontiers in neurology · 2026Pooled it
- Dynamic changes in metabolites of the kynurenine pathway in Alzheimer's disease, Parkinson's disease, and Huntington's disease: A systematic Review and meta-analysis.Frontiers in immunology · 2022Pooled it
- Impact of 12 Weeks of Vitamin DNutrients · 2023Trial
- Acute administration of ibuprofen increases serum concentration of the neuroprotective kynurenine pathway metabolite, kynurenic acid: a pilot randomized, placebo-controlled, crossover study.Psychopharmacology · 2022Trial
- Cellular and systemic modifiers of alpha-synuclein proteostasis.Philosophical transactions of the Royal Society of London. Series B, Biological sciences · 2026Review
- Stress and Parkinson's disease: from dysfunctional detection to impaired handling: a narrative review.Journal of neural transmission (Vienna, Austria : 1996) · 2026Review
- Tryptophan Metabolism in Digestive and Extra-Digestive Diseases: Mechanisms, Clinical Implications, and Therapeutic Perspectives.Nutrients · 2026Review
- Bidirectional Mechanisms Linking Circadian Rhythm Disruption and Parkinson's Disease: Chronobiomarkers and Therapeutic Implications.International journal of molecular sciences · 2026Review
- The Kynurenine Pathway: Unraveling Its Role in Neurological Disorders via Mammalian Cellular Models.International journal of molecular sciences · 2026Review
- Article
- Targeted metabolomics to assess positive effects of empagliflozin in a Parkinson's disease model: focused on the kynurenine pathway and oxidative stress.Scientific reports · 2026Article
- Gut-Brain Signaling in Parkinson's Disease: A Narrative Review.International journal of molecular sciences · 2026Review
- Peripheral immunochemical considerations in Parkinson disease: sources, targets and crosstalk mechanisms.Journal of translational medicine · 2026Review
- Periodontal inflammation and tryptophan-kynurenine metabolism in Parkinson's disease.Clinical oral investigations · 2026Article
- Molecular mechanisms and therapeutic potential of tryptophan metabolism in gut-brain signaling transduction: a narrative review.Journal of neuroinflammation · 2026Review
- Serotonin, Kynurenine, and Indole Pathways of Tryptophan Metabolism in Humans in Health and Disease.Nutrients · 2026Review
- Tracing neuroinflammation in neurodegeneration: insights from a scoping review on biofluid biomarkers.Brain communications · 2026Review
- Kynurenine pathway in Parkinson's disease: pathophysiological roles and therapeutic interventions.Inflammopharmacology · 2026Review
- Metabolomic profiles of depression in Parkinson's disease patients.NPJ Parkinson's disease · 2025Article
- Interactions between gut microbiota and parkinson's disease: the role of tryptophan metabolism.Cell communication and signaling : CCS · 2025Review
16 more citing papers are in PubMed but not listed here.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
11 authors at 3 institutions in 1 country.
Funding
Abstract
backgroundThe objective of this study was to determine whether neurotoxic kynurenine metabolites, induced by inflammation, in plasma and cerebrospinal fluid (CSF) are associated with symptom severity and nigral pathology in Parkinson's disease (PD).
methodsClinical and MRI data were obtained from 97 PD and 89 controls. We used ultra-performance liquid chromatography to quantify kynurenine metabolites and high-sensitivity multiplex assays to quantify inflammation in plasma and CSF. We evaluated group-wise differences as well as associations between the biomarkers, motor and nonmotor symptoms, and nigral R2* (MRI metric reflecting iron content).
resultsPD subjects had >100% higher 3-hydroxykynurenine and 14% lower 3-hydroxyanthranilic acid in plasma. The 3-HK in plasma was closely associated with both symptom severity and disease duration. PD subjects also had 23% lower kynurenic acid in the CSF. Higher CSF levels of the excitotoxin quinolinic acid were associated with more severe symptoms, whereas lower levels of the neuroprotective kynurenic acid were linked to olfactory deficits. An elevated quinolinic acid/picolinic acid ratio in the CSF correlated with higher R2* values in the substantia nigra in the entire cohort. Plasma C-reactive protein and serum amyloid alpha were associated with signs of increased kynurenine pathway activity in the CSF of PD patients, but not in controls.
conclusionsIn PD, the kynurenine pathway metabolite levels are altered in both the periphery and the central nervous system, and these changes are associated with symptom severity. Replication studies are warranted in other cohorts, and these can also explore if kynurenine metabolites might be PD biomarkers and/or are involved in PD pathogenesis. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.