Clinical and Imaging Markers of Prodromal Parkinson's Disease

Early detection of Parkinson's disease: Retinal functional impairments as potential biomarkers

BACKGROUND

Parkinson's disease is typically diagnosed after substantial neurodegeneration despite early non-motor symptoms manifesting decades earlier. These changes offer a promising avenue for diagnostic exploration, especially within the eye, which has been proposed as a "window to the brain."

OBJECTIVE

The aim was to identify biomarkers by validating the use of electroretinography, a non-invasive technique, to detect early retinal function anomalies reflecting central dysfunction.

METHODS

Homozygous M83 transgenic mice (n = 10 males, 11 females), overexpressing human A53T α-synuclein, underwent behavioral tests and electroretinography measurements. Histological evaluation was performed at four months to analyze synucleinopathies and neurodegeneration. Electroretinography was also conducted with idiopathic PD patients (mean age 63.35 ± 7.73; disease duration 4.15 ± 2.06; H&Y score 2.07 ± 0.59; n = 12 males, 8 females) and healthy age-matched controls (mean age 61.65 ± 8.39; n = 9 males, 11 females).

RESULTS

Rodent electroretinography revealed reduced photopic b-wave, PhNR b-wave, and PhNR-wave amplitudes at two and four months, particularly in females, indicating bipolar and retinal ganglion cell impairment. Based on retinal histological assessment, these changes might arise from α-synuclein pathology occurring in outer retinal layers. Likewise, the scotopic b-wave and PhNR waveform were similarly impaired in female participants with Parkinson's disease. The scotopic oscillatory potentials isolated further identified an attenuated amacrine cell output in females.

CONCLUSIONS

Findings from both mice and human cohorts indicate that retinal functional impairments can be detected early in the progression of Parkinson's disease, particularly among females. These tools show promise in facilitating early diagnosis, disease monitoring, therapeutic intervention, and ultimately enhancing patient outcomes.

Multimodal diagnostic tools and advanced data models for detection of prodromal Parkinson's disease: a scoping review

BACKGROUND

Parkinson's Disease (PD) is a progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta. PD is diagnosed by a combination of motor symptoms including bradykinesia, resting tremors, rigidity and postural instability. Prodromal PD is the stage preceding the onset of classic motor symptoms of PD. The diagnosis of prodromal PD remains challenging despite many available diagnostic modalities.

AIM

This scoping review aims to investigate and explore the current diagnostic modalities used to detect prodromal PD, focusing particularly on multimodal imaging analysis and AI-based approaches.

METHODS

We adhered to the PRISMA-SR guidelines for scoping reviews. We conducted a comprehensive literature search at multiple databases such as PubMed, Scopus, Web of Science, and the Cochrane Library from inception to July 2024, using keywords related to prodromal PD and diagnostic modalities. We included studies based on predefined inclusion and exclusion criteria and performed data extraction using a standardized form.

RESULTS

The search included 9 studies involving 567 patients with prodromal PD and 35,643 control. Studies utilized various diagnostic approaches including neuroimaging techniques and AI-driven models. sensitivity ranging from 43 to 84% and specificity up to 96%. Neuroimaging and AI technologies showed promising results in identifying early pathological changes and predicting PD onset. The highest specificity was achieved by neuromelanin-sensitive imaging model, while highest sensitivity was achieved by standard 10-s electrocardiogram (ECG) + Machine learning model.

CONCLUSION

Advanced diagnostic modalities such as AI-driven models and multimodal neuroimaging revealed promising results in early detection of prodromal PD. However, their clinical application as screening tool for prodromal PD is limited because of the lack of validation. Future research should be directed towards using Multimodal imaging in diagnosing and screening for prodromal PD.

CLINICAL TRIAL NUMBER

Not applicable.

Exosomes as Biomarkers and Therapeutic Agents in Neurodegenerative Diseases: Current Insights and Future Directions

Neurodegenerative diseases (NDs) like Alzheimer's, Parkinson's, and ALS rank among the most challenging global health issues, marked by substantial obstacles in early diagnosis and effective treatment. Current diagnostic techniques frequently demonstrate inadequate sensitivity and specificity, whilst conventional treatment strategies encounter challenges related to restricted bioavailability and insufficient blood-brain barrier (BBB) permeability. Recently, exosomes-nanoscale vesicles packed with proteins, RNAs, and lipids-have emerged as promising agents with the potential to reshape diagnostic and therapeutic approaches to these diseases. Unlike conventional drug carriers, they naturally traverse the BBB and can deliver bioactive molecules to affected neural cells. Their molecular cargo can influence cell signaling, reduce neuroinflammation, and potentially slow neurodegenerative progression. Moreover, exosomes serve as non-invasive biomarkers, enabling early and precise diagnosis while allowing real-time disease monitoring. Additionally, engineered exosomes, loaded with therapeutic molecules, enhance this capability by targeting diseased neurons and overcoming conventional treatment barriers. By offering enhanced specificity, reduced immunogenicity, and an ability to bypass physiological limitations, exosome-based strategies present a transformative advantage over existing diagnostic and therapeutic approaches. This review examines the multifaceted role of exosomes in NDDs, emphasizing their diagnostic capabilities, intrinsic therapeutic functions, and transformative potential as advanced treatment vehicles.

Challenges and Opportunities in Exploring Non-Motor Symptoms in 6-Hydroxydopamine Models of Parkinson's Disease: A Systematic Review

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the progressive loss of midbrain dopaminergic neurons, leading to motor symptoms such as tremors, rigidity, and bradykinesia. Non-motor symptoms, including depression, hyposmia, and sleep disturbances, often emerge in the early stages of PD, but their mechanisms remain poorly understood. The 6-hydroxydopamine (6-OHDA) rodent model is a well-established tool for preclinical research, replicating key motor and non-motor symptoms of PD. In this review, we systematically analyzed 135 studies that used 6-OHDA rodent models of PD to investigate non-motor symptoms. The review process adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Our analysis highlights the growing use of 6-OHDA PD models for experimental research of non-motor symptoms. It also reveals significant variability in methodologies, including choices of brain target, toxin dosage, lesion verification strategies, and behavioral assessment reporting. Factors that hinder reproducibility and comparability of findings across studies. We highlight the need for standardization in 6-OHDA-based models with particular emphasis on consistent evaluation of lesion extent and reporting of the co-occurrence of non-motor symptoms. By fostering methodological coherence, this framework aims to enhance the reproducibility, reliability, and translational value of 6-OHDA models in PD non-motor symptom research.

The α-Synuclein Seeding Amplification Assay for Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disease in the world. Currently, PD is incurable, and the diagnosis of PD mainly relies on clinical manifestations. The central pathological event in PD is the abnormal aggregation and deposition of misfolded α-synuclein (α-Syn) protein aggregates in the Lewy body (LB) in affected brain areas. Behaving as a prion-like seeding, the misfolded α-syn protein can induce and facilitate the aggregation of native unfolded α-Syn protein to aggravate α-Syn protein aggregation, leading to PD progression. Recently, in a blood-based α-Syn seeding amplification assay (SAA), Kluge et al. identified pathological α-Syn seeding activity in PD patients with Parkin (PRKN) gene variants. Additionally, pathological α-syn seeding activity was also identified in sporadic PD and PD patients with Leucine-rich repeat kinase 2 (LRRK2) or glucocerebrosidase (GBA) gene variants. Principally, the α-Syn SAA can be used to detect pathological α-Syn seeding activity, which will significantly enhance PD diagnosis, progression monitoring, prognosis prediction, and anti-PD therapy. The significance and future strategies of α-Syn SAA protocol are highlighted and proposed, whereas challenges and limitations of the assay are discussed.

Update on the Role of [18F]FDOPA PET/CT

[18F]-dihydroxyphenylalanine ([18F]FDOPA) is a radiopharmaceutical used in a broad spectrum of diseases, including neuroendocrine tumors (NETs), congenital hyperinsulinism, parkinsonian syndromes and neuro-oncology. Genetic analysis and disease specific biomarkers may guide the optimum selection of patients that may benefit most from [18F]FDOPA PET in different stages of several neuroendocrine neoplasms and in congenital hyperinsulinism. For clinical routine in neuro-oncology, indications for [18F]FDOPA PET include tumor delineation and distinguishing between treatment related changes and recurrent disease. New developments as the advent of large axial field of view PET/CT or integrated PET/MRI systems may provide more unique opportunities, such as those related to detection of smaller lesions in primary staging of NETs, dose reduction in children with congenital hyperinsulinism, or possibilities to obtain more extensive noninvasive quantification of cerebral uptake by using image derived input functions. Although the widespread use of [18F]FDOPA has been hampered by complex synthesis methods and high production costs in the past, significant efforts have been undertaken to provide robust GMP compliant synthesis methods with high activity yield and molar activity.

Ferroptosis-A Shared Mechanism for Parkinson's Disease and Type 2 Diabetes

Type 2 diabetes (T2D) and Parkinson's disease (PD) are the two most frequent age-related chronic diseases. There are many similarities between the two diseases: both are chronic diseases; both are the result of a decrease in a specific substance-insulin in T2D and dopamine in PD; and both are caused by the destruction of specific cells-beta pancreatic cells in T2D and dopaminergic neurons in PD. Recent epidemiological and experimental studies have found that there are common underlying mechanisms in the pathophysiology of T2D and PD: chronic inflammation, mitochondrial dysfunction, impaired protein handling and ferroptosis. Epidemiological research has indicated that there is a higher risk of PD in individuals with T2D. Moreover, clinical studies have observed that the symptoms of Parkinson's disease worsen significantly after the onset of T2D. This article provides an up-to-date review on the intricate interplay between oxidative stress, reactive oxygen species (ROS) and ferroptosis in PD and T2D. By understanding the shared molecular pathways and how they can be modulated, we can develop more effective therapies, or we can repurpose existing drugs to improve patient outcomes in both disorders.

Neurodegenerative disorders: Mechanisms of degeneration and therapeutic approaches with their clinical relevance

Neurodegenerative disorders (NDs) are expected to pose a significant challenge for both medicine and public health in the upcoming years due to global demographic changes. NDs are mainly represented by degeneration/loss of neurons, which is primarily accountable for severe mental illness. This neuronal degeneration leads to many neuropsychiatric problems and permanent disability in an individual. Moreover, the tight junction of the brain, blood-brain barrier (BBB)has a protective feature, functioning as a biological barrier that can prevent medicines, toxins, and foreign substances from entering the brain. However, delivering any medicinal agent to the brain in NDs (i.e., Multiple sclerosis, Alzheimer's, Parkinson's, etc.) is enormously challenging. There are many approved therapies to address NDs, but most of them only help treat the associated manifestations. The available therapies have failed to control the progression of NDs due to certain factors, i.e., BBB and drug-associated undesirable effects. NDs have extremely complex pathology, with many pathogenic mechanisms involved in the initiation and progression; thereby, a limited survival rate has been observed in ND patients. Hence, understanding the exact mechanism behind NDs is crucial to developing alternative approaches for improving ND patients' survival rates. Thus, the present review sheds light on different cellular mechanisms involved in NDs and novel therapeutic approaches with their clinical relevance, which will assist researchers in developing alternate strategies to address the limitations of conventional ND therapies. The current work offers the scope into the near future to improve the therapeutic approach of NDs.

Dopamine in the prefrontal cortex plays multiple roles in the executive function of patients with Parkinson's disease

Parkinson's disease can affect not only motor functions but also cognitive abilities, leading to cognitive impairment. One common issue in Parkinson's disease with cognitive dysfunction is the difficulty in executive functioning. Executive functions help us plan, organize, and control our actions based on our goals. The brain area responsible for executive functions is called the prefrontal cortex. It acts as the command center for the brain, especially when it comes to regulating executive functions. The role of the prefrontal cortex in cognitive processes is influenced by a chemical messenger called dopamine. However, little is known about how dopamine affects the cognitive functions of patients with Parkinson's disease. In this article, the authors review the latest research on this topic. They start by looking at how the dopaminergic system, is altered in Parkinson's disease with executive dysfunction. Then, they explore how these changes in dopamine impact the synaptic structure, electrical activity, and connection components of the prefrontal cortex. The authors also summarize the relationship between Parkinson's disease and dopamine-related cognitive issues. This information may offer valuable insights and directions for further research and improvement in the clinical treatment of cognitive impairment in Parkinson's disease.

A binding-triggered hybridization chain reaction cascade multi-site activated CRISPR/Cas12a signal amplification strategy for sensitive detection of α-synuclein

Alpha-synuclein (α-syn) is closely related to the pathological process of Parkinson's disease (PD). Sensitive detection of α-syn is important for the early diagnosis and disease progression monitoring of PD. Herein, we report a binding-triggered hybridization chain reaction (HCR) cascade multi-site activated CRISPR/Cas12a signal amplification strategy for sensitive detection of α-syn. In this method, antibody-DNA capture probes recognized α-syn and bound with it to increase the local effective concentrations of two DNA strands, promoting their hybridization to form a split HCR trigger. Then the trigger initiated an HCR to generate a long double-stranded structure which contained abundant periodically repeated Cas12a/crRNA target sequences. Finally, the Cas12a/crRNA recognized the target sequence in HCR products and then the cleavage activity toward fluorescent reporters was activated, leading to the recovery of appreciable fluorescence signals. Our method provided a detection limit as low as 9.33 pM and exhibited satisfactory applicability in human serum samples. In summary, this study provides a homogeneous strategy for convenient, sensitive, and accurate detection of α-syn, showing great potential in the early diagnosis of PD.

Risk of Parkinson's disease in people aged ≥50 years with new-onset anxiety: a retrospective cohort study in UK primary care

BACKGROUND

A history of anxiety is more common in people with Parkinson's disease (PD). The prospective risk of PD in those newly presenting with anxiety and factors that increase the risk of PD in patients with anxiety have not been investigated.

AIM

To investigate the incidence of PD in people with anxiety aged ≥50 years and clinical features associated with later diagnosis of PD in people with anxiety.

DESIGN AND SETTING

A retrospective cohort study using UK primary care data between 2008 and 2018, assessing patients with new-onset anxiety aged ≥50 years.

METHOD

Weibull survival regression models were fitted and hazard ratios (HRs) for modelling time-to-PD was estimated in those with and without anxiety, and when determining the risk of developing PD in those with anxiety. Results were adjusted for sociodemographic and lifestyle factors, and relevant physical and mental health conditions.

RESULTS

The risk of PD increased two-fold compared with the non-anxiety group after adjustment for age, sex, social deprivation, lifestyle factors, severe mental illness, head trauma, and dementia (HR 2.1, 95% confidence interval = 1.9 to 2.4). In those with anxiety, the presence of depression, hypotension, tremor, rigidity, balance impairment, constipation, sleep disturbance, fatigue, and cognitive impairment were associated with an increased risk of developing PD.

CONCLUSION

The risk of developing PD was at least doubled in people with anxiety compared with those without. The clinical features of those who developed PD can help identify patients presenting with anxiety who are in the prodromal phase of PD.

Assessment of brain-derived extracellular vesicle enrichment for blood biomarker analysis in age-related neurodegenerative diseases: An international overview

INTRODUCTION

Brain-derived extracellular vesicles (BEVs) in blood allows for minimally-invasive investigations of central nervous system (CNS) -specific markers of age-related neurodegenerative diseases (NDDs). Polymer-based EV- and immunoprecipitation (IP)-based BEV-enrichment protocols from blood have gained popularity. We systematically investigated protocol consistency across studies, and determined CNS-specificity of proteins associated with these protocols.

METHODS

NDD articles investigating BEVs in blood using polymer-based and/or IP-based BEV enrichment protocols were systematically identified, and protocols compared. Proteins used for BEV-enrichment and/or post-enrichment were assessed for CNS- and brain-cell-type-specificity, extracellular domains (ECD+), and presence in EV-databases.

RESULTS

A total of 82.1% of studies used polymer-based (ExoQuick) EV-enrichment, and 92.3% used L1CAM for IP-based BEV-enrichment. Centrifugation times differed across studies. A total of 26.8% of 82 proteins systematically identified were CNS-specific: 50% ECD+, 77.3% were listed in EV-databases.

CONCLUSIONS

We identified protocol steps requiring standardization, and recommend additional CNS-specific proteins that can be used for BEV-enrichment or as BEV-biomarkers.

HIGHLIGHTS

Across NDDs, we identified protocols commonly used for EV/BEV enrichment from blood. We identified protocol steps showing variability that require harmonization. We assessed CNS-specificity of proteins used for BEV-enrichment or found in BEV cargo. CNS-specific EV proteins with ECD+ or without were identified. We recommend evaluation of blood-BEV enrichment using these additional ECD+ proteins.

Imaging Procedure and Clinical Studies of [18F]FP-CIT PET

N-3-[18F]fluoropropyl-2β-carbomethoxy-3β-4-iodophenyl nortropane ([18F]FP-CIT) is a radiopharmaceutical for dopamine transporter (DAT) imaging using positron emission tomography (PET) to detect dopaminergic neuronal degeneration in patients with parkinsonian syndrome. [18F]FP-CIT was granted approval by the Ministry of Food and Drug Safety in 2008 as the inaugural radiopharmaceutical for PET imaging, and it has found extensive utilization across numerous institutions in Korea. This review article presents an imaging procedure for [18F]FP-CIT PET to aid nuclear medicine physicians in clinical practice and systematically reviews the clinical studies associated with [18F]FP-CIT PET.

Peripheral cutaneous synucleinopathy characteristics in genetic Parkinson's disease

Background

Cutaneous phosphorylated alpha-synuclein (p-α-syn) deposition is an important biomarker of idiopathic Parkinson's disease (iPD). Recent studies have reported synucleinopathies in patients with common genetic forms of PD.

Objective

This study aimed to detect p-α-syn deposition characteristic in rare genetic PD patients with CHCHD2 or RAB39B mutations. Moreover, this study also aimed to describe peripheral alpha-synuclein prion-like activity in genetic PD patients, and acquire whether the cutaneous synucleinopathy characteristics of genetic PD are consistent with central neuropathologies.

Methods

We performed four skin biopsy samples from the distal leg (DL) and proximal neck (C7) of 161 participants, including four patients with CHCHD2 mutations, two patients with RAB39B mutations, 16 patients with PRKN mutations, 14 patients with LRRK2 mutations, five patients with GBA mutations, 100 iPD patients, and 20 healthy controls. We detected cutaneous synucleinopathies using immunofluorescence staining and a seeding amplification assay (SAA). A systematic literature review was also conducted, involving 64 skin biopsies and 205 autopsies of genetic PD patients with synucleinopathy.

Results

P-α-syn was deposited in the peripheral cutaneous nerves of PD patients with CHCHD2, LRRK2, or GBA mutations but not in those with RAB39B or PRKN mutations. There were no significant differences in the location or rate of α-syn-positive deposits between genetic PD and iPD patients. Peripheral cutaneous synucleinopathy appears to well represent brain synucleinopathy of genetic PD, especially autosomal dominant PD (AD-PD). Cutaneous α-synuclein SAA analysis of iPD and LRRK2 and GBA mutation patients revealed prion-like activity.

Conclusion

P-α-syn deposition in peripheral cutaneous nerves, detected using SAA and immunofluorescence staining, may serve as an accurate biomarker for genetic PD and iPD in the future.

Towards a biological diagnosis of PD

Since the original description by James Parkinson, Parkinson's disease (PD) has intrigued us for over 200 years. PD is a progressive condition that is incurable so far, and affects millions of people worldwide. Over the years, our knowledge has expanded tremendously, and a range of criteria have been put forward and used to try to define PD. However, owing to the complexity of the problem, it is still not consensual how to diagnose and classify a disease that manifests with diverse features, and that responds differently to existing therapies and to those under development. We are now living a time when 'biological' information is becoming abundant, precise, and accessible enabling us to attempt to incorporate different sources of information to classify different forms of PD. These refinements are essential for basic science, as they will enable us to develop improved models for studying PD, and to implement new findings into clinical practice, as this will be the path towards effective personalized medicine.

Lysosomal storage, impaired autophagy and innate immunity in Gaucher and Parkinson's diseases: insights for drug discovery

Impairment of autophagic-lysosomal pathways is increasingly being implicated in Parkinson's disease (PD). GBA1 mutations cause the lysosomal storage disorder Gaucher disease (GD) and are the commonest known genetic risk factor for PD. GBA1 mutations have been shown to cause autophagic-lysosomal impairment. Defective autophagic degradation of unwanted cellular constituents is associated with several pathologies, including loss of normal protein homeostasis, particularly of α-synuclein, and innate immune dysfunction. The latter is observed both peripherally and centrally in PD and GD. Here, we will discuss the mechanistic links between autophagy and immune dysregulation, and the possible role of these pathologies in communication between the gut and brain in these disorders. Recent work in a fly model of neuronopathic GD (nGD) revealed intestinal autophagic defects leading to gastrointestinal dysfunction and immune activation. Rapamycin treatment partially reversed the autophagic block and reduced immune activity, in association with increased survival and improved locomotor performance. Alterations in the gut microbiome are a critical driver of neuroinflammation, and studies have revealed that eradication of the microbiome in nGD fly and mouse models of PD ameliorate brain inflammation. Following these observations, lysosomal-autophagic pathways, innate immune signalling and microbiome dysbiosis are discussed as potential therapeutic targets in PD and GD. This article is part of a discussion meeting issue 'Understanding the endo-lysosomal network in neurodegeneration'.

Intranasal Administration of GRP78 Protein (HSPA5) Confers Neuroprotection in a Lactacystin-Induced Rat Model of Parkinson's Disease

The accumulation of misfolded and aggregated α-synuclein can trigger endoplasmic reticulum (ER) stress and the unfolded protein response (UPR), leading to apoptotic cell death in patients with Parkinson's disease (PD). As the major ER chaperone, glucose-regulated protein 78 (GRP78/BiP/HSPA5) plays a key role in UPR regulation. GRP78 overexpression can modulate the UPR, block apoptosis, and promote the survival of nigral dopamine neurons in a rat model of α-synuclein pathology. Here, we explore the therapeutic potential of intranasal exogenous GRP78 for preventing or slowing PD-like neurodegeneration in a lactacystin-induced rat model. We show that intranasally-administered GRP78 rapidly enters the substantia nigra pars compacta (SNpc) and other afflicted brain regions. It is then internalized by neurons and microglia, preventing the development of the neurodegenerative process in the nigrostriatal system. Lactacystin-induced disturbances, such as the abnormal accumulation of phosphorylated pS129-α-synuclein and activation of the pro-apoptotic GRP78/PERK/eIF2α/CHOP/caspase-3,9 signaling pathway of the UPR, are substantially reversed upon GRP78 administration. Moreover, exogenous GRP78 inhibits both microglia activation and the production of proinflammatory cytokines, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), via the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway in model animals. The neuroprotective and anti-inflammatory potential of exogenous GRP78 may inform the development of effective therapeutic agents for PD and other synucleinopathies.

Nicotinic Acetylcholine Receptors in Glial Cells as Molecular Target for Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by resting tremor, bradykinesia, rigidity, and postural instability that also includes non-motor symptoms such as mood dysregulation. Dopamine (DA) is the primary neurotransmitter involved in this disease, but cholinergic imbalance has also been implicated. Current intervention in PD is focused on replenishing central DA, which provides remarkable temporary symptomatic relief but does not address neuronal loss and the progression of the disease. It has been well established that neuronal nicotinic cholinergic receptors (nAChRs) can regulate DA release and that nicotine itself may have neuroprotective effects. Recent studies identified nAChRs in nonneuronal cell types, including glial cells, where they may regulate inflammatory responses. Given the crucial role of neuroinflammation in dopaminergic degeneration and the involvement of microglia and astrocytes in this response, glial nAChRs may provide a novel therapeutic target in the prevention and/or treatment of PD. In this review, following a brief discussion of PD, we focus on the role of glial cells and, specifically, their nAChRs in PD pathology and/or treatment.

Ferroptosis regulation through Nrf2 and implications for neurodegenerative diseases

This article provides an overview of the background knowledge of ferroptosis in the nervous system, as well as the key role of nuclear factor E2-related factor 2 (Nrf2) in regulating ferroptosis. The article takes Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS) as the starting point to explore the close association between Nrf2 and ferroptosis, which is of clear and significant importance for understanding the mechanism of neurodegenerative diseases (NDs) based on oxidative stress (OS). Accumulating evidence links ferroptosis to the pathogenesis of NDs. As the disease progresses, damage to the antioxidant system, excessive OS, and altered Nrf2 expression levels, especially the inhibition of ferroptosis by lipid peroxidation inhibitors and adaptive enhancement of Nrf2 signaling, demonstrate the potential clinical significance of Nrf2 in detecting and identifying ferroptosis, as well as targeted therapy for neuronal loss and mitochondrial dysfunction. These findings provide new insights and possibilities for the treatment and prevention of NDs.

Harmonizing multisite data with the ComBat method for enhanced Parkinson's disease diagnosis via DAT-SPECT

Background

Dopamine transporter single-photon emission computed tomography (DAT-SPECT) is a crucial tool for evaluating patients with Parkinson's disease (PD). However, its implication is limited by inter-site variability in large multisite clinical trials. To overcome the limitation, a conventional prospective correction method employs linear regression with phantom scanning, which is effective yet available only in a prospective manner. An alternative, although relatively underexplored, involves retrospective modeling using a statistical method known as "combatting batch effects when combining batches of gene expression microarray data" (ComBat).

Methods

We analyzed DAT-SPECT-specific binding ratios (SBRs) derived from 72 healthy older adults and 81 patients with PD registered in four clinical sites. We applied both the prospective correction and the retrospective ComBat correction to the original SBRs. Next, we compared the performance of the original and two corrected SBRs to differentiate the PD patients from the healthy controls. Diagnostic accuracy was assessed using the area under the receiver operating characteristic curve (AUC-ROC).

Results

The original SBRs were 6.13 ± 1.54 (mean ± standard deviation) and 2.03 ± 1.41 in the control and PD groups, respectively. After the prospective correction, the mean SBRs were 6.52 ± 1.06 and 2.40 ± 0.99 in the control and PD groups, respectively. After the retrospective ComBat correction, the SBRs were 5.25 ± 0.89 and 2.01 ± 0.73 in the control and PD groups, respectively, resulting in substantial changes in mean values with fewer variances. The original SBRs demonstrated fair performance in differentiating PD from controls (Hedges's g = 2.76; AUC-ROC = 0.936). Both correction methods improved discrimination performance. The ComBat-corrected SBR demonstrated comparable performance (g = 3.99 and AUC-ROC = 0.987) to the prospectively corrected SBR (g = 4.32 and AUC-ROC = 0.992) for discrimination.

Conclusion

Although we confirmed that SBRs fairly discriminated PD from healthy older adults without any correction, the correction methods improved their discrimination performance in a multisite setting. Our results support the utility of harmonization methods with ComBat for consolidating SBR-based diagnosis or stratification of PD in multisite studies. Nonetheless, given the substantial changes in the mean values of ComBat-corrected SBRs, caution is advised when interpreting them.

Program with last minute abstracts of the Padua Days on Muscle and Mobility Medicine, 27 February - 2 March, 2024 (2024Pdm3)

During the 2023 Padua Days on Muscle and Mobility Medicine the 2024 meeting was scheduled from 28 February to 2 March 2024 (2024Pdm3). During autumn 2023 the program was expanded with Scientific Sessions which will take place over five days (in 2024 this includes February 29), starting from the afternoon of 27 February 2024 in the Conference Rooms of the Hotel Petrarca, Thermae of Euganean Hills (Padua), Italy. As per consolidated tradition, the second day will take place in Padua, for the occasion in the Sala San Luca of the Monastery of Santa Giustina in Prato della Valle, Padua, Italy. Confirming the attractiveness of the Padua Days on Muscle and Mobility Medicine, over 100 titles were accepted until 15 December 2023 (many more than expected), forcing the organization of parallel sessions on both 1 and 2 March 2024. The five days will include lectures and oral presentations of scientists and clinicians from Argentina, Austria, Belgium, Brazil, Bulgaria, Canada, Denmark, Egypt, France, Germany, Iceland, Ireland, Italy, Romania, Russia, Slovenia, Switzerland, UK and USA. Only Australia, China, India and Japan are missing from this edition. But we are confident that authors from those countries who publish articles in the PAGEpress: European Journal of Translational Myology (EJTM: 2022 ESCI Clarivate's Impact Factor: 2.2; SCOPUS Cite Score: 3.2) will decide to join us in the coming years. Together with the program established by 31 January 2024, the abstracts will circulate during the meeting only in the electronic version of the EJTM Issue 34 (1) 2024. See you soon in person at the Hotel Petrarca in Montegrotto Terme, Padua, for the inauguration scheduled the afternoon of 27 February 2024 or on-line for free via Zoom. Send us your email address if you are not traditional participants listed in Pdm3 and EJTM address books.

Intensive training programme improves handwriting in a community cohort of people with Parkinson's disease

BACKGROUND

People with Parkinson's disease (PwP) often report problems with their handwriting before they receive a formal diagnosis. Many PwP suffer from deteriorating handwriting throughout their illness, which has detrimental effects on many aspects of their quality of life.

AIMS

To assess a 6-week online training programme aimed at improving handwriting of PwP.

METHODS

Handwriting samples from a community-based cohort of PwP (n = 48) were analysed using systematic detection of writing problems (SOS-PD) by two independent raters, before and after a 6-week remotely monitored physiotherapy-led training programme. Inter-rater variability on multiple measures of handwriting quality was analysed. The handwriting data was analysed using pre-/post-design in the same individuals. Multiple aspects of the handwriting samples were assessed, including writing fluency, transitions between letters, regularity in letter size, word spacing, and straightness of lines.

RESULTS

Analysis of inter-rater reliability showed high agreement for total handwriting scores and letter size, as well as speed and legibility scores, whereas there were mixed levels of inter-rater reliability for other handwriting measures. Overall handwriting quality (p = 0.001) and legibility (p = 0.009) significantly improved, while letter size (p = 0.012), fluency (p = 0.001), regularity of letter size (p = 0.009), and straightness of lines (p = 0.036) were also enhanced.

CONCLUSIONS

The results of this study show that this 6-week intensive remotely-monitored physiotherapy-led handwriting programme improved handwriting in PwP. This is the first study of its kind to use this tool remotely, and it demonstrated that the SOS-PD is reliable for measuring handwriting in PwP.

Retinal Alterations Predict Early Prodromal Signs of Neurodegenerative Disease

Neurodegenerative diseases are an increasingly common group of diseases that occur late in life with a significant impact on personal, family, and economic life. Among these, Alzheimer's disease (AD) and Parkinson's disease (PD) are the major disorders that lead to mild to severe cognitive and physical impairment and dementia. Interestingly, those diseases may show onset of prodromal symptoms early after middle age. Commonly, the evaluation of these neurodegenerative diseases is based on the detection of biomarkers, where functional and structural magnetic resonance imaging (MRI) have shown a central role in revealing early or prodromal phases, although it can be expensive, time-consuming, and not always available. The aforementioned diseases have a common impact on the visual system due to the pathophysiological mechanisms shared between the eye and the brain. In Parkinson's disease, α-synuclein deposition in the retinal cells, as well as in dopaminergic neurons of the substantia nigra, alters the visual cortex and retinal function, resulting in modifications to the visual field. Similarly, the visual cortex is modified by the neurofibrillary tangles and neuritic amyloid β plaques typically seen in the Alzheimer's disease brain, and this may reflect the accumulation of these biomarkers in the retina during the early stages of the disease, as seen in postmortem retinas of AD patients. In this light, the ophthalmic evaluation of retinal neurodegeneration could become a cost-effective method for the early diagnosis of those diseases, overcoming the limitations of functional and structural imaging of the deep brain. This analysis is commonly used in ophthalmic practice, and interest in it has risen in recent years. This review will discuss the relationship between Alzheimer's disease and Parkinson's disease with retinal degeneration, highlighting how retinal analysis may represent a noninvasive and straightforward method for the early diagnosis of these neurodegenerative diseases.

Aquaporin-4 and Parkinson's Disease

The water-selective channel aquaporin-4 (AQP4) is implicated in water homeostasis and the functioning of the glymphatic system, which eliminates various metabolites from the brain tissue, including amyloidogenic proteins. Misfolding of the α-synuclein protein and its post-translational modifications play a crucial role in the development of Parkinson's disease (PD) and other synucleopathies, leading to the formation of cytotoxic oligomers and aggregates that cause neurodegeneration. Human and animal studies have shown an interconnection between AQP4 dysfunction and α-synuclein accumulation; however, the specific role of AQP4 in these mechanisms remains unclear. This review summarizes the current knowledge on the role of AQP4 dysfunction in the progression of α-synuclein pathology, considering the possible effects of AQP4 dysregulation on brain molecular mechanisms that can impact α-synuclein modification, accumulation and aggregation. It also highlights future directions that can help study the role of AQP4 in the functioning of the protective mechanisms of the brain during the development of PD and other neurodegenerative diseases.

Combining Biomarkers with Genetics In Prodromal/Earliest Phase Parkinson's Disease

 Family studies have linked several rare genetic variants to hereditary forms of Parkinson's disease (PD). In addition to these monogenic forms, many PD cases are associated with genetic risk factors. Asymptomatic individuals carrying pathogenic variants linked to PD are at risk of developing the disease later in life, thereby providing a unique opportunity for the detection of the earliest pathophysiological and later clinical changes and, importantly, also of protective and compensatory features and mechanisms. However, the rarity of monogenic PD-causing variants is a major challenge of this approach. In this review, we discuss recent advances in the search for biomarkers in the prodromal/earliest phase of genetically linked PD.

Alpha-Synuclein Contribution to Neuronal and Glial Damage in Parkinson's Disease

Parkinson's disease (PD) is a complex neurodegenerative disease characterized by the progressive loss of dopaminergic neurons in the substantia nigra and the widespread accumulation of alpha-synuclein (αSyn) protein aggregates. αSyn aggregation disrupts critical cellular processes, including synaptic function, mitochondrial integrity, and proteostasis, which culminate in neuronal cell death. Importantly, αSyn pathology extends beyond neurons-it also encompasses spreading throughout the neuronal environment and internalization by microglia and astrocytes. Once internalized, glia can act as neuroprotective scavengers, which limit the spread of αSyn. However, they can also become reactive, thereby contributing to neuroinflammation and the progression of PD. Recent advances in αSyn research have enabled the molecular diagnosis of PD and accelerated the development of targeted therapies. Nevertheless, despite more than two decades of research, the cellular function, aggregation mechanisms, and induction of cellular damage by αSyn remain incompletely understood. Unraveling the interplay between αSyn, neurons, and glia may provide insights into disease initiation and progression, which may bring us closer to exploring new effective therapeutic strategies. Herein, we provide an overview of recent studies emphasizing the multifaceted nature of αSyn and its impact on both neuron and glial cell damage.

Exploring the interplay between metabolomics and genetics in Parkinson's disease: Insights from ongoing research and future avenues

Parkinson's disease (PD) is a widespread neurodegenerative disorder, whose complex aetiology remains under construction. While rare variants have been associated with the monogenic PD form, most PD cases are influenced by multiple genetic and environmental aspects. Nonetheless, the pathophysiological pathways and molecular networks involved in monogenic/idiopathic PD overlap, and genetic variants are decisive in elucidating the convergent underlying mechanisms of PD. In this scenario, metabolomics has furnished a dynamic and systematic picture of the synergy between the genetic background and environmental influences that impact PD, making it a valuable tool for investigating PD-related metabolic dysfunctions. In this review, we performed a brief overview of metabolomics current research in PD, focusing on significant metabolic alterations observed in idiopathic PD from different biofluids and strata and exploring how they relate to genetic factors associated with monogenic PD. Dysregulated amino acid metabolism, lipid metabolism, and oxidative stress are the critical metabolic pathways implicated in both genetic and idiopathic PD. By merging metabolomics and genetics data, it is possible to distinguish metabolic signatures of specific genetic backgrounds and to pinpoint subgroups of PD patients who could derive personalized therapeutic benefits. This approach holds great promise for advancing PD research and developing innovative, cost-effective treatments.

Gut-microbiome-brain axis: the crosstalk between the vagus nerve, alpha-synuclein and the brain in Parkinson's disease

This critical review of the literature shows that there is a close link between the microbiome, the gut, and the brain in Parkinson's disease. The vagus nerve, the main component of the parasympathetic nervous system, is involved in the regulation of immune response, digestion, heart rate, and control of mood. It can detect microbiota metabolites through its afferents, transferring this gut information to the central nervous system. Preclinical and clinical studies have shown the important role played by the gut microbiome and gut-related factors in disease development and progression, as well as treatment responses. These findings suggest that the gut microbiome may be a valuable target for new therapeutic strategies for Parkinson's disease. More studies are needed to better understand the underlying biology and how this axis can be modulated for the patient's benefit.

Treatment of Parkinson's disease with biologics that penetrate the blood-brain barrier via receptor-mediated transport

Parkinson's disease (PD) is characterized by neurodegeneration of nigral-striatal neurons in parallel with the formation of intra-neuronal α-synuclein aggregates, and these processes are exacerbated by neuro-inflammation. All 3 components of PD pathology are potentially treatable with biologics. Neurotrophins, such as glial derived neurotrophic factor or erythropoietin, can promote neural repair. Therapeutic antibodies can lead to disaggregation of α-synuclein neuronal inclusions. Decoy receptors can block the activity of pro-inflammatory cytokines in brain. However, these biologic drugs do not cross the blood-brain barrier (BBB). Biologics can be made transportable through the BBB following the re-engineering of the biologic as an IgG fusion protein, where the IgG domain targets an endogenous receptor-mediated transcytosis (RMT) system within the BBB, such as the insulin receptor or transferrin receptor. The receptor-specific antibody domain of the fusion protein acts as a molecular Trojan horse to ferry the biologic into brain via the BBB RMT pathway. This review describes the re-engineering of all 3 classes of biologics (neurotrophins, decoy receptor, therapeutic antibodies) for BBB delivery and treatment of PD. Targeting the RMT pathway at the BBB also enables non-viral gene therapy of PD using lipid nanoparticles (LNP) encapsulated with plasmid DNA encoding therapeutic genes. The surface of the lipid nanoparticle is conjugated with a receptor-specific IgG that triggers RMT of the LNP across the BBB in vivo.

Assessment of brain-derived extracellular vesicle enrichment for blood biomarker analysis in age-related neurodegenerative diseases: An international overview

INTRODUCTION

Brain-derived extracellular vesicles (BEVs) in blood allows for minimally- invasive investigations of CNS-specific markers of age-related neurodegenerative diseases (NDDs). Polymer-based EV- and immunoprecipitation (IP)-based BEV-enrichment protocols from blood have gained popularity. We systematically investigated protocol consistency across studies, and determined CNS-specificity of proteins associated with these protocols.

METHODS

NDD articles investigating BEVs in blood using polymer-based and/or IP-based BEV enrichment protocols were systematically identified, and protocols compared. Proteins used for BEV-enrichment and/or post-enrichment were assessed for CNS- and brain-cell-type- specificity; extracellular domains (ECD+); and presence in EV-databases.

RESULTS

82.1% of studies used polymer-based (ExoQuick) EV-enrichment, and 92.3% used L1CAM for IP-based BEV-enrichment. Centrifugation times differed across studies. 26.8% of 82 proteins systematically identified were CNS-specific: 50% ECD+, 77.3% were listed in EV- databases.

DISCUSSION

We identified protocol steps requiring standardization, and recommend additional CNS-specific proteins that can be used for BEV-enrichment or as BEV-biomarkers.

Assessing traffic-related air pollution-induced fiber-specific white matter degradation associated with motor performance declines in aged rats

Fine particulate matter (PM2.5) is thought to exacerbate Parkinson's disease (PD) in the elderly, and early detection of PD progression may prevent further irreversible damage. Therefore, we used diffusion tensor imaging (DTI) for probing microstructural changes after late-life chronic traffic-related PM2.5 exposure. Herein, 1.5-year-old Fischer 344 rats were exposed to clean air (control), high-efficiency particulate air (HEPA)-filtered ambient air (HEPA group), and ambient traffic-related PM2.5 (PM2.5 group, 9.933 ± 1.021 µg/m3) for 3 months. Rotarod test, DTI tractographic analysis, and immunohistochemistry were performed in the end of study period. Aged rats exposed to PM2.5 exhibited motor impairment with decreased fractional anisotropy and tyrosine hydroxylase expression in olfactory and nigrostriatal circuits, indicating disrupted white matter integrity and dopaminergic (DA) neuronal loss. Additionally, increased radial diffusivity and lower expression of myelin basic protein in PM2.5 group suggested ageing progression of demyelination exacerbated by PM2.5 exposure. Significant production of tumor necrosis factor-α was also observed after PM2.5 exposure, revealing potential inflammation of injury to multiple fiber tracts of DA pathways. Microstructural changes demonstrated potential links between PM2.5-induced inflammatory white matter demyelination and behavioral performance, with indication of pre-manifestation of DTI-based biomarkers for early detection of PD progression in the elderly.

Modeling Parkinson's disease in LRRK2 rodents

Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are associated with familial and sporadic forms of Parkinson's disease (PD). Sporadic PD and LRRK2 PD share main clinical and neuropathological features, namely hypokinesia, degeneration of nigro-striatal dopamine neurons and α-synuclein aggregates in the form of Lewy bodies. Animals harboring the most common LRRK2 mutations, i.e. p.G2019S and p.R1441C/G, have been generated to replicate the parkinsonian phenotype and investigate the underlying pathogenic mechanisms. Disappointingly, however, LRRK2 rodents did not consistently phenocopy hypokinesia and nigro-striatal degeneration, or showed Lewy body-like aggregates. Instead, LRRK2 rodents manifested non-motor signs and dysregulated transmission at dopaminergic and non-dopaminergic synapses that are reminiscent of behavioral and functional network changes observed in the prodromal phase of the disease. LRRK2 rodents also manifested greater susceptibility to different parkinsonian toxins or stressors when subjected to dual-hit or multiple-hit protocols, confirming LRRK2 mutations as genetic risk factors. In conclusion, LRRK2 rodents represent a unique tool to identify the molecular mechanisms through which LRRK2 modulates the course and clinical presentations of PD and to study the interplay between genetic, intrinsic and environmental protective/risk factors in PD pathogenesis.

A review on chitosan and alginate-based microcapsules: Mechanism and applications in drug delivery systems

Natural polymers, like chitosan and alginate have potential of appearance, as well as the changes and handling necessary to make it acceptable vehicle for the controlled release of medicines and biomolecules. Microcapsules are characterized as micrometer-sized particulate that can be employed to store chemicals within them. In the present review, we have discussed various advantages, components of microcapsules, release mechanisms, preparation methods, and their applications in drug delivery systems. The preparation methods exhibited strong encapsulation effectiveness and may be used in a wide range of pharmaceutical and biomedical applications. The major advantages of using the microencapsulation technique are, sustained and controlled delivery of drugs, drug targeting, improvement of shelf life, stabilization, immobilization of enzymes and microorganisms. As new biomaterials are developed for the body, they are better suited to the development of pharmaceutical systems than traditional pharmaceuticals because they are more reliable, biocompatible, biodegradable, and nontoxic. Furthermore, the designed microcapsules had been capable of shielding the essential components from hostile environments. More advanced techniques could be developed in the future to facilitate the formulation and applications of microcapsules and working with the pharmaceutical and medical industries.

Wearable movement-tracking data identify Parkinson's disease years before clinical diagnosis

Parkinson's disease is a progressive neurodegenerative movement disorder with a long latent phase and currently no disease-modifying treatments. Reliable predictive biomarkers that could transform efforts to develop neuroprotective treatments remain to be identified. Using UK Biobank, we investigated the predictive value of accelerometry in identifying prodromal Parkinson's disease in the general population and compared this digital biomarker with models based on genetics, lifestyle, blood biochemistry or prodromal symptoms data. Machine learning models trained using accelerometry data achieved better test performance in distinguishing both clinically diagnosed Parkinson's disease (n = 153) (area under precision recall curve (AUPRC) 0.14 ± 0.04) and prodromal Parkinson's disease (n = 113) up to 7 years pre-diagnosis (AUPRC 0.07 ± 0.03) from the general population (n = 33,009) compared with all other modalities tested (genetics: AUPRC = 0.01 ± 0.00, P = 2.2 × 10-3; lifestyle: AUPRC = 0.03 ± 0.04, P = 2.5 × 10-3; blood biochemistry: AUPRC = 0.01 ± 0.00, P = 4.1 × 10-3; prodromal signs: AUPRC = 0.01 ± 0.00, P = 3.6 × 10-3). Accelerometry is a potentially important, low-cost screening tool for determining people at risk of developing Parkinson's disease and identifying participants for clinical trials of neuroprotective treatments.

Machine learning models for diagnosis and prognosis of Parkinson's disease using brain imaging: general overview, main challenges, and future directions

Parkinson's disease (PD) is a progressive and complex neurodegenerative disorder associated with age that affects motor and cognitive functions. As there is currently no cure, early diagnosis and accurate prognosis are essential to increase the effectiveness of treatment and control its symptoms. Medical imaging, specifically magnetic resonance imaging (MRI), has emerged as a valuable tool for developing support systems to assist in diagnosis and prognosis. The current literature aims to improve understanding of the disease's structural and functional manifestations in the brain. By applying artificial intelligence to neuroimaging, such as deep learning (DL) and other machine learning (ML) techniques, previously unknown relationships and patterns can be revealed in this high-dimensional data. However, several issues must be addressed before these solutions can be safely integrated into clinical practice. This review provides a comprehensive overview of recent ML techniques analyzed for the automatic diagnosis and prognosis of PD in brain MRI. The main challenges in applying ML to medical diagnosis and its implications for PD are also addressed, including current limitations for safe translation into hospitals. These challenges are analyzed at three levels: disease-specific, task-specific, and technology-specific. Finally, potential future directions for each challenge and future perspectives are discussed.

Gene Panel Sequencing Analysis Revealed a Strong Contribution of Rare Coding Variants to the Risk of Parkinson's Disease in Sporadic Moroccan Patients

Parkinson's disease (PD) is a neurodegenerative movement disorder which can be either familial or sporadic. While it is well known that monogenic mutations are not a very common cause of PD, GWAS studies have shown that an additional fraction of the PD heritability could be explained by rare or common variants. To identify the rare variants that could influence the risk of PD in the Moroccan population, a cohort of 94 sporadic PD patients negative for the LRRK2 G2019S mutation was subjected to NGS gene panel sequencing, and gene dosage using the MLPA method. Mean age of onset at enrollment was 51.7 ± 11.51 years, and 60% of patients were men. We identified 70 rare variants under 0.5% of frequency in 16 of the 20 genes analyzed, of which 7 were novel. Biallelic disease-causing variants in genes with recessive inheritance were found in 5 PD cases (5.31%), whereas 13 patients (13.8%) carried likely pathogenic variants in genes with dominant inheritance. Moreover, 8 patients (8.5%) carried a single variant in MAPT or POLG, whereas co-occurrence of rare variants involving more than one gene was observed in 28 patients (30%). PD patients with variants in recessive genes had a younger mean age at onset than patients with dominant ones (33.40 (12.77) vs. 53.15 (6.63), p < 0.001), while their clinical features were similar. However, patients with rare variants in the risk factor genes or in more than one gene tended to have less resting tremor (p < 0.04), but more dystonia (p < 0.006) and dementia (p < 0.002) than those without any rare variants in known PD-associated genes. Our results showed a significant enrichment of rare variants particularly in LRRK2, VPS13C, POLG, and MAPT and underline their impact on the risk of sporadic form of the disease.

Monitoring Substantia Nigra Degeneration Using Free Water Imaging across Prodromal and Clinical Parkinson's Disease

BACKGROUND

Substantia nigra (SN) free water has been suggested as a good surrogate marker in Parkinson's disease (PD). However, its usefulness for diagnosing prodromal PD (pPD) and monitoring disease progression warrants further validation.

OBJECTIVE

The aim was to investigate SN free water values across prodromal and clinical stages of PD.

METHODS

Four groups were enrolled in this study: 48 healthy controls (HC), 43 pPD patients, 50 de novo PD (dnPD) patients, and 49 medicated PD (mPD) patients. Based on diffusion tensor images, free water maps were calculated, and SN free water values were extracted from the anterior SN (ASN) and posterior SN (PSN). The SN free water values were compared among the four groups, and associations between free water and clinical symptoms were explored. The distinguishing power of PSN free water was evaluated using the receiver operating characteristic curve analysis. Follow-up was performed for 14 pPD patients.

RESULTS

PSN free water in the pPD group was significantly higher than that in the HC group and significantly lower than that in the dnPD group. Surprisingly, the mPD group showed decreased PSN free water compared to the dnPD group. There was a positive correlation between motor symptoms and PSN free water in the pPD and dnPD groups. Longitudinal analysis showed a significant increase in PSN free water in pPD patients over time.

CONCLUSIONS

The PSN free water increased from prodromal to early clinical stages, but the trend might be reversed in late disease stages. This biphasic trend should be considered when applying this marker in future studies. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Recent Advances in the Treatment of Genetic Forms of Parkinson's Disease: Hype or Hope?

Parkinson's disease (PD) is a multifarious neurodegenerative disease. Its pathology is characterized by a prominent early death of dopaminergic neurons in the pars compacta of the substantia nigra and the presence of Lewy bodies with aggregated α-synuclein. Although the α-synuclein pathological aggregation and propagation, induced by several factors, is considered one of the most relevant hypotheses, PD pathogenesis is still a matter of debate. Indeed, environmental factors and genetic predisposition play an important role in PD. Mutations associated with a high risk for PD, usually called monogenic PD, underlie 5% to 10% of all PD cases. However, this percentage tends to increase over time because of the continuous identification of new genes associated with PD. The identification of genetic variants that can cause or increase the risk of PD has also given researchers the possibility to explore new personalized therapies. In this narrative review, we discuss the recent advances in the treatment of genetic forms of PD, focusing on different pathophysiologic aspects and ongoing clinical trials.

The theoretical problems of "prodrome" and "phenoconversion" in neurodegeneration

The recognition of and approach to prodromal symptoms, those which manifest before a diagnosis can be ascertained at the bedside, are of increasing interest in neurodegenerative research. A prodrome is conceived of as an early window into a disease, a critical time when putative disease-modifying interventions may be best suited for examination. Several challenges affect research in this area. Prodromal symptoms are highly prevalent in the population, can be nonprogressive for years or decades, and exhibit limited specificity in predicting conversion versus nonconversion into a neurodegenerative category within a time window feasible for most longitudinal clinical studies. In addition, there is a large range of biological alterations subsumed within each prodromal syndrome, forced to converge into the unifying nosology of each neurodegenerative disorder. Initial prodromal subtyping efforts have been developed but given the scarcity of prodrome-to-disease longitudinal studies, it is not yet clear whether any prodromal subtype can be predicted to evolve into the corresponding subtype of manifesting disease - a form of construct validity. As current subtypes generated from one clinical population are not faithfully replicated to others, it is likely that, lacking biological or molecular anchors, prodromal subtypes may only be applicable to the cohorts within which they were developed. Furthermore, as clinical subtypes have not aligned with a consistent pattern of pathology or biology, such might also be the fate of prodromal subtypes. Finally, the threshold defining the change from prodrome to disease for most neurodegenerative disorders remains clinical (e.g., a motor change in gait becoming noticeable to a clinician or measurable with portable technologies), not biological. As such, a prodrome can be viewed as a disease state not yet overt to a clinician. Efforts into identifying biological subtypes of disease, regardless of clinical phenotype or disease stage, may best serve future disease-modifying therapeutic strategies deployed not for a prodromal symptom but for a defined biological derangement as soon as it can be determined to lead to clinical changes, prodromal or not.

How should future clinical trials be designed in the search for disease-modifying therapies for Parkinson's disease?

INTRODUCTION

Although there has been substantial progress in research and innovations in symptomatic treatments, similar success has not been achieved in disease-modifying therapy (DMT) for Parkinson's disease (PD). Considering the enormous motor, psychosocial and financial burden associated with PD, safe and effective DMT is of paramount importance.

AREAS COVERED

One of the reasons for the lack of progress in DMT for PD is poor or inappropriate design of clinical trials. In the first part of the article, the authors focus on the plausible reasons why the previous trials have failed and in the latter part, they provide their perspectives on future DMT trials.

EXPERT OPINION

There are several potential reasons why previous trials have failed, including broad clinical and etiopathogenic heterogeneity of PD, poor definition and documentation of target engagement, lack of appropriate biomarkers and outcome measures, and short duration of follow-up. To address these deficiencies, future trials may consider- (i) a more customized approach to select the most suitable participants and therapeutic approaches, (ii) explore combination therapies that would target multiple pathogenetic mechanisms, and (iii) moving beyond targeting only motor symptoms to also assessing non-motor features of PD in well-designed longitudinal studies.

Non-motor symptoms in multiple system atrophy: A comparative study with Parkinson's disease and progressive supranuclear palsy

Background

Non-motor symptoms (NMS) are compulsory clinical features for the clinical diagnosis of multiple system atrophy (MSA), some of which precede motor symptoms onset. To date, few studies have systematically investigated NMS in MSA and the timing of presenting NMS as the disease progresses. Clinically, MSA is difficult to be differentiated from Parkinson's disease (PD) and progressive supranuclear palsy (PSP), and the differences in NMS between MSA and PD/PSP remain unclear. The aim of this study was to compare the burden of NMS between MSA and PD/PSP and to delineate the timing of NMS presentation relative to the onset of motor symptoms in MSA.

Methods

A total of 61, 87, and 30 patients with MSA, PD, and PSP, respectively, were enrolled in this study. NMS was systematically assessed in all patients using the NMS scale (NMSS), and the onset of NMS relative to the onset of motor symptoms in MSA was investigated.

Results

MSA group had higher total NMSS scores (82.15 ± 46.10) than the PD (36.14 ± 30.78) and PSP (50.30 ± 55.05) groups (p < 0.001 overall). The number distribution pattern of the NMS was significantly different among the three parkinsonian disorders (p < 0.001 overall). In total, 85.2% of patients with MSA had more than 10 NMS, which was significantly higher than PD (28.7%) and PSP (33.3%). The frequency and scores of many NMSS subdomains and symptoms were higher in MSA than in PD and PSP (all p < 0.05). Multivariate logistic regression analysis revealed that patients with fainting, lack of motivation, swallowing, and loss of sexual interest could be attributed to MSA rather than PD or PSP, while patients with loss of concentration and forgetfulness were characteristic features of PD or PSP rather than MSA. REM-sleep behavior disorder (RBD), constipation, problems having sex, and loss of sexual interest preceded the motor symptoms onset of MSA by 2.81 ± 4.51, 1.54 ± 6.32, 1.35 ± 4.70, and 0.45 ± 3.61 years, respectively.

Conclusion

The NMS spectrum in MSA differs from that of PD and PSP. Patients with MSA have a higher NMS burden than patients with PD or PSP. RBD, constipation, problems having sex, and loss of sexual interest may become early diagnostic clinical markers of MSA.

The Role of Fecal Microbiota Transplantation in the Treatment of Neurodegenerative Diseases: A Review

Neurodegenerative diseases are highly prevalent but poorly understood, and with few treatment options despite decades of intense research, attention has recently shifted toward other mediators of neurological disease that may present future targets for therapeutic research. One such mediator is the gut microbiome, which communicates with the brain through the gut-brain axis and has been implicated in various neurological disorders. Alterations in the gut microbiome have been associated with numerous neurological and other diseases, and restoration of the dysbiotic gut has been shown to improve disease conditions. One method of restoring a dysbiotic gut is via fecal microbiota transplantation (FMT), recolonizing the "diseased" gut with normal microbiome. Fecal microbiota transplantation is a treatment method traditionally used for Clostridium difficile infections, but it has recently been used in neurodegenerative disease research as a potential treatment method. This review aims to present a summary of neurodegenerative research that has used FMT, whether as a treatment or to investigate how the microbiome influences pathogenesis.

Parkinson's disease classification with CWNN: Using wavelet transformations and IMU data fusion for improved accuracy

BACKGROUND

Parkinson's disease (PD) is a chronic neurodegenerative disorder characterized by motor impairments and various other symptoms. Early and accurate classification of PD patients is crucial for timely intervention and personalized treatment. Inertial measurement units (IMUs) have emerged as a promising tool for gathering movement data and aiding in PD classification.

OBJECTIVE

This paper proposes a Convolutional Wavelet Neural Network (CWNN) approach for PD classification using IMU data. CWNNs have emerged as effective models for sensor data classification. The objective is to determine the optimal combination of wavelet transform and IMU data type that yields the highest classification accuracy for PD.

METHODS

The proposed CWNN architecture integrates convolutional neural networks and wavelet neural networks to capture spatial and temporal dependencies in IMU data. Different wavelet functions, such as Morlet, Mexican Hat, and Gaussian, are employed in the continuous wavelet transform (CWT) step. The CWNN is trained and evaluated using various combinations of accelerometer data, gyroscope data, and fusion data.

RESULTS

Extensive experiments are conducted using a comprehensive dataset of IMU data collected from individuals with and without PD. The performance of the proposed CWNN is evaluated in terms of classification accuracy, precision, recall, and F1-score. The results demonstrate the impact of different wavelet functions and IMU data types on PD classification performance, revealing that the combination of Morlet wavelet function and IMU data fusion achieves the highest accuracy.

CONCLUSION

The findings highlight the significance of combining CWT with IMU data fusion for PD classification using CWNNs. The integration of CWT-based feature extraction and the fusion of IMU data from multiple sensors enhance the representation of PD-related patterns, leading to improved classification accuracy. This research provides valuable insights into the potential of CWT and IMU data fusion for advancing PD classification models, enabling more accurate and reliable diagnosis.

Chronobiology of Parkinson's disease: Past, present and future

Parkinson's disease is a neurodegenerative disorder predominately affecting midbrain dopaminergic neurons that results in a broad range of motor and non-motor symptoms. Sleep complaints are among the most common non-motor symptoms, even in the prodromal period. Sleep alterations in Parkinson's disease patients may be associated with dysregulation of circadian rhythms, intrinsic 24-h cycles that control essential physiological functions, or with side effects from levodopa medication and physical and mental health challenges. The impact of circadian dysregulation on sleep disturbances in Parkinson's disease is not fully understood; as such, we review the systems, cellular and molecular mechanisms that may underlie circadian perturbations in Parkinson's disease. We also discuss the potential benefits of chronobiology-based personalized medicine in the management of Parkinson's disease both in terms of behavioural and pharmacological interventions. We propose that a fuller understanding of circadian clock function may shed important new light on the aetiology and symptomatology of the disease and may allow for improvements in the quality of life for the millions of people with Parkinson's disease.

Fenofibrate promotes neuroprotection in a model of rotenone-induced Parkinson's disease

Parkinson's disease is a neurodegenerative disease, the etiology of which remains unknown, but some likely causes include oxidative stress, mitochondrial dysfunction and neuroinflammation. Peroxisome-proliferator-activated receptor (PPAR) agonists have been studied in animal models of Parkinson's disease and have shown neuroprotective effects. In this study, we aimed to (1) confirm the neuroprotective effects of PPAR-alpha agonist fenofibrate. To this end, male rats received fenofibrate (100 mg/kg) orally for 15 days, 5 days before the intraperitoneal injections of rotenone (2.5 mg/kg for 10 days). After finishing the treatment with rotenone and fenofibrate, animals were subjected to the open field, the forced swim test and the two-way active avoidance task. Subsequently, rats were euthanized for measurement of dopamine and metabolites levels in the striatum and quantification of tyrosine hydroxylase-immunoreactive neurons in the substantia nigra pars compacta (SNpc). In addition, we aimed to (2) evaluate the neuroprotective effects of fenofibrate on the accumulation of α-synuclein aggregates. Here, rats were treated for 5 days with fenofibrate continuing for over 28 days with rotenone. Then, animals were perfused for immunohistochemistry analysis of α-synuclein. The results showed that fenofibrate reduced depressive-like behavior and memory impairment induced by rotenone. Moreover, fenofibrate diminished the depletion of striatal dopamine and protected against dopaminergic neuronal death in the SNpc. Likewise, the administration of fenofibrate attenuated the aggregation of α-synuclein in the SNpc and striatum in the rotenone-lesioned rats. Our study confirmed that fenofibrate exerted neuroprotective effects because parkinsonian rats exhibited reduced behavioral, neurochemical and immunohistochemical changes, and importantly, a lower number of α-synuclein aggregates.

Association between Parkinson's Disease Medication and the Risk of Lower Urinary Tract Infection (LUTI): A Retrospective Cohort Study

BACKGROUND

The occurrence of autonomic dysfunctions (e.g., urological dysfunctions) is a common phenomenon during the course of Parkinson's disease (PD) and resulting complications such as lower urinary tract infections (LUTI) are one of the leading causes of hospitalizations and mortality in patients with the condition. Therefore, the aim of this retrospective cohort study was to compare the most common levodopa-based treatment regimens (DOPA decarboxylase inhibitor (DCI) + carbidopa or benserazide) and to analyze the incidence of LUTI and antibiotic prescriptions in patients receiving the respective treatments.

METHODS

This study was based on data from the Disease Analyzer database (IQVIA) and included adult patients (≥18 years) with an initial prescription of levodopa therapy including fixed-dose levodopa/DCI combinations in 1284 general practices in Germany between January 2010 and December 2020. Conditional Cox regression models were used to analyze the association between levodopa/DCI combinations and LUTI incidence and antibiotic prescriptions.

RESULTS

Compared to levodopa + carbidopa, levodopa + benserazide therapy was significantly and negatively associated with LUTI (HR: 0.82; 95% CI: 0.71-0.95). This association was stronger in women (HR: 0.77; 95% CI: 0.65-0.92) than in men (HR: 0.93, not significant).

CONCLUSIONS

Especially in women, receiving levodopa + benserazide prescriptions was associated with a lower LUTI incidence. It is important for clinicians to keep this in mind, since LUTI is a leading cause of hospitalizations, morbidity, and mortality in patients with PD.

Neuromelanin and T2*-MRI for the assessment of genetically at-risk, prodromal, and symptomatic Parkinson's disease

MRI was suggested as a promising method for the diagnosis and assessment of Parkinson's Disease (PD). We aimed to assess the sensitivity of neuromelanin-MRI and T₂* with radiomics analysis for detecting PD, identifying individuals at risk, and evaluating genotype-related differences. Patients with PD and non-manifesting (NM) participants [NM-carriers (NMC) and NM-non-carriers (NMNC)], underwent MRI and DAT-SPECT. Imaging-based metrics included 48 neuromelanin and T₂* radiomics features and DAT-SPECT specific-binding-ratios (SBR), were extracted from several brain regions. Imaging values were assessed for their correlations with age, differences between groups, and correlations with the MDS-likelihood-ratio (LR) score. Several machine learning classifiers were evaluated for group classification. A total of 127 participants were included: 46 patients with PD (62.3 ± 10.0 years) [15:LRRK2-PD, 16:GBA-PD, and 15:idiopathic-PD (iPD)], 47 NMC (51.5 ± 8.3 years) [24:LRRK2-NMC and 23:GBA-NMC], and 34 NMNC (53.5 ± 10.6 years). No significant correlations were detected between imaging parameters and age. Thirteen MRI-based parameters and radiomics features demonstrated significant differences between PD and NMNC groups. Support-Vector-Machine (SVM) classifier achieved the highest performance (AUC = 0.77). Significant correlations were detected between LR scores and two radiomic features. The classifier successfully identified two out of three NMC who converted to PD. Genotype-related differences were detected based on radiomic features. SBR values showed high sensitivity in all analyses. In conclusion, neuromelanin and T₂* MRI demonstrated differences between groups and can be used for the assessment of individuals at-risk in cases when DAT-SPECT can't be performed. Combining neuromelanin and T₂*-MRI provides insights into the pathophysiology underlying PD, and suggests that iron accumulation precedes neuromelanin depletion during the prodromal phase.

Brain age vector: A measure of brain aging with enhanced neurodegenerative disorder specificity

Neuroimaging‐driven brain age estimation has become popular in measuring brain aging and identifying neurodegenerations. However, the single estimated brain age (gap) compromises regional variations of brain aging, losing spatial specificity across diseases which is valuable for early screening. In this study, we combined brain age modeling with Shapley Additive Explanations to measure brain aging as a feature contribution vector underlying spatial pathological aging mechanism. Specifically, we regressed age with volumetric brain features using machine learning to construct the brain age model, and model‐agnostic Shapley values were calculated to attribute regional brain aging for each subject's age estimation, forming the brain age vector. Spatial specificity of the brain age vector was evaluated among groups of normal aging, prodromal Parkinson disease (PD), stable mild cognitive impairment (sMCI), and progressive mild cognitive impairment (pMCI). Machine learning methods were adopted to examine the discriminability of the brain age vector in early disease screening, compared with the other two brain aging metrics (single brain age gap, regional brain age gaps) and brain volumes. Results showed that the proposed brain age vector accurately reflected disorder‐specific abnormal aging patterns related to the medial temporal and the striatum for prodromal AD (sMCI vs. pMCI) and PD (healthy controls [HC] vs. prodromal PD), respectively, and demonstrated outstanding performance in early disease screening, with area under the curves of 83.39% and 72.28% in detecting pMCI and prodromal PD, respectively. In conclusion, the proposed brain age vector effectively improves spatial specificity of brain aging measurement and enables individual screening of neurodegenerative diseases.