Neuroimaging of Parkinson's disease by quantitative susceptibility mapping

High resolution multi-parametric probabilistic in vivo atlas of dorsolateral nigral hyperintensity via 7 T MRI

The role of Nigrosome 1 (N1) in neurodegeneration and motor disorders, particularly in Parkinson's disease (PD), is increasingly recognized. The study of this region using quantitative measures, such as iron quantification through Quantitative Susceptibility Mapping (QSM), can provide enlightening insights into some pathological features of these diseases representing important biomarkers. However, the small size and the vanishing contrast with respect to the surrounding substantia nigra in PD patients make the segmentation of N1 challenging. For this reason, we provide a probabilistic atlas of the N1 portion corresponding to the swallow-tail hyperintensity, hereafter referred to as the Dorsolateral Nigral Hyperintensity (DNH), created on a high-resolution multi-parametric template from T1-weighted, T2*-weighted, and QSM images acquired in vivo at 7 T. The atlas also includes quantitative T2* and R2* templates and is provided in the MNI standard space. It aims to facilitate the study of N1, avoiding operator-dependent biases in segmentations, and allowing the standardisation of the quantitative assessment.

Multiparametric analysis based on 18F-AV133 PET/MR imaging for clinical application in Parkinson's disease

OBJECTIVE

The progressive loss of dopaminergic neurons and abnormal iron deposition in the central nervous system (CNS) are key pathogenic mechanisms of Parkinson's disease (PD). This study aimed to explore the relationship between iron deposition in specific CNS regions and striatal dysfunction using 18F-AV133 PET/MR imaging.

METHODS

Based on the Hoehn-Yahr stage, 24 patients with early-stage PD (EPD, stage ≤ 2.5), 17 patients with late-stage PD (LPD, stage ≥ 3), and 30 healthy controls (HCs) were recruited for scale evaluation. The specific uptake ratio (SUR) of striatal subregions was calculated using the occipital cortex as the reference region. Quantitative Susceptibility Mapping (QSM) values of major subcortical nuclei were derived through QSM imaging. Spearman correlation analysis was conducted to assess the relationships between SUR in striatal subregions, QSM values in nuclear groups, and PD clinical symptoms, as well as the correlation between SUR and QSM values.

RESULTS

Compared to HC, EPD and LPD patients showed significantly reduced VMAT2 distribution in the bilateral caudate nuclei and anteroposterior putamen, particularly in the contralateral posterior putamen. In PD patients, the SUR of striatal subregions and QSM values of the substantia nigra (SN), globus pallidus (GP), and external segment of the GP (GPe) were significantly correlated with disease duration, H&Y stage, UPDRS III score, and NMSS score. Moreover, SUR of striatal subregions was negatively correlated with QSM values in the SN, GP, internal segment of the GP (GPi), and GPe.

CONCLUSION

Multi-parameter analysis revealed a region-specific correlation between striatal dysfunction and iron deposition in PD, offering new avenues to elucidate the underlying mechanisms of the disease.

Excessive iron accumulation in the striatum associated with addictive behaviors of medication-overuse headache: a prospective study

BACKGROUND

Abnormal iron deposition may be a biomarker for a disrupted central antinociceptive neuronal network, and the relationship between iron deposition and the pathophysiological mechanisms of chronic migraine (CM) with medication overuse (MOH) remains unclear. We investigated iron deposition in the deep gray matter (DGM) of the brain in CM patients with and without MOH using quantitative susceptibility mapping (QSM).

METHODS

Forty-eight healthy controls (HCs) and 69 CM patients (36 with MOH; 33 without MOH) were recruited. QSM data were acquired using a 3.0 T Magnetic resonance imaging (MRI). Regions of interest (ROI) in the DGM, including the bilateral caudate, putamen, globus pallidus (GP), hippocampus, nucleus accumbens, and amygdala, were segmented from the T1-weighted images (T1WI) of the whole brain of each individual patient using FreeSurfer. QSM images were registered to T1WI. QSM values within each ROI were extracted and compared between CM and HCs, as well as between CM with MOH and CM without MOH. Correlations between QSM values and clinical assessment scale scores were calculated. Receiver operating characteristic (ROC) analysis was used to assess the diagnostic performance of QSM values in these DGM for detecting CM and CM with MOH.

RESULTS

Compared to HCs, CM patients exhibited increased iron deposition in the caudate (p = 0.013) and putamen (p < 0.001). In the CM without MOH group, headache duration correlated positively with iron deposition in the caudate (r = 0.502, p = 0.010) and putamen (r = 0.514, p = 0.009). CM with MOH patients showed greater iron deposition in the caudate (p < 0.001), putamen (p < 0.001), and GP (p = 0.049) than those without MOH, with medication use frequency correlating positively with iron deposition in the caudate (r = 0.427, p = 0.023) and putamen (r = 0.445, p = 0.018). ROC curve analysis indicated that the caudate (AUC = 0.736) and putamen (AUC = 0.729) exhibited high sensitivity and specificity in diagnosing CM with MOH.

CONCLUSIONS

CM patients with MOH had excessive iron deposition in basal ganglia regions, including the caudate, putamen, and GP, which may be related to the medication overuse behavior. Iron deposition in the caudate and putamen may be a potential biomarker for CM with MOH. These findings provide insight into the common pathophysiological mechanisms underlying MOH and potential addiction.

Exploring the Application Potential of α-Synuclein Molecular Probes in Early Diagnosis of Parkinson's Disease: Focus on Imaging Methods

This review aims to explore the potential application of α-synuclein (α-syn) molecular probes in the early diagnosis of Parkinson's disease (PD), particularly through systematic evaluation using medical imaging methods. In recent years, The abnormal aggregation of α-syn within the central nervous system is now recognized as a central driver of PD pathophysiology, solidifying its role as a critical diagnostic and prognostic biomarker. Early diagnosis of PD is critical for enabling precision therapeutic interventions and mitigating neurodegenerative progression, thereby enhancing long-term functional outcomes and the quality of life. However, challenges remain in clinical practice, particularly concerning the late timing of diagnosis and the lack of specific biomarkers. By analyzing the existing literature, we will assess the effectiveness of different imaging techniques combined with α-syn probes and discuss their advantages and limitations in clinical applications. These imaging methods can provide visualization of early pathological changes, helping to improve the recognition rate of PD. Finally, we emphasize the importance of future research to explore new molecular probes and imaging technologies that can improve early diagnosis rates and treatment outcomes for PD.

Preparing for Parkinson's disease prevention trials: Current progress and future directions

In recent decades, numerous clinical trials have aimed to delay or prevent Parkinson's disease (PD) progression. Despite the theoretical promise and encouraging preclinical data, none have shown clear efficacy in slowing or preventing PD progression, related to several key limitations. Conventional motor and non-motor scales often fall short in detecting early disease changes, while the heterogeneity of PD phenotypes complicates treatment efficacy. The timing of interventions is also critical, as most trials target patients already in advanced stages of neurodegeneration. A deeper understanding of the preclinical phase and the emergence of new pathological frameworks have shifted the focus toward preventing the onset of clinical PD. Recent advances in biomarker research, including tissue, fluid, and imaging markers, are poised to transform PD research by improving patient selection, stratification, and disease progression monitoring. New biologically grounded frameworks for classifying synucleinopathies aim to distinguish biological subtypes from clinical phenotypes, enabling more targeted prevention trials. Successful PD prevention trials will require early enrollment of individuals at the highest risk, employing low-risk personalized interventions, with biomarkers or sensitive clinical markers as endpoints. Early involvement of key stakeholders will be essential to ensure that trials are timely, ethically sound, and aligned with the needs of the PD community.

Identifying brain degeneration patterns in early-stage Parkinson's disease: a multimodal MRI study

Parkinson's disease (PD) is a highly heterogeneous neurodegenerative disorder. This study aimed to identify different patterns of early brain degeneration in PD patients and investigate their clinical relevance. 179 early-stage PD patients and 115 healthy controls were included. We assessed cortical morphology, white matter microstructure, and subcortical iron metabolism using multimodal magnetic resonance imaging and employed clustering techniques to identify subtypes. Two subtypes were identified: the early-deterioration subtype, characterized by fronto-temporal atrophy, parietal thickening, widespread reductions in fractional anisotropy (FA) values, and increased subcortical iron content, which exhibited more severe baseline symptoms and a trend of faster memory decline; and the early-compensatory subtype, characterized by rostral middle frontal atrophy, parietal-occipital thickening, increased FA values, and normal iron content, which exhibited milder symptoms initially but experienced faster progression of both motor and non-motor symptoms. These discoveries provided new insights into disease heterogeneity and facilitated the exploration of early neurodegenerative mechanisms.

Potential Separation of Multiple System Atrophy and Parkinson's Disease by Susceptibility-derived Components

BACKGROUND

Substantial evidence emphasizes the dysregulation of iron homeostasis, demyelination and oxidative stress in the neurodegenerative process of multiple system atrophy (MSA) and Parkinson's disease (PD), although its clinical implications remain unclear. Recent MRI post-processing techniques leveraging magnetic susceptibility properties provide a noninvasive means to characterize iron, myelin content and oxygen metabolism alterations. This study aims to investigate subcortical alterations of susceptibility-derived metrics in these two synucleinopathies.

METHODS

A cohort comprising 180 patients (122 with PD and 58 with MSA) and 77 healthy controls (HCs) underwent clinical evaluation and multi-echo gradient echo MRI scans. Susceptibility source separation, susceptibility-based oxygen extraction fraction (OEF) mapping and semiautomatic subcortical nuclei segmentation were utilized to derive parametric values of deep gray matter in all subjects.

RESULTS

MSA patients showed markedly elevated paramagnetic susceptibility values in the putamen, globus pallidus (GP) and thalamus; increased diamagnetic susceptibility values in the putamen and dentate nucleus; and reduced OEF values across all nuclei compared with PD patients and HCs. Whereas PD exhibited increased positive susceptibility values in the substantia nigra and enhancing negative values in the GP, similar to MSA. Notably, age-related reductions in OEF were evident in HCs, which was altered by the MSA pathology. Paramagnetic susceptibility was correlated with disease severity. Moreover, the susceptibility-derived metrics of striatum and midbrain nuclei proved to be effective predictors to distinguish PD from MSA (AUC = 0.833).

CONCLUSION

Susceptibility-derived metrics could detect pathological involvement distinct to each disease, offering significant potential for differentiating between MSA and PD in clinical settings.

Simultaneous Increase of Mean Susceptibility and Mean Kurtosis in the Substantia Nigra as an MRI Neuroimaging Biomarker for Early-Stage Parkinson's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disorder. Early detection is crucial for treatment and slowing disease progression.

HYPOTHESIS

Simultaneous alterations in mean susceptibility (MS) from quantitative susceptibility mapping (QSM) and mean kurtosis (MK) from diffusion kurtosis imaging (DKI) can serve as reliable neuroimaging biomarkers for early-stage PD (ESPD) in the basal ganglia nuclei, including the substantia nigra (SN), putamen (PUT), globus pallidus (GP), and caudate nucleus (CN).

STUDY TYPE

Systematic review and meta-analysis.

POPULATION

One hundred eleven patients diagnosed with ESPD and 81 healthy controls (HCs) were included from four studies that utilized both QSM and DKI in both subject groups.

FIELD STRENGTH/SEQUENCE

Three-dimensional multi-echo gradient echo sequence for QSM and spin echo planar imaging sequence for DKI at 3 Tesla.

ASSESSMENT

A systematic review and meta-analysis using PRISMA guidelines searched PubMed, Web of Science, and Scopus.

STATISTICAL TESTS

Random-effects model, standardized mean difference (SMD) to compare MS and MK between ESPD patients and HCs, I2 statistic for heterogeneity, Newcastle-Ottawa Scale (NOS) for risk of bias, and Egger's test for publication bias. A P-value <0.05 was considered significant.

RESULTS

MS values were significantly higher in SN (SMD 0.72, 95% CI 0.31 to 1.12), PUT (SMD 0.68, 95% CI 0.29 to 1.07), and GP (SMD 0.53, 95% CI 0.19 to 0.87) in ESPD patients compared to HCs. CN did not show a significant difference in MS values (P = 0.15). MK values were significantly higher only in SN (SMD = 0.72, 95% CI 0.16 to 1.27). MK values were not significantly different in PUT (P = 1.00), GP (P = 0.97), and CN (P = 0.59). Studies had high quality (NOS 7-8) and no publication bias (P = 0.967).

DATA CONCLUSION

Simultaneous use of MS and MK may be useful as an early neuroimaging biomarker for ESPD detection and its differentiation from HCs, with significant differences observed in the SN.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 2.

Ferroptosis role in complexity of cell death: unrevealing mechanisms in Parkinson's disease and therapeutic approaches

Parkinson's disease (PD), a common neurodegenerative disorder, is characterized by progressive loss of dopaminergic neurons, and accumulation of α-synuclein in the substantial nigra. Emerging evidence identifies ferroptosis as a regulated iron-dependent cell death mechanism marked by excessive lipid peroxidation (LPO) as a key contributor to PD pathogenesis. Ferroptosis is intertwined with critical disease processes such as aggregation of α-synuclein protein, oxidative stress generation, mitochondrial alteration, iron homeostasis dysregulation, and neuroinflammation. This mechanism disrupts cellular homeostasis by impairing iron metabolism and antioxidant pathways like the xc-/glutathione/GPX4 axis and the CoQ10 pathway. This review consolidates current advancements in understanding ferroptosis in these mechanisms, increasing interest in contribution to PD pathology. In addition, it explores the latest developments in ferroptosis-targeting pharmacological agents, including their application in the preclinical and clinical study, and highlights their potential to revolutionize PD management. Unraveling the interplay between ferroptosis and PD offers a transformative perspective, paving the way for innovative therapies to combat this debilitating disease condition.

Comparing repeatability metrics for quantitative susceptibility mapping in the head and neck

OBJECTIVE

Quantitative susceptibility mapping (QSM) is a technique that has been demonstrated to be highly repeatable in the brain. As QSM is applied to other parts of the body, it is necessary to investigate metrics for quantifying repeatability, to enable optimization of repeatable QSM reconstruction pipelines beyond the brain.

MATERIALS AND METHODS

MRI data were acquired in the head and neck (HN) region in ten healthy volunteers, who underwent six acquisitions across two sessions. QSMs were reconstructed using six representative state-of-the-art techniques. Repeatability of the susceptibility values was compared using voxel-wise metrics (normalized root mean squared error and XSIM) and ROI-based metrics (within-subject and between-subject standard deviation, coefficient of variation (CV), intraclass correlation coefficient (ICC)).

RESULTS

Both within-subject and between-subject variations were smaller than the variation between QSM dipole inversion methods, in most ROIs. autoNDI produced the most repeatable susceptibility values, with ICC > 0.75 in three of six HN ROIs with an average ICC of 0.66 across all ROIs. Joint consideration of standard deviation and ICC offered the best metric of repeatability for comparisons between QSM methods, given typical distributions of positive and negative QSM values.

DISCUSSION

Repeatability of QSM in the HN region is highly dependent on the dipole inversion method chosen, but the most repeatable methods (autoNDI, QSMnet, TFI) are only moderately repeatable in most HN ROIs.

Neurotransmitter imbalance, glutathione depletion and concomitant susceptibility increase in Parkinson's disease

BACKGROUND

Emerging insights into the pathophysiology of Parkinson's disease (PD) underscore the involvement of dysregulated neurotransmission, iron accumulation and oxidative stress. Nonetheless, the excitatory and inhibitory neurometabolites, the antioxidant glutathione (GSH), and magnetic susceptibility are seldom studied together in the clinical PD literature.

METHODS

We acquired MEGA-PRESS and multi-echo gradient echo sequences from 60 PD patients and 47 healthy controls (HCs). Magnetic resonance spectroscopy voxels were respectively positioned in the midbrain to quantify neurotransmitter including γ-aminobutyric acid (GABA) and glutamate plus glutamine, and in the left striatum to estimate GSH levels. Group differences in metabolite levels normalized to total creatine (Cr) and their clinical relevance were determined. Furthermore, relationships among GSH levels, neurotransmitter estimates and susceptibility values were explored in both PD patients and HCs.

RESULTS

PD patients exhibited reduced midbrain GABA levels (P = 0.034, PFDR = 0.136), diminished GSH in the left striatum (P = 0.032, PFDR = 0.096), and increased susceptibility values in the substantia nigra (PFDR < 0.001). Mesencephalic choline levels were correlated with the severity of rapid eye movement sleep behavior disorders symptoms, whereas striatal N-acetylaspartate levels were linked to Hoehn-Yahr stage and motor symptom severity. Notably, the disruption of associations between striatal GSH levels and susceptibility values in globus pallidus, as well as midbrain GABA levels, were evident in PD.

CONCLUSIONS

These findings offer compelling evidence for metabolic dysregulation in PD, characterized by a concomitant reduction in GABA and GSH levels, alongside iron deposition.

Multimodal Magnetic Resonance Findings in Parkinson's Disease With "Antecedent Essential Tremor": A Case Series of a Large Kindred

Background

The clinical pictures of essential tremor (ET) and Parkinson's disease (PD) are often quite mimic at the early stage, and longstanding ET may ultimately develop to PD, that is, PD with "antecedent ET". Early diagnosis and differentiation of the two are essential for predicting disease progression and formulating individualized treatment plans. However, current approaches remain challenging. This study aimed at determining the morphological, microstructural and iron-related changes in these patients' brains using multimodal magnetic resonance imaging (MRI).

Methods

We reviewed a kindred with ET and PD with "antecedent ET" recruited at our hospital in May 2023. The clinical characteristics, genetic testing and multimodal MRI data of 16 family members were collected. Multimodal MRI analysis included structural MRI, diffusion tensor imaging (DTI) and tractography, and quantitative susceptibility mapping (QSM).

Results

Two second-generation family members diagnosed PD had ET history before PD performance appeared, five third-generation family members were diagnosed with ET. Fifteen of the 16 cases had missense mutation in the EIF4G1 gene. Temporal and spatial features of morphology and iron deposition in different brain regions were heterogeneous. DTI showed that the cerebello-thalamo-motor cortical network was involved in both ET and PD cases, and the additional nigrostriatal-thalamo-motor cortical network was involved in PD cases.

Conclusion

The combination of morphometric imaging, DTI and QSM could be used as an imaging biomarker for ET and PD diagnosis and could be an effective tool for longitudinal monitoring of disease progression and transformation.

Evolving Landscape of Parkinson's Disease Research: Challenges and Perspectives

Parkinson's disease (PD) is a progressive neurodegenerative disorder that primarily affects movement. It occurs due to a gradual deficit of dopamine-producing brain cells, particularly in the substantia nigra. The precise etiology of PD is not fully understood, but it likely involves a combination of genetic and environmental factors. The therapies available at present alleviate symptoms but do not stop the disease's advancement. Research endeavors are currently directed at inventing disease-controlling therapies that aim at the inherent mechanisms of PD. PD biomarker breakthroughs hold enormous potential: earlier diagnosis, better monitoring, and targeted treatment based on individual response could significantly improve patient outcomes and ease the burden of this disease. PD research is an active and evolving field, focusing on understanding disease mechanisms, identifying biomarkers, developing new treatments, and improving care. In this report, we explore data from the CAS Content Collection to outline the research progress in PD. We analyze the publication landscape to offer perspective into the latest expertise advancements. Key emerging concepts are reviewed and strategies to fight disease evaluated. Pharmacological targets, genetic risk factors, as well as comorbid diseases are explored, and clinical usage of products against PD with their production pipelines and trials for drug repurposing are examined. This review aims to offer a comprehensive overview of the advancing landscape of the current understanding about PD, to define challenges, and to assess growth prospects to stimulate efforts in battling the disease.

Association between deep gray matter iron deposition and clinical symptoms in Parkinson's disease: a quantitative susceptibility mapping study

Purpose

This study aimed to assess the association between motor and non-motor symptoms of Parkinson's disease (PD) and iron accumulation within the deep gray matter of the brain by Quantitative Susceptibility Mapping (QSM).

Methods

Fifty-six PD patients and twenty-nine healthy controls were recruited in this study. According to the Hoehn and Yahr (H-Y) stage score, PD patients were divided into early stage (H-Y ≤ 2) and advanced stage (H-Y > 2) groups. Specifically, the Regions of Interest (ROIs) encompassed the substantia nigra (SN), red nucleus (RN), caudate nucleus (CN), globus pallidus (GP) and putamen (PT). Meanwhile, various rating scales were used to assess the clinical symptoms of PD.

Results

Compared to healthy controls (HCs), PD patients showed a significant increase in magnetic susceptibility values (MSVs) within the SN and GP. Further comparisons indicated that the MSVs of the SN, PT, GP and CN are all higher in advanced stages than in early stages. Significant positive correlations were observed between the MSVs of the SN and scores on the UPDRS-III, HAMA, and HAMD (r = 0.310, p = 0.020; r = 0.273, p = 0.042; r = 0.342, p = 0.010, respectively). Likewise, the MSVs of the GP demonstrated notable correlations with HAMA and HAMD scores (r = 0.275, p = 0.040; r = 0.415, p = 0.001). Additionally, a significant correlation was found between the MSVs of the PT and HAMD scores (r = 0.360, p = 0.006). Furthermore, we identified a significant negative correlation between MMSE scores and the MSVs of both the PT and GP (r = -0.268, p = 0.046; r = -0.305, p = 0.022).

Conclusion

Our study revealed that QSM possesses the capability to serve as a biomarker for PD. Significant correlations were found between clinical features and the iron deposition in the nigrostriatal system.

Acupuncture treatment of restless legs syndrome: a randomized clinical controlled study protocol based on PET-CT and fMRI

Introduction

Restless legs syndrome (RLS) is a sensorimotor disorder of the nervous system that is mainly characterized by nighttime leg discomfort and can be accompanied by significant anxiety, depression, and other mood disorders. RLS seriously affects the quality of life. Clinical studies have confirmed that acupuncture can alleviate the clinical symptoms of RLS. This randomized controlled trial (RCT) aims to investigate the efficacy of acupuncture in the treatment of RLS and further explore the central response mechanism of acupuncture in the treatment of RLS.

Methods and analysis

In this RCT, a total of 124 eligible patients in Shanghai will be randomly assigned to one of the following two groups: treatment group (acupuncture) and control group (sham acupuncture). Treatment will be given three times per week for 4 consecutive weeks. The primary outcome is the International Restless Legs severity rating scale (IRLSS). The secondary outcomes are the RLS-Quality of Life (RLSQoL), the Insomnia Severity Index (ISI), Pittsburgh Sleep Quality Index (PSQI), the Hamilton Depression Scale (HAMD), and the Hamilton Anxiety Scale (HAMA). The objective evaluation tools will be polysomnography, positron emission tomography-computed tomography (PET-CT), and functional magnetic resonance imaging (fMRI) of the brain. All adverse effects will be assessed by the Treatment Emergent Symptom Scale. Outcomes will be evaluated at baseline (1 week before the first intervention), during the intervention (the second week of the intervention), after the intervention (at the end of the intervention), at 1-month follow-up, and at 3-month follow-up.

Ethics and dissemination

The trial has been approved by the Ethics Committee of Yueyang Hospital of Integrated Traditional Chinese and Western Medicine (no. 2022-061). Written informed consent will be obtained from all participants. The results of this study will be published in peer-reviewed journals or presented at academic conferences.

Clinical trial registration

https://www.chictr.org.cn/, identifier ChiCTR2000037287.

Parkinson's Disease: Biomarkers for Diagnosis and Disease Progression

Parkinson's disease (PD) is a progressive neurological disease that causes both motor and nonmotor symptoms. While our understanding of putative mechanisms has advanced significantly, it remains challenging to verify biomarkers with sufficient evidence for regular clinical use. Clinical symptoms are the primary basis for diagnosing the disease, which can be mild in the early stages and overlap with other neurological disorders. As a result, clinical testing and medical records are mostly relied upon for diagnosis, posing substantial challenges during both the initial diagnosis and the continuous disease monitoring. Recent biochemical, neuroimaging, and genetic biomarkers have helped us understand the pathophysiology of Parkinson's disease. This comprehensive study focuses on these biomarkers, which were chosen based on their relevance, methodological excellence, and contribution to the field. Biochemical biomarkers, including α-synuclein and glial fibrillary acidic protein (GFAP), can predict disease severity and progression. The dopaminergic system is widely used as a neuroimaging biomarker to diagnose PD. Numerous genes and genome wide association study (GWAS) sites have been related to the development of PD. Recent research on the SNCA gene and leucine-rich repeat protein kinase 2 (LRRK2) has shown promising results. By evaluating current studies, this review intends to uncover gaps in biomarker validation and use, while also highlighting promising improvements. It emphasizes the need for dependable and reproducible indicators in improving PD diagnosis and prognosis. These biomarkers may open up new avenues for early diagnosis, disease progression tracking, and the development of personalized treatment programs.

Advances in understanding biomarkers and treating neurological diseases - Role of the cerebellar dysfunction and emerging therapies

Cerebellar dysfunction is increasingly recognized as a critical factor in various neurological diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). Research has revealed distinct cerebellar atrophy patterns in conditions such as AD and multiple system atrophy, and studies in mice have highlighted its impact on motor control and cognitive functions. Emerging research into autism spectrum disorder (ASD) has identified key targets, such as elevated levels of chemokine receptors and ZIC family genes. Biomarkers, including cerebrospinal fluid (CSF), genetic markers, and advances in AI and bioinformatics, are enhancing early diagnosis and personalized treatment across neurodegenerative disorders. Notable advancements include improved diagnostic tools, gene therapy, and novel clinical trials. Despite progress, challenges such as the bloodbrain barrier and neuroinflammation persist. Current therapies for AD, PD, HD, and ALS, including antisense oligonucleotides and stem cell treatments, show promise but require further investigation. A comprehensive approach that integrates diagnostic methods and innovative therapies is essential for effective management and improved patient outcomes.

Bibliometric analysis of global research trends in magnetic resonance imaging studies of substantia nigra in Parkinson's disease (2001-2024)

Background

Parkinson's disease (PD) is a globally prevalent neurodegenerative disorder, primarily characterized by muscle rigidity, resting tremor, and bradykinesia. The incidence of PD is rapidly escalating worldwide. Numerous studies have been conducted on the application of magnetic resonance imaging (MRI) in investigating the substantia nigra (SN) in PD patients. However, to date, no bibliometric analysis has been performed on this specific research area. Therefore, this study aimed to provide a comprehensive analysis of the current status in MRI research on the SN in PD patients.

Materials and methods

MRI study records related to the SN in PD patients from 2001 to 2024 were searched by using the Web of Science Core Collection (WOSCC) database and then the CiteSpace and VOSviewer were used to conduct bibliometric analysis.

Results

Our analysis found that the number of published articles related studies on MRI of the SN in PD showed an overall upward trend over the past decade, in which Lehericy, Stephane, Du, Guangwei, and Huang, Xuemei are the top three authors with the most articles. Additionally, United States, China and Germany are the main contributors to MRI studies of SN in PD. And Shanghai Jiao Tong University, University of Florida and Seoul National University are the leading institutions in the field. Finally, the keyword analysis showed that the hotspots and trends of research in this field are mainly concentrated in quantitative susceptibility mapping, neuroimaging, and neuromelanin-sensitive MRI.

Conclusion

These analysis identified the most influential authors, institutions, countries and research hotspots in the field of SN-MRI research in PD, which has reference significance for the research interest in this field and provides a new idea for PD prevention.

Quantitative susceptibility mapping of multiple system atrophy and Parkinson's disease correlates with neurotransmitter reference maps

BACKGROUND

Multiple system atrophy (MSA) and Parkinson's disease (PD) are neurodegenerative disorders characterized by α-synuclein pathology, disrupted iron homeostasis and impaired neurochemical transmission. Considering the critical role of iron in neurotransmitter synthesis and transport, our study aims to identify distinct patterns of whole-brain iron accumulation in MSA and PD, and to elucidate the corresponding neurochemical substrates.

METHODS

A total of 122 PD patients, 58 MSA patients and 78 age-, sex-matched health controls underwent multi-echo gradient echo sequences and neurological evaluations. We conducted voxel-wise and regional analyses using quantitative susceptibility mapping to explore MSA or PD-specific alterations in cortical and subcortical iron concentrations. Spatial correlation approaches were employed to examine the topographical alignment of cortical iron accumulation patterns with normative atlases of neurotransmitter receptor and transporter densities. Furthermore, we assessed the associations between the colocalization strength of neurochemical systems and disease severity.

RESULTS

MSA patients exhibited increased susceptibility in the striatal, midbrain, cerebellar nuclei, as well as the frontal, temporal, occipital lobes, and anterior cingulate gyrus. In contrast, PD patients displayed elevated iron levels in the left inferior occipital gyrus, precentral gyrus, and substantia nigra. The excessive iron accumulation in MSA or PD correlated with the spatial distribution of cholinergic, noradrenaline, glutamate, serotonin, cannabinoids, and opioid neurotransmitters, and the degree of this alignment was related to motor deficits.

CONCLUSIONS

Our findings provide evidence of the interaction between iron accumulation and non-dopamine neurotransmitters in the pathogenesis of MSA and PD, which inspires research on potential targets for pharmacotherapy.

Abnormality in Peripheral and Brain Iron Contents and the Relationship with Grey Matter Volumes in Major Depressive Disorder

Major depressive disorder (MDD) is a prevalent mental illness globally, yet its etiology remains largely elusive. Recent interest in the scientific community has focused on the correlation between the disruption of iron homeostasis and MDD. Prior studies have revealed anomalous levels of iron in both peripheral blood and the brain of MDD patients; however, these findings are not consistent. This study involved 95 MDD patients aged 18-35 and 66 sex- and age-matched healthy controls (HCs) who underwent 3D-T1 and quantitative susceptibility mapping (QSM) sequence scans to assess grey matter volume (GMV) and brain iron concentration, respectively. Plasma ferritin (pF) levels were measured in a subset of 49 MDD individuals and 41 HCs using the Enzyme-linked immunosorbent assay (ELISA), whose blood data were simultaneously collected. We hypothesize that morphological brain changes in MDD patients are related to abnormal regulation of iron levels in the brain and periphery. Multimodal canonical correlation analysis plus joint independent component analysis (MCCA+jICA) algorithm was mainly used to investigate the covariation patterns between the brain iron concentration and GMV. The results of "MCCA+jICA" showed that the QSM values in bilateral globus pallidus and caudate nucleus of MDD patients were lower than HCs. While in the bilateral thalamus and putamen, the QSM values in MDD patients were higher than in HCs. The GMV values of these brain regions showed a significant positive correlation with QSM. The GMV values of bilateral putamen were found to be increased in MDD patients compared with HCs. A small portion of the thalamus showed reduced GMV values in MDD patients compared to HCs. Furthermore, the region of interest (ROI)-based comparison results in the basal ganglia structures align with the outcomes obtained from the "MCCA+jICA" analysis. The ELISA results indicated that the levels of pF in MDD patients were higher than those in HCs. Correlation analysis revealed that the increase in pF was positively correlated with the iron content in the left thalamus. Finally, the covariation patterns obtained from "MCCA+jICA" analysis as classification features effectively differentiated MDD patients from HCs in the support vector machine (SVM) model. Our findings indicate that elevated peripheral ferritin in MDD patients may disrupt the normal metabolism of iron in the brain, leading to abnormal changes in brain iron levels and GMV.