Parkinson's: a syndrome rather than a disease?

Advances in autonomic dysfunction research in Parkinson's disease

Parkinson's disease (PD) is a prevalent neurodegenerative disorder, best known for its motor symptoms such as resting tremor, muscle rigidity, and bradykinesia. However, autonomic dysfunction is an important non-motor aspect that often brings considerable discomfort and distress to both patients and their families. In this review, we summarize recent advances in understanding the pathophysiological mechanisms of autonomic dysfunction and explore its relationship with other clinical features. Our aim is to discover novel potential diagnostic and therapeutic strategies, alleviate patient suffering, and pave the way for future clinical and basic research.

Association between serum IGF‑1 levels and non-motor symptoms in Parkinson's disease

AIMS

We aimed to measure serum insulin-like growth factor 1 (IGF-1) levels in Parkinson's disease (PD) patients and assess their correlation with non-motor symptoms (NMS).

BACKGROUND

Emerging evidence suggests that abnormal levels of IGF-1 play a crucial role in the development of PD.

OBJECTIVE

Further systematic research is needed to explore the potential roles of abnormal IGF-1 levels in NMS of PD.

METHODS

The study enrolled a total of 129 PD patients and 130 healthy controls (HCs). Within the PD cohort, 74 patients were classified as being in the early stage, while 55 were in the moderate stage.

RESULTS

This study found no significant difference in serum IGF-1 levels between PD patients and HC. Further analysis revealed no significant difference in IGF-1 levels between early-stage PD and those in the moderate stages. Linear regression analysis indicated a significant association between serum IGF-1 levels and Nonmotor Symptom Scale (NMSS) scores in PD patients. Linear regression analysis revealed significant correlations between serum IGF-1 levels and general cognitive function, information processing speed, and executive function in PD patients. Furthermore, lower serum IGF-1 levels were associated with fatigue in PD patients.

CONCLUSIONS

In summary, our study suggests a potential association between serum IGF-1 levels and specific NMS in patients with PD. These findings highlight the importance of long-term follow-up studies to determine whether serum biomarkers can serve as valuable tools for early detection of NMS in PD.

Porphyromonas gingivalis: a potential trigger of neurodegenerative disease

Porphyromonas gingivalis (P. gingivalis) is a gram-negative bacterium and the main causative agent of periodontitis, a disease closely associated with the development of periodontal disease. The progression of periodontitis, a chronic infectious disease, is intricately linked to the inflammatory immune response. Inflammatory cytokines act on periodontal tissues via immunomodulation, resulting in the destruction of the periodontal tissue. Recent studies have established connections between periodontitis and various systemic diseases, including cardiovascular diseases, tumors, and neurodegenerative diseases. Neurodegenerative diseases are neurological disorders caused by immune system dysfunction, including Alzheimer's and Parkinson's diseases. One of the main characteristics of neurodegenerative diseases is an impaired inflammatory response, which mediates neuroinflammation through microglial activation. Some studies have shown an association between periodontitis and neurodegenerative diseases, with P. gingivalis as the primary culprit. P. gingivalis can cross the blood-brain barrier (BBB) or mediate neuroinflammation and injury through a variety of pathways, including the gut-brain axis, thereby affecting neuronal growth and survival and participating in the onset and progression of neurodegenerative diseases. However, comprehensive and systematic summaries of studies on the infectious origin of neurodegenerative diseases are lacking. This article reviews and summarizes the relationship between P. gingivalis and neurodegenerative diseases and its possible regulatory mechanisms. This review offers new perspectives into the understanding of neurodegenerative disease development and highlights innovative approaches for investigating and developing tailored medications for treating neurodegenerative conditions, particularly from the viewpoint of their association with P. gingivalis.

The immune system in Parkinson's disease: what we know so far

Parkinson's disease is characterized neuropathologically by the degeneration of dopaminergic neurons in the ventral midbrain, the accumulation of α-synuclein (α-syn) aggregates in neurons and chronic neuroinflammation. In the past two decades, in vitro, ex vivo and in vivo studies have consistently shown the involvement of inflammatory responses mediated by microglia and astrocytes, which may be elicited by pathological α-syn or signals from affected neurons and other cell types, and are directly linked to neurodegeneration and disease development. Apart from the prominent immune alterations seen in the CNS, including the infiltration of T cells into the brain, more recent studies have demonstrated important changes in the peripheral immune profile within both the innate and adaptive compartments, particularly involving monocytes, CD4+ and CD8+ T cells. This review aims to integrate the consolidated understanding of immune-related processes underlying the pathogenesis of Parkinson's disease, focusing on both central and peripheral immune cells, neuron-glia crosstalk as well as the central-peripheral immune interaction during the development of Parkinson's disease. Our analysis seeks to provide a comprehensive view of the emerging knowledge of the mechanisms of immunity in Parkinson's disease and the implications of this for better understanding the overall pathogenesis of this disease.

Beyond the usual suspects: multi-factorial computational models in the search for neurodegenerative disease mechanisms

From Alzheimer's disease to amyotrophic lateral sclerosis, the molecular cascades underlying neurodegenerative disorders remain poorly understood. The clinical view of neurodegeneration is confounded by symptomatic heterogeneity and mixed pathology in almost every patient. While the underlying physiological alterations originate, proliferate, and propagate potentially decades before symptomatic onset, the complexity and inaccessibility of the living brain limit direct observation over a patient's lifespan. Consequently, there is a critical need for robust computational methods to support the search for causal mechanisms of neurodegeneration by distinguishing pathogenic processes from consequential alterations, and inter-individual variability from intra-individual progression. Recently, promising advances have been made by data-driven spatiotemporal modeling of the brain, based on in vivo neuroimaging and biospecimen markers. These methods include disease progression models comparing the temporal evolution of various biomarkers, causal models linking interacting biological processes, network propagation models reproducing the spatial spreading of pathology, and biophysical models spanning cellular- to network-scale phenomena. In this review, we discuss various computational approaches for integrating cross-sectional, longitudinal, and multi-modal data, primarily from large observational neuroimaging studies, to understand (i) the temporal ordering of physiological alterations, i(i) their spatial relationships to the brain's molecular and cellular architecture, (iii) mechanistic interactions between biological processes, and (iv) the macroscopic effects of microscopic factors. We consider the extents to which computational models can evaluate mechanistic hypotheses, explore applications such as improving treatment selection, and discuss how model-informed insights can lay the groundwork for a pathobiological redefinition of neurodegenerative disorders.

Hearing dysfunction heralds an increase in non-motor burden and a worse quality of life in Parkinson's disease: new insights from non-motor spectrum

BACKGROUND

Sensorial non-motor symptoms (NMSs) in Parkinson's disease (PD) still lack appropriate investigation in clinical practice. This study aimed to assess if and to what extent auditory dysfunction is associated with other NMSs in PD and its impact on patient's quality of life (QoL).

METHODS

We selected patients with idiopathic PD, without other concomitant neurological diseases, dementia, or diagnosis of any audiological/vestibular disease. Demographic and clinical data were collected. Patients underwent otoscopic examination, audiological testing with pure tone audiometry (PTA) and distortion product otoacoustic emissions (DPOAEs) and completed Non-Motor Symptoms Scale (NMSS) and Parkinson's Disease Questionnaires-39 (PDQ-39). ANCOVA and partial correlation analysis have been used for statistical analysis.

RESULTS

60 patients were enrolled and completed PTA and DPOAEs. 32 patients with hearing impairment (HI), assessed by PTA, (hearing threshold ≥ 25 dB) showed similar disease duration, motor impairment, and staging, compared to patients without HI, but higher scores both in NMSS and in PDQ-39, except for cardiovascular (CV), gastrointestinal (GI), urogenital (U) and sexual function (SF) of NMSS. In addition, DPOAEs showed a significant correlation with higher scores both in NMSS and PDQ-39, except for CV, SF, GI, U and perceptual problem subdomains of NMSS.

CONCLUSION

This study demonstrated that PD patients with HI have a greater burden of NMS and lower related QoL and functioning. Our results highlight the importance to reconsider HI as a NMS, in parallel with the others. HI evaluation, even in asymptomatic patients, may reveal a wider pathology with a worse QoL.

Association between NEK1 gene polymorphisms and the potential risk of sporadic Parkinson's disease in the Chinese Northern Han population: A case-control study

OBJECTIVE

Parkinson's disease (PD) has been identified as a genetically influenced disease linked to various genetic loci. Previous studies have suggested that neurodegenerative illnesses, including PD, Alzheimer's disease, and Amyotrophic lateral sclerosis (ALS), may share certain genetic loci. Recently, the NEK1 gene was identified as overlapping between PD and ALS. We therefore wanted to explore the potential association between the NEK1 gene single nucleotide polymorphisms (SNPs) and the clinical features and pathophysiology of sporadic PD in a northern Chinese population.

METHODS

A total of 510 sporadic PD patients and 510 age- and sex-matched healthy controls (HCs) were included in this study. Two SNPs (rs4563461 and rs66509122) of the NEK1 gene were genotyped using polymerase chain reaction (PCR). And we analyzed the association between NEK1 gene polymorphisms and clinical manifestations.

RESULTS

Allele T (C vs. T, P = 0.018) and genotype TT (CC vs. TT: P = 0.021) of rs66509122 among PD group and HCs were significantly different. In addition, we discovered that the rs66509122 genotype TT was associated with depression in early-onset PD (EOPD) (P = 0.031) and diabetes in female PD (P = 0.032). Unfortunately, no distinct correlation of rs4563461 polymorphisms with sporadic PD susceptibility was found in either the overall group (C vs. T, P = 0.086) or other subgroups. However, the T allele of rs4563461 was significantly correlated with sleep disorders in the PD group, especially in the late-onset PD (LOPD) group and male PD group.

CONCLUSION

This study found that the NEK1 rs66509122 polymorphism was associated with a lower risk of sporadic PD, while T allele of rs66509122 may be a protective factor for PD. The NEK1 rs4563461 and rs66509122 polymorphisms both showed correlations with some non-motor symptoms in sporadic PD patients. Further research with a larger sample and varied ethnic groups is needed to investigate the role of NEK1 gene polymorphisms in the pathophysiology of PD.

Experimental Parkinson models and green chemistry approach

Parkinson's is the most common neurodegenerative disease after Alzheimer's. Motor findings in Parkinson's occur as a result of the degeneration of dopaminergic neurons starting in the substantia nigra pars compacta and ending in the putamen and caudate nucleus. Loss of neurons and the formation of inclusions called Lewy bodies in existing neurons are characteristic histopathological findings of Parkinson's. The disease primarily impairs the functional capacity of the person with cardinal findings such as tremor, bradykinesia, etc., as a result of the loss of dopaminergic neurons in the substantia nigra. Experimental animal models of Parkinson's have been used extensively in recent years to investigate the pathology of this disease. These models are generally based on systemic or local(intracerebral) administration of neurotoxins, which can replicate many features of Parkinson's mammals. The development of transgenic models in recent years has allowed us to learn more about the modeling of Parkinson's. Applying animal modeling, which shows the most human-like effects in studies, is extremely important. It has been demonstrated that oxidative stress increases in many neurodegenerative diseases such as Parkinson's and various age-related degenerative diseases in humans and that neurons are sensitive to it. In cases where oxidative stress increases and antioxidant systems are inadequate, natural molecules such as flavonoids and polyphenols can be used as a new antioxidant treatment to reduce neuronal reactive oxygen species and improve the neurodegenerative process. Therefore, in this article, we examined experimental animal modeling in Parkinson's disease and the effect of green chemistry approaches on Parkinson's disease.

Blood-brain barrier alterations and their impact on Parkinson's disease pathogenesis and therapy

There is increasing evidence for blood-brain barrier (BBB) alterations in Parkinson's disease (PD), the second most common neurodegenerative disorder with rapidly rising prevalence. Altered tight junction and transporter protein levels, accumulation of α-synuclein and increase in inflammatory processes lead to extravasation of blood molecules and vessel degeneration. This could result in a self-perpetuating pathophysiology of inflammation and BBB alteration, which contribute to neurodegeneration. Toxin exposure or α-synuclein over-expression in animal models has been shown to initiate similar pathologies, providing a platform to study underlying mechanisms and therapeutic interventions. Here we provide a comprehensive review of the current knowledge on BBB alterations in PD patients and how rodent models that replicate some of these changes can be used to study disease mechanisms. Specific challenges in assessing the BBB in patients and in healthy controls are discussed. Finally, a potential role of BBB alterations in disease pathogenesis and possible implications for therapy are explored. The interference of BBB alterations with current and novel therapeutic strategies requires more attention. Brain region-specific BBB alterations could also open up novel opportunities to target specifically vulnerable neuronal subpopulations.

Speech's syllabic rhythm and articulatory features produced under different auditory feedback conditions identify Parkinsonism

Diagnostic tests for Parkinsonism based on speech samples have shown promising results. Although abnormal auditory feedback integration during speech production and impaired rhythmic organization of speech are known in Parkinsonism, these aspects have not been incorporated into diagnostic tests. This study aimed to identify Parkinsonism using a novel speech behavioral test that involved rhythmically repeating syllables under different auditory feedback conditions. The study included 30 individuals with Parkinson's disease (PD) and 30 healthy subjects. Participants were asked to rhythmically repeat the PA-TA-KA syllable sequence, both whispering and speaking aloud under various listening conditions. The results showed that individuals with PD had difficulties in whispering and articulating under altered auditory feedback conditions, exhibited delayed speech onset, and demonstrated inconsistent rhythmic structure across trials compared to controls. These parameters were then fed into a supervised machine-learning algorithm to differentiate between the two groups. The algorithm achieved an accuracy of 85.4%, a sensitivity of 86.5%, and a specificity of 84.3%. This pilot study highlights the potential of the proposed behavioral paradigm as an objective and accessible (both in cost and time) test for identifying individuals with Parkinson's disease.

Emerging perspectives on precision therapy for Parkinson's disease: multidimensional evidence leading to a new breakthrough in personalized medicine

PD is a prevalent and progressive neurodegenerative disorder characterized by both motor and non-motor symptoms. Genes play a significant role in the onset and progression of the disease. While the complexity and pleiotropy of gene expression networks have posed challenges for gene-targeted therapies, numerous pathways of gene variant expression show promise as therapeutic targets in preclinical studies, with some already in clinical trials. With the recognition of the numerous genes and complex pathways that can influence PD, it may be possible to take a novel approach to choose a treatment for the condition. This approach would be based on the symptoms, genomics, and underlying mechanisms of the disease. We discuss the utilization of emerging genetic and pathological knowledge of PD patients to categorize the disease into subgroups. Our long-term objective is to generate new insights for the therapeutic approach to the disease, aiming to delay and treat it more effectively, and ultimately reduce the burden on individuals and society.

Soluble LRP-1 in Parkinson's disease: clues for paradoxical effects

Background: Low density lipoprotein receptor-related protein-1 (LRP-1) is highly expressed in the central nervous system and plays a role in neurodegenerative disorders. The available data on this subject-matter seem to support the presence of a correlation between LRP-1 levels and abnormal aggregation of a plurality of proteins, including tau, amyloid, and α‑synuclein. Understanding the molecular mechanisms underlying Parkinson's disease (PD) is critical for development of new therapies.

Aim: To investigate serum soluble LRP-1 (sLRP-1) concentrations in patients with PD and explored their potential role as a biomarker in diagnosis and prognosis of disease.

Methods: Based on well-defined inclusion and exclusion criteria, we have included 133 PD patients and 45 healthy controls. The clinical severity was assessed using Hoehn Yahr and Unified PD Rating Scale (UPDRS). Following a fasting period, venous blood samples were taken, and centrifuged. Serum samples were stored until analysis. sLRP-1 was measured by ELISA assay.

Results: The median of serum sLRP-1 levels was higher in PD patients compared to that in healthy controls, but without reaching a statistical significance. There was a positive, but statistically insignificant, correlation between sLRP-1 levels and duration of disease. sLRP-1 levels had a significant correlation with UPDRS Parts I and IV. Patients with hypertension showed lower levels of sLRP-1.

Conclusion: The present study suggests that serum sLRP-1 concentrations are associated with the factors influencing prognosis of PD and disease severity. Further studies are needed to definitively determine whether or not sLRP-1 can be utilized as a diagnostic and prognostic biomarker for PD.

Novel gene signatures predicting and immune infiltration analysis in Parkinson's disease: based on combining random forest with artificial neural network

BACKGROUND

Parkinson's disease (PD) ranks as the second most prevalent neurodegenerative disorder globally, and its incidence is rapidly rising. The diagnosis of PD relies on clinical characteristics. Although current treatments aim to alleviate symptoms, they do not effectively halt the disease's progression. Early detection and intervention hold immense importance. This study aimed to establish a new PD diagnostic model.

METHODS

Data from a public database were adopted for the construction and validation of a PD diagnostic model with random forest and artificial neural network models. The CIBERSORT platform was applied for the evaluation of immune cell infiltration in PD. Quantitative real-time PCR was performed to verify the accuracy and reliability of the bioinformatics analysis results.

RESULTS

Leveraging existing gene expression data from the Gene Expression Omnibus (GEO) database, we sifted through differentially expressed genes (DEGs) in PD and identified 30 crucial genes through a random forest classifier. Furthermore, we successfully designed a novel PD diagnostic model using an artificial neural network and verified its diagnostic efficacy using publicly available datasets. Our research also suggests that mast cells may play a significant role in the onset and progression of PD.

CONCLUSION

This work developed a new PD diagnostic model with machine learning techniques and suggested the immune cells as a potential target for PD therapy.

Refining the clinical diagnosis of Parkinson's disease

Our ability to define, understand, and classify Parkinson's disease (PD) has undergone significant changes since the disorder was first described in 1817. Clinical features and neuropathologic signatures can now be supplemented by in-vivo interrogation of genetic and biological substrates of disease, offering great opportunity for further refining the diagnosis of PD. In this mini-review, we discuss the historical perspectives which shaped our thinking surrounding the definition and diagnosis of PD. We highlight the clinical, genetic, pathologic and biologic diversity which underpins the condition, and proceed to discuss how recent developments in our ability to define biologic and pathologic substrates of disease might impact PD definition, diagnosis, individualised prognostication, and personalised clinical care. We argue that Parkinson's 'disease', as currently diagnosed in the clinic, is actually a syndrome. It is the outward manifestation of any array of potential dysfunctional biologic processes, neuropathological changes, and disease aetiologies, which culminate in common outward clinical features which we term PD; each person has their own unique disease, which we can now define with increasing precision. This is an exciting time in PD research and clinical care. Our ability to refine the clinical diagnosis of PD, incorporating in-vivo assessments of disease biology, neuropathology, and neurogenetics may well herald the era of biologically-based, precision medicine approaches PD management. With this however comes a number of challenges, including how to integrate these technologies into clinical practice in a way which is acceptable to patients, promotes meaningful changes to care, and minimises health economic impact.

Depression is associated with the nonmotor symptoms of Parkinson's disease: A comparative analysis

Background and aims

The nonmotor symptoms (NMS) of Parkinson's disease (PD) and their potential role in early diagnosis are recent debates. Herein, we aimed to investigate the association between depression and NMS of PD including sleep disorders, hyposexuality, hyposmia, constipation, and orthostatic hypotension.

Methods

A total of 93 PD patients with depression and 67 PD patients without depression were included in the study, and NMS were compared between the two groups. Furthermore, the possible associations between depression severity measured by Beck Depression Inventory (BDI) and NMS were investigated using linear regression or binary logistic regression models controlled for possible confounders. Eventually, we performed a subgroup analysis in each mild, moderate, and severe depression group.

Results

Orthostatic hypotension, constipation, and hyposexuality showed a significant difference between PD patients with and without depression (p < 0.001, p = 0.029, and p < 0.001, respectively). The BDI score was significantly associated with hyposexuality, Montreal cognitive assessment (MoCA), and Pittsburgh Sleep Quality (p = 0.016, p = 0.010, and p = 0.011, respectively); however, after adjustments for possible confounders, the associations of the BDI score with the MoCA score and hyposexuality remained significant (p = 0.015 and p = 0.019, respectively). Considering subgroup analysis, a similar pattern of significant results was observed particularly in the severe group.

Conclusions

This study suggests a possible association between depression in PD patients and some NMS observed in the course of PD. These findings could be beneficial for early diagnosis of the disease, which eventually could make a considerable difference in the management of PD patients. Additional interventional longitudinal studies are warranted to explore how controlling depression could impact the NMS of patients with PD.

Investigating underlying brain structures and influence of mild and subjective cognitive impairment on dual-task performance in people with Parkinson's disease

Cognitive impairment can affect dual-task abilities in Parkinson's disease (PD), but it remains unclear whether this is also driven by gray matter alterations across different cognitive classifications. Therefore, we investigated associations between dual-task performance during gait and functional mobility and gray matter alterations and explored whether these associations differed according to the degree of cognitive impairment. Participants with PD were classified according to their cognitive function with 22 as mild cognitive impairment (PD-MCI), 14 as subjective cognitive impairment (PD-SCI), and 20 as normal cognition (PD-NC). Multiple regression models associated dual-task absolute and interference values of gait speed, step-time variability, and reaction time, as well as dual-task absolute and difference values for Timed Up and Go (TUG) with PD cognitive classification. We repeated these regressions including the nucleus basalis of Meynert, dorsolateral prefrontal cortex, and hippocampus. We additionally explored whole-brain regressions with dual-task measures to identify dual-task-related regions. There was a trend that cerebellar alterations were associated with worse TUG dual-task in PD-SCI, but also with higher dual-task gait speed and higher dual-task step-time variability in PD-NC. After multiple comparison corrections, no effects of interest were significant. In summary, no clear set of variables associated with dual-task performance was found that distinguished between PD cognitive classifications in our cohort. Promising but non-significant trends, in particular regarding the TUG dual-task, do however warrant further investigation in future large-scale studies.

Peripheral extracellular vesicles in neurodegeneration: pathogenic influencers and therapeutic vehicles

Neurodegenerative diseases (NDDs) such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis epitomize a class of insidious and relentless neurological conditions that are difficult to cure. Conventional therapeutic regimens often fail due to the late onset of symptoms, which occurs well after irreversible neurodegeneration has begun. The integrity of the blood-brain barrier (BBB) further impedes efficacious drug delivery to the central nervous system, presenting a formidable challenge in the pharmacological treatment of NDDs. Recent scientific inquiries have shifted focus toward the peripheral biological systems, investigating their influence on central neuropathology through the lens of extracellular vesicles (EVs). These vesicles, distinguished by their ability to breach the BBB, are emerging as dual operatives in the context of NDDs, both as conveyors of pathogenic entities and as prospective vectors for therapeutic agents. This review critically summarizes the burgeoning evidence on the role of extracerebral EVs, particularly those originating from bone, adipose tissue, and gut microbiota, in modulating brain pathophysiology. It underscores the duplicity potential of peripheral EVs as modulators of disease progression and suggests their potential as novel vehicles for targeted therapeutic delivery, positing a transformative impact on the future landscape of NDD treatment strategies. Search strategy A comprehensive literature search was conducted using PubMed, Web of Science, and Scopus from January 2000 to December 2023. The search combined the following terms using Boolean operators: "neurodegenerative disease" OR "Alzheimer's disease" OR "Parkinson's disease" OR "Amyotrophic lateral sclerosis" AND "extracellular vesicles" OR "exosomes" OR "outer membrane vesicles" AND "drug delivery systems" AND "blood-brain barrier". MeSH terms were employed when searching PubMed to refine the results. Studies were included if they were published in English, involved human subjects, and focused on the peripheral origins of EVs, specifically from bone, adipose tissue, and gut microbiota, and their association with related diseases such as osteoporosis, metabolic syndrome, and gut dysbiosis. Articles were excluded if they did not address the role of EVs in the context of NDDs or did not discuss therapeutic applications. The titles and abstracts of retrieved articles were screened using a dual-review process to ensure relevance and accuracy. The reference lists of selected articles were also examined to identify additional relevant studies.

High-frequency multimodal training with a focus on Tai Chi in people with Parkinson's disease: a pilot study

Background and objectives

Cognitive decline is an important and common complication in patients with Parkinson's disease (PD) since it significantly reduces the quality of life. A breakthrough in treating and preventing cognitive decline in PD remains to be achieved. This study aimed to evaluate the effectiveness of high-frequency and intensive multimodal training in improving motor and cognitive function.

Methods

Twenty-eight patients diagnosed with idiopathic PD completed a comprehensive neuropsychological test battery and were neurologically examined. The patients of the intervention group (n = 15) underwent 2 weekly sessions of Tai Chi therapy over 4 weeks and participated in an individually tailored training program consisting of two modules (smartphone-based speech training and cognitive training). A matched control group consisted of n = 13 patients with PD who received computer-assisted cognitive training. The data were analyzed with repeated-measures ANOVA.

Results

Four weeks of high-frequency training showed significant effects on verbal and figural episodic memory and visuospatial function in the intervention group. Compared to the control group, the cognitive performance of the intervention group improved significantly in visuospatial function and figural episodic memory. A significant improvement was also shown in the intervention group in the Tinetti Mobility Test and the Epworth Sleepiness Scale. The significant effects in the Tinetti mobility test remained after the 6 months follow-up. After the intervention, the patients reported high motivation and satisfaction with the multimodal training.

Conclusion

In patients with PD, a multimodal training program not only improves gait and stability but may also contribute to improving cognition.

Clinical trial registration

ClinicalTrials.gov Identifier: NCT04103255; https://register.clinicaltrials.gov/prs/app/action/LoginUser?ts=1&cx=-jg9qo4.

Constipation and pain in Parkinson's disease: a clinical analysis

Parkinson's Disease (PD) is a neurodegenerative disorder characterized by both motor and non-motor symptoms (NMS). Among NMS, constipation and pain are both highly prevalent and debilitating affecting up to 80% of PD patients and impairing their quality of life. Here, we investigated the relationship between constipation and pain in PD patients. This is a retrospective study assessing the relationship between pain and constipation in a PD patient population from a clinical database of patients attending the outpatient clinic of the movement disorders division, Neurology Unit of Policlinico Tor Vergata, in Rome. Subjects were assessed with the Unified Parkinson's Disease Rating Scale (UPDRS) part III, Hoehn and Yahr (H&Y) stage, King's Parkinson's Disease Pain Scale (KPPS), Brief Pain Inventory (BPI), Non-Motor Symptoms Scale (NMSS) and Beck Depression Inventory (BDI). Patients were further divided in two groups (Group 1, 32 patients with constipation and Group 2, 35 PD patients without constipation) ANOVA and ANCOVA analysis were used to compare the two groups. PD patients with constipation had significantly higher pain severity and pain interference, as measured by the BPI scale and higher total KPPS score, fluctuation-related pain, nocturnal pain, and radicular pain when compared to PD patients without constipation. This study highlights for the first time a possible interplay between constipation and pain in PD that deserves further investigations.

Exercise-Induced Functional Changes in People with Parkinson's Disease following External Cueing and Task-Based Intervention

Introduction

The purpose of this study was to evaluate change in motor function, gait speed, dynamic balance, balance confidence, and quality of life (QoL) in nine participants with Parkinson's disease (PwPD) completing Lee Silverman Voice Treatment BIG (LSVT-BIG), an external cueing and task-based intervention. Although supported as an efficacious treatment in PwPD, there is limited research examining clinically meaningful change in outcome measures related to external cueing and task-based interventions.

Materials and Methods

This was a case series of nine PwPD (age range 64-76 years, 55% male) who completed the LSVT-BIG protocol. Disease duration ranged from 1 to 17 years and was classified as moderate in all participants (Hoehn and Yahr = 2 or 3). Outcome measures included motor function (MDS-UPDRS Part III Motor), gait speed, dynamic balance (MiniBEST), Activities-specific Balance Confidence (ABC), and Summary Index for PD Quality of Life 39 (PDQ-SI). Assessments were completed at baseline (BASE), end of treatment (EOT), and 4 weeks after EOT (EOT+4).

Results

Minimal detectable change (MDC) or minimal clinical important difference (MCID) was observed in one or more outcome measures in 8 of 9 participants at EOT and EOT+4 across domains of motor function (67%, 78%), gait speed (78%, 67%), balance confidence (44%, 33%), quality of life (44%, 78%), and dynamic balance (22%, 22%). Discussion. In this case series, 8 of 9 participants showed MDC or MCID changes across multiple functional domains. Improvements were observed immediately post (EOT) and 4-week post-treatment (EOT+4) suggesting a temporal component of the LSVT-BIG impact on functional change. Future research should include clinical trials to examine additional external cueing and task-based intervention efficacy with consideration of intensity, frequency, and mode of delivery across disease severity.

Effects of STN-DBS on cognition and mood in young-onset Parkinson's disease: a two-year follow-up

BACKGROUND

The effects of subthalamic nucleus deep brain stimulation (STN-DBS) on the cognition and mood of patients with PD are still not uniformly concluded, and young-onset Parkinson's disease (YOPD) is even less explored.

OBJECTIVE

To observe the effectiveness of STN-DBS on the cognition and mood of YOPD patients.

METHODS

A total of 27 subjects, with a mean age at onset of 39.48 ± 6.24 and age at surgery for STN-DBS of 48.44 ± 4.85, were followed up preoperatively and for 2 years postoperatively. Using the Unified Parkinson disease rating scale (UPDRS), H&Y(Hoehn and Yahr stage), 39-Item Parkinson's Disease Questionnaire (PDQ-39), Mini-mental state examination (MMSE), Montreal Cognitive Assessment (MoCA), Hamilton depression scale (HAMD), Hamilton anxiety scale (HAMA) to assess motor, cognition, and mood.

RESULTS

At the 2-year follow-up after STN-DBS, YOPD patients showed significant improvements in motor and quality of life (UPDRS III: p < 0.001, PDQ-39: p < 0.001); overall cognition was not significantly different from preoperative (MMSE: p = 0.275, MoCA: p = 0.913), although language function was significantly impaired compared to preoperative (MMSE: p = 0.004, MoCA: p = 0.009); depression and anxiety symptoms also improved significantly (HAMD: p < 0.001, HAMA: p < 0.001) and the depression score correlated significantly with motor (preoperative: r = 0.493, p = 0.009), disease duration (preoperative: r = 0.519, p = 0.006; postoperative: r = 0.406, p = 0.036) and H&Y (preoperative: r = 0.430, p = 0.025; postoperative: r = 0.387, p = 0.046); total anxiety scores were also significantly correlated with motor (preoperative: r = 0.553, p = 0.003; postoperative: r = 0.444, p = 0.020), disease duration (preoperative: r = 0.417, p = 0.031), PDQ-39 (preoperative: r = 0.464, p = 0.015) and H&Y (preoperative: r = 0.440, p = 0.022; postoperative: r = 0.526, p = 0.005).

CONCLUSION

STN-DBS is a safe and effective treatment for YOPD. The mood improved significantly, and overall cognition was not impaired, were only verbal fluency decreased but did not affect the improvement in quality of life.

Serum neurofilament indicates accelerated neurodegeneration and predicts mortality in late-stage Parkinson's disease

Different stages of Parkinson's disease (PD) are defined by clinical criteria, while late-stage PD is marked by the onset of morbidity milestones and rapid clinical deterioration. Based on neuropathological evidence, degeneration in the dopaminergic system occurs primarily in the early stage of PD, raising the question of what drives disease progression in late-stage PD. This study aimed to investigate whether late-stage PD is associated with increased neurodegeneration dynamics rather than functional decompensation using the blood-based biomarker serum neurofilament light chain (sNfL) as a proxy for the rate of neurodegeneration. The study included 118 patients with PD in the transition and late-stage (minimum disease duration 5 years, mean (SD) disease duration 15 (±7) years). The presence of clinical milestones (hallucinations, dementia, recurrent falls, and admission to a nursing home) and mortality were determined based on chart review. We found that sNfL was higher in patients who presented with at least one clinical milestone and increased with a higher number of milestones (Spearman's ρ = 0.66, p < 0.001). Above a cutoff value of 26.9 pg/ml, death was 13.6 times more likely during the follow-up period (95% CI: 3.53-52.3, p < 0.001), corresponding to a sensitivity of 85.0% and a specificity of 85.7% (AUC 0.91, 95% CI: 0.85-0.97). Similar values were obtained when using an age-adjusted cutoff percentile of 90% for sNfL. Our findings suggest that the rate of ongoing neurodegeneration is higher in advanced PD (as defined by the presence of morbidity milestones) than in earlier disease stages. A better understanding of the biological basis of stage-dependent neurodegeneration may facilitate the development of neuroprotective means.

Future Directions for Developing Non-dopaminergic Strategies for the Treatment of Parkinson's Disease

The symptomatic treatment of Parkinson's disease (PD) has been dominated by the use of dopaminergic medication, but significant unmet need remains, much of which is related to non-motor symptoms and the involvement of non-dopaminergic transmitter systems. As such, little has changed in the past decades that has led to milestone advances in therapy and significantly improved treatment paradigms and patient outcomes, particularly in relation to symptoms unresponsive to levodopa. This review has looked at how pharmacological approaches to treatment are likely to develop in the near and distant future and will focus on two areas: 1) novel non-dopaminergic pharmacological strategies to control motor symptoms; and 2) novel non-dopaminergic approaches for the treatment of non-motor symptoms. The overall objective of this review is to use a 'crystal ball' approach to the future of drug discovery in PD and move away from the more traditional dopamine-based treatments. Here, we discuss promising non-dopaminergic and 'dirty drugs' that have the potential to become new key players in the field of Parkinson's disease treatment.

Setting the clinical context to non-motor symptoms reflected by Park-pain, Park-sleep, and Park-autonomic subtypes of Parkinson's disease

Non-motor symptoms (NMS) of Parkinson's disease (PD) are well described in both clinical practice and the literature, enabling their management and enhancing our understanding of PD. NMS can dominate the clinical pictures and NMS subtypes have recently been proposed, initially based on clinical observations, and later confirmed in data driven analyses of large datasets and in biomarker-based studies. In this chapter, we provide an update on what is known about three common subtypes of NMS in PD. The pain (Park-pain), sleep dysfunction (Park-sleep), and autonomic dysfunction (Park-autonomic), providing an overview of their individual classification, clinical manifestation, pathophysiology, diagnosis, and potential treatments.

Cognitive status and sleep quality can explain the fear of falling and fall history in people with Parkinson's disease

Fear of falling (FOF) is highly prevalent in people with Parkinson's disease (PwPD) and contributes to high fall risk. Studies reporting on the relationship between falls, FOF, and non-motor factors such as cognitive function and sleep quality in Parkinson's disease are limited. This study aimed to investigate (1) the relationship of cognitive function and sleep quality with FOF, and history of falls in PwPD; (2) differences in cognitive function and sleep quality between Parkinson's disease fallers and non-fallers; and (3) a cut-off score for cognitive function and sleep quality to discriminate Parkinson's disease fallers from non-fallers. Fifty PwPD were assessed for FOF [Falls Efficacy Scale-International (FES-I)], cognition [Montréal Cognitive Assessment (MOCA)], sleep quality [Pittsburgh Sleep Quality Index (PSQI)], and falls history. The MOCA is significantly associated with FES-I scores ( R2  = 0.429, P  < 0.0001). Both MOCA ( P  = 0.012) and PSQI ( P  = 0.027) were associated with falls history even after adjusting for confounding factors (age, sex, L-dopa use, Parkinson's disease severity). Both MOCA and PSQI scores were able to distinguish fallers from non-fallers with cut-off scores of 15.5 and 7.5, respectively. Although our findings revealed that both cognitive function and sleep quality are important factors influencing falls and FOF in PwPD, it remains to be determined if addressing cognitive impairments and poor sleep quality may favorably impact balance before integrating such screenings into fall prevention programs.

Peripheral MC1R Activation Modulates Immune Responses and is Neuroprotective in a Mouse Model of Parkinson's Disease

BACKGROUND

Melanocortin 1 receptor (MC1R) is a key pigmentation gene, and loss-of-function of MC1R variants that produce red hair may be associated with Parkinson's disease (PD). We previously reported compromised dopaminergic neuron survival in Mc1r mutant mice and dopaminergic neuroprotective effects of local injection of a MC1R agonist to the brain or a systemically administered MC1R agonist with appreciable central nervous system (CNS) permeability. Beyond melanocytes and dopaminergic neurons, MC1R is expressed in other peripheral tissues and cell types, including immune cells. The present study investigates the impact of NDP-MSH, a synthetic melanocortin receptor (MCR) agonist that does not cross BBB, on the immune system and the nigrostriatal dopaminergic system in mouse model of PD.

METHODS

C57BL/6 mice were treated systemically with MPTP.HCl (20 mg/kg) and LPS (1 mg/kg) from day 1 to day 4 and NDP-MSH (400 µg/kg) or vehicle from day 1 to day 12 following which the mice were sacrificed. Peripheral and CNS immune cells were phenotyped and inflammatory markers were measured. The nigrostriatal dopaminergic system was assessed behaviorally, chemically, immunologically, and pathologically. To understand the role of regulatory T cells (Tregs) in this model, CD25 monoclonal antibody was used to deplete CD25 + Tregs.

RESULTS

Systemic NDP-MSH administration significantly attenuated striatal dopamine depletion and nigral dopaminergic neuron loss induced by MPTP + LPS. It improved the behavioral outcomes in the pole test. Mc1r mutant mice injected with NDP-MSH in the MPTP and LPS paradigm showed no changes in striatal dopamine levels suggesting that the NDP-MSH acts through the MC1R pathway. Although no NDP-MSH was detected in the brain, peripheral, NDP-MSH attenuated neuroinflammation as observed by diminished microglial activation in the nigral region, along with reduced TNF-α and IL1β levels in the ventral midbrain. Depletion of Tregs was associated with diminished neuroprotective effects of NDP-MSH.

CONCLUSIONS

Our study demonstrates that peripherally acting NDP-MSH confers protection on dopaminergic nigrostriatal neurons and reduces hyperactivated microglia. NDP-MSH modulates peripheral immune responses, and Tregs may be involved in the neuroprotective effect of NDP-MSH.

Cognitive impairment and dementia in young onset Parkinson's disease

BACKGROUND AND OBJECTIVE

Patients with young-onset Parkinson's disease (YOPD) have a slower progression. Our aim was to analyze the change in cognitive function in YOPD compared to patients with a later onset and controls.

PATIENTS AND METHODS

Patients with Parkinson's disease (PD) and controls from the COPPADIS cohort were included. Cognitive function was assessed with the Parkinson's Disease Cognitive Rating Scale (PD-CRS) at baseline (V0), 2-year ± 1 month (V2y), and 4-year ± 3 months follow-up (V4y). Regarding age from symptoms onset, patients were classified as YOPD (< 50 years) or non-YOPD (≥ 50). A score in the PD-CRS < 81 was defined as cognitive impairment (CI): ≤ 64 dementia; 65-80 mild cognitive impairment (MCI).

RESULTS

One-hundred and twenty-four YOPD (50.7 ± 7.9 years; 66.1% males), 234 non-YOPD (67.8 ± 7.8 years; 59.3% males) patients, and 205 controls (61 ± 8.3 years; 49.5% males) were included. The score on the PD-CRS and its subscore domains was higher at all visits in YOPD compared to non-YOPD patients and to controls (p < 0.0001 in all analysis), but no differences were detected between YOPD patients and controls. Only non-YOPD patients had significant impairment in their cognitive function from V0 to V4y (p < 0.0001). At V4y, the frequency of dementia and MCI was 5% and 10% in YOPD compared to 25.2% and 22.3% in non-YOPD patients (p < 0.0001). A lower score on the Parkinson's Disease Sleep Scale at baseline was a predictor of CI at V4y in YOPD patients (Adjusted R2 = 0.61; OR = 0.965; p = 0.029).

CONCLUSION

Cognitive dysfunction progressed more slowly in YOPD than in non-YOPD patients.

Adopting the Rumsfeld approach to understanding the action of levodopa and apomorphine in Parkinson's disease

Dopaminergic therapies dominate the treatment of the motor and non-motor symptoms of Parkinson's disease (PD) but there have been no major advances in therapy in many decades. Two of the oldest drugs used appear more effective than others-levodopa and apomorphine-but the reasons for this are seldom discussed and this may be one cause for a lack of progress. This short review questions current thinking on drug action and looks at whether adopting the philosophy of ex-US Secretary of State Donald Rumsfeld reveals 'unknown' aspects of the actions of levodopa and apomorphine that provide clues for a way forward. It appears that both levodopa and apomorphine have a more complex pharmacology than classical views would suggest. In addition, there are unexpected facets to the mechanisms through which levodopa acts that are either forgotten as 'known unknowns' or ignored as 'unknown unknowns'. The conclusion reached is that we may not know as much as we think about drug action in PD and there is a case for looking beyond the obvious.

Impact of Safinamide on Patient-Reported Outcomes in Parkinson's Disease

Introduction

Parkinson's disease (PD) is a chronic and progressive neurodegenerative condition due to the degeneration of nigral dopaminergic cells. Both motor and non-motor symptoms (NMS) of PD produce a marked impairment in PD patients' quality of life (QoL), but contrary to motor features, NMS do not improve with dopamine replacement. Novel therapeutic interventions for PD have successfully controlled most motor manifestations of PD, but the management of NMS is still challenging. Since NMS have a negative impact on the QoL of PD patients, researchers are currently looking for drugs that can modulate the activity of neurotransmitter systems other than dopamine in the hope that can alleviate NMS in PD. Among the recently approved drugs for patients experiencing fluctuations in motor symptoms, safinamide stands out as an effective add-on therapy to levodopa. Safinamide is a monoamine oxidase type-B inhibitor (MAOB-I), with proven efficacy in reducing motor fluctuations. Its distinctive mechanism of action impacts dopaminergic pathways via MAOB inhibition and glutamatergic pathways by blocking sodium and calcium channels. Findings from Phase III clinical trials, meta-analysis, post-hoc analysis, and real-life experiences indicate that safinamide benefits motor symptoms such as tremor, bradykinesia, rigidity, and gait. Additionally, it shows promise for improving NMS like fatigue, pain, mood, and sleep disturbances in patients with PD.

Areas Covered

In this article, the authors explore the impact of safinamide on patient-reported outcomes in PD. A thorough search was conducted on PubMed focusing on studies published between 2018 and 2023 in English. The inclusion criteria encompassed clinical trials, randomized controlled trials, systematic reviews, meta-analyses, and reviews. The search strategy revolved around the implementation of MeSH terms related to safinamide and its impact on the quality of life in PD.

Conclusion

Our data strongly support the improving effect on QoL, reducing the disabling NMS reported in patients with PD.

New horizons in Parkinson's disease in older populations

Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease. Ageing is considered to be the greatest risk factor for PD, with a complex interplay between genetics and the environment. With population ageing, the prevalence of PD is expected to escalate worldwide; thus, it is of utmost importance to reduce the burden of PD. To date, there are no therapies to cure the disease, and current treatment strategies focus on the management of symptoms. Older adults often have multiple chronic diseases and geriatric syndromes, which further complicates the management of PD. Healthcare systems and care models necessary to address the broad needs of older PD patients are largely unavailable. In this New Horizon article, we discuss various aspects of PD from an ageing perspective, including disease management. We highlight recent advancements in PD therapies and discuss new care models with the potential to improve patient's quality of life.

Patient-specific models link neurotransmitter receptor mechanisms with motor and visuospatial axes of Parkinson's disease

Parkinson's disease involves multiple neurotransmitter systems beyond the classical dopaminergic circuit, but their influence on structural and functional alterations is not well understood. Here, we use patient-specific causal brain modeling to identify latent neurotransmitter receptor-mediated mechanisms contributing to Parkinson's disease progression. Combining the spatial distribution of 15 receptors from post-mortem autoradiography with 6 neuroimaging-derived pathological factors, we detect a diverse set of receptors influencing gray matter atrophy, functional activity dysregulation, microstructural degeneration, and dendrite and dopaminergic transporter loss. Inter-individual variability in receptor mechanisms correlates with symptom severity along two distinct axes, representing motor and psychomotor symptoms with large GABAergic and glutamatergic contributions, and cholinergically-dominant visuospatial, psychiatric and memory dysfunction. Our work demonstrates that receptor architecture helps explain multi-factorial brain re-organization, and suggests that distinct, co-existing receptor-mediated processes underlie Parkinson's disease.

Memory Phenotypes In Early, De Novo Parkinson's Disease Patients with Mild Cognitive Impairment

BACKGROUND

Memory deficits in mild cognitive impairment related to Parkinson's disease (PD-MCI) are quite heterogeneous, and there is no general agreement on their genesis.

OBJECTIVES

To define memory phenotypes in de novo PD-MCI and their associations with motor and non-motor features and patients' quality of life.

METHODS

From a sample of 183 early de novo patients with PD, cluster analysis was applied to neuropsychological measures of memory function of 82 patients with PD-MCI (44.8%). The remaining patients free of cognitive impairment were considered as a comparison group (n = 101). Cognitive measures and structural magnetic resonance imaging-based neural correlates of memory function were used to substantiate the results.

RESULTS

A three-cluster model produced the best solution. Cluster A (65.85%) included memory unimpaired patients; Cluster B (23.17%) included patients with mild episodic memory disorder related to a "prefrontal executive-dependent phenotype"; Cluster C (10.97%) included patients with severe episodic memory disorder related to a "hybrid phenotype," where hippocampal-dependent deficits co-occurred with prefrontal executive-dependent memory dysfunctions. Cognitive and brain structural imaging correlates substantiated the findings. The three phenotypes did not differ in terms of motor and non-motor features, but the attention/executive deficits progressively increased from Cluster A, through Cluster B, to Cluster C. This last cluster had worse quality of life compared to others.

CONCLUSIONS

Our results demonstrated the memory heterogeneity of de novo PD-MCI, suggesting existence of three distinct memory-related phenotypes. Identification of such phenotypes can be fruitful in understanding the pathophysiological mechanisms underlying PD-MCI and its subtypes and in guiding appropriate treatments. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Parkinson's Neuropathology Puzzle: A Systematic Review Uncovering the Pathological Culprits Behind the Neurological Disease

Being one of the most prevalent progressive neurodegenerative disorders (falling second only to Alzheimer's disease) with a clinical pattern affecting millions of lives all over the world, Parkinson's disease (PD) has never failed to attract a formidable interest from the vast majority of neurologists and researchers worldwide. This review article will analyze the pathophysiology, etiology, genetics, and pathological stages of Parkinson's disease with their corresponding clinical sequels. A review article was conducted using research databases including PubMed, PubMed Central, Springer, and Elsevier. The research articles reviewed using databases were written in English, German, Japanese, and Chinese and published within the preceding 50 years. Based on the article's findings, we concluded that Parkinson's disease is a progressive disorder with a variety of motor and non-motor symptoms that are influenced by a cascade of pathological neuronal abnormalities such as Lewy neurites and Lewy bodies that gradually build up with an eventual consequence of neurodegeneration of dopamine-secreting neurons. Multiple genetic mutations, pathophysiological events, and environmental factors act as the foundation to initiate that cascade.

Peripheral MC1R activation modulates immune responses and is neuroprotective in a mouse model of Parkinson's disease

Background

Melanocortin 1 receptor (MC1R) is a key pigmentation gene, and loss-of-function of MC1R variants that produce red hair may be associated with Parkinson's disease (PD). We previously reported compromised dopaminergic neuron survival in Mc1r mutant mice and dopaminergic neuroprotective effects of local injection of a MC1R agonist to the brain or a systemically administered MC1R agonist with appreciable CNS permeability. Beyond melanocytes and dopaminergic neurons, MC1R is expressed in other peripheral tissues and cell types, including immune cells. The present study investigates the impact of NDP-MSH, a synthetic melanocortin receptor (MCR) agonist that does not cross BBB, on the immune system and the nigrostriatal dopaminergic system in mouse model of PD.

Methods

C57BL/6 mice were treated systemically with MPTP.HCl (20 mg/kg) and LPS (1 mg/kg) from day 1 to day 4 and NDP-MSH (400 μg/kg) or vehicle from day 1 to day 12 following which the mice were sacrificed. Peripheral and CNS immune cells were phenotyped and inflammatory markers were measured. The nigrostriatal dopaminergic system was assessed behaviorally, chemically, immunologically, and pathologically. To understand the role of regulatory T cells (Tregs) in this model, CD25 monoclonal antibody was used to deplete CD25+ Tregs.

Results

Systemic NDP-MSH administration significantly attenuated striatal dopamine depletion and nigral dopaminergic neuron loss induced by MPTP+LPS. It improved the behavioral outcomes in the pole test. Mc1r mutant mice injected with NDP-MSH in the MPTP and LPS paradigm showed no changes in striatal dopamine levels suggesting that the NDP-MSH acts through the MC1R pathway. Although no NDP-MSH was detected in the brain, peripheral, NDP-MSH attenuated neuroinflammation as observed by diminished microglial activation in the nigral region, along with reduced TNF-α and IL1β levels in the ventral midbrain. Depletion of Tregs limited the neuroprotective effects of NDP-MSH.

Conclusions

Our study demonstrates that peripherally acting NDP-MSH confers protection on dopaminergic nigrostriatal neurons and reduces hyperactivated microglia. NDP-MSH modulates peripheral immune responses, and Tregs may be involved in the neuroprotective effect of NDP-MSH.

Chaudhuri's Dashboard of Vitals in Parkinson's syndrome: an unmet need underpinned by real life clinical tests

We have recently published the notion of the "vitals" of Parkinson's, a conglomeration of signs and symptoms, largely nonmotor, that must not be missed and yet often not considered in neurological consultations, with considerable societal and personal detrimental consequences. This "dashboard," termed the Chaudhuri's vitals of Parkinson's, are summarized as 5 key vital symptoms or signs and comprise of (a) motor, (b) nonmotor, (c) visual, gut, and oral health, (d) bone health and falls, and finally (e) comorbidities, comedication, and dopamine agonist side effects, such as impulse control disorders. Additionally, not addressing the vitals also may reflect inadequate management strategies, leading to worsening quality of life and diminished wellness, a new concept for people with Parkinson's. In this paper, we discuss possible, simple to use, and clinically relevant tests that can be used to monitor the status of these vitals, so that these can be incorporated into clinical practice. We also use the term Parkinson's syndrome to describe Parkinson's disease, as the term "disease" is now abandoned in many countries, such as the U.K., reflecting the heterogeneity of Parkinson's, which is now considered by many as a syndrome.

The noradrenergic subtype of Parkinson disease: from animal models to clinical practice

Many advances in understanding the pathophysiology of Parkinson disease (PD) have been based on research addressing its motor symptoms and phenotypes. Various data-driven clinical phenotyping studies supported by neuropathological and in vivo neuroimaging data suggest the existence of distinct non-motor endophenotypes of PD even at diagnosis, a concept further strengthened by the predominantly non-motor spectrum of symptoms in prodromal PD. Preclinical and clinical studies support early dysfunction of noradrenergic transmission in both the CNS and peripheral nervous system circuits in patients with PD that results in a specific cluster of non-motor symptoms, including rapid eye movement sleep behaviour disorder, pain, anxiety and dysautonomia (particularly orthostatic hypotension and urinary dysfunction). Cluster analyses of large independent cohorts of patients with PD and phenotype-focused studies have confirmed the existence of a noradrenergic subtype of PD, which had been previously postulated but not fully characterized. This Review discusses the translational work that unravelled the clinical and neuropathological processes underpinning the noradrenergic PD subtype. Although some overlap with other PD subtypes is inevitable as the disease progresses, recognition of noradrenergic PD as a distinct early disease subtype represents an important advance towards the delivery of personalized medicine for patients with PD.

Mood disturbances in Parkinson's disease: From prodromal origins to application of animal models

Parkinson's disease (PD) is a complex illness with a constellation of environmental insults and genetic vulnerabilities being implicated. Strikingly, many studies only focus on the cardinal motor symptoms of the disease and fail to appreciate the major non-motor features which typically occur early in the disease process and are debilitating. Common comorbid psychiatric features, notably clinical depression, as well as anxiety and sleep disorders are thought to emerge before the onset of prominent motor deficits. In this review, we will delve into the prodromal stage of PD and how early neuropsychiatric pathology might unfold, followed by later motor disturbances. It is also of interest to discuss how animal models of PD capture the complexity of the illness, including depressive-like characteristics along with motor impairment. It remains to be determined how the underlying PD disease processes contributes to such comorbidity. But some of the environmental toxicants and microbial pathogens implicated in PD might instigate pro-inflammatory effects favoring α-synuclein accumulation and damage to brainstem neurons fueling the evolution of mood disturbances. We posit that comprehensive animal-based research approaches are needed to capture the complexity and time-dependent nature of the primary and co-morbid symptoms. This will allow for the possibility of early intervention with more novel and targeted treatments that fit with not only individual patient variability, but also with changes that occur over time with the evolution of the disease.

Transcriptomic analysis: the protection of over-expression thioredoxin reductase 1 in Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disease. The pathologic characteristic feature is the loss of dopaminergic neurons in the substantia nigra (SN). However, the biochemical mechanisms are unclear. A large number of studies have shown that oxidative damage is the primary cause of PD. Hence, antioxidants could become a suitable option to treat PD. The thioredoxin (Trx) system represents a useful, potentially disease-relevant oxidation-reduction system. Thioredoxin reductase 1 (TR1) is a significant component of the Trx system.

METHODS

The overexpression lentivirus (LV) or LV-TR1 in the TR1-A53T model of PD by the stereotactic brain, and successful overexpression of LV or LV-TR1 in the MPP⁺-induced cellular model by LV or LV-TR1 transfection.

RESULTS

We confirmed that interleukin-7 mRNA levels increased in MPP⁺ compared to that in the control and MPP⁺-TR1 groups using quantitative polymerase chain reaction. The γ-H₂AX level was increased in the Tg-A53T group compared to that in the TR1-A53T group by western blotting. The expression of Na⁺-K⁺-ATP was decreased in the MPP⁺ group compared to that in the control and MPP⁺-TR1 groups by high content screening. Tg-A53T(the C57BL/6 mice transferred with mutant human a-syn); TR1-A53T(A53T mice which were injected TR1-LV 2 µl in SNc on two sides with minipump).The mice were fed for 10 months. control (the N2a cells cultivated with DMEM); MPP⁺(the N2a cells dealt with MPP⁺(1 mM) 48 h), MPP⁺-LV (the N2a cells over-expressed LV for 24 h then dealt with MPP⁺(1 mM) 48 h). MPP⁺-TR1(the N2a cell over-expressed TR1-LV for 24 h then dealt with MPP⁺(1 mM) 48 h). From the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, we confirmed that the overexpression of TR1 in SN pars compacta cells decreased oxidative stress, apoptosis, DNA damage, and inflammatory response and increased NADPH, Na⁺-K⁺-ATP, and immune response in this PD model.

CONCLUSIONS

Our study shows that overexpressed TR1 can be developed as a neuroprotective agent for PD. Therefore, our findings demonstrate a new targeted protein for the treatment of PD.

The Effects of Resistance Exercise on the Cardiorespiratory Tissue of Rats with Parkinson's Disease

Parkinson's Disease (PD) affects the cardiorespiratory system, causing an increase in the left ventricular mass in the heart and respiratory muscle weakness in relation to healthy individuals. The objective of this study was to investigate the effects of progressive resistive physical exercise on the vertical ladder on the histomorphometry of cardiac tissue and respiratory muscles in rats with PD. Seventy male Wistar rats, aged 40 days old, were divided into Parkinson's (PD) and Sham (SH) groups; they were also subdivided into groups that performed progressive resistive physical exercise on the vertical ladder Before Surgery (ExBS), After Surgery (ExAS), and Before and After Surgery (ExBAS). The physical training was carried out before and/or after PD induction. Exercise was performed five times a week for 25 min/day for four or eight weeks. PD induction was conducted via electrolytic stimulation of the Substantia nigra of the animals' brains, adopting the following stereotaxic table coordinates: -4.9; lateral medium equal to 1.7, and dorsoventral equal to 8.1. For the morphometric analysis of the heart, the following variables were calculated: relative weight and diameter and thickness of the left ventricle. The diaphragm and the myocardial, intercostal, and abdominal muscles were stained with Hematoxylin and Eosin (HE). The histomorphometric analysis was performed using the ImageJ software to assess the cross-sectional area of muscles and the number of muscle fibers. Progressive resistance exercise promoted the hypertrophy of respiratory muscles and the left ventricle in animals with PD.

Regulators of proteostasis are translationally repressed in fibroblasts from patients with sporadic and LRRK2-G2019S Parkinson's disease

Deficits in protein synthesis are associated with Parkinson's disease (PD). However, it is not known which proteins are affected or if there are synthesis differences between patients with sporadic and Leucine-Rich Repeat Kinase 2 (LRRK2) G2019S PD, the most common monogenic form. Here we used bio-orthogonal non-canonical amino acid tagging for global analysis of newly translated proteins in fibroblasts from sporadic and LRKK2-G2019S patients. Quantitative proteomic analysis revealed that several nascent proteins were reduced in PD samples compared to healthy without any significant change in mRNA levels. Using targeted proteomics, we validated which of these proteins remained dysregulated at the static proteome level and found that regulators of endo-lysosomal sorting, mRNA processing and components of the translation machinery remained low. These proteins included autophagy-related protein 9A (ATG9A) and translational stability regulator YTH N6-ethyladenosine RNA binding protein 3 (YTHDF3). Notably, 77% of the affected proteins in sporadic patients were also repressed in LRRK2-G2019S patients (False discovery rate (FDR) < 0.05) in both sporadic and LRRK2-G2019S samples. This analysis of nascent proteomes from PD patient skin cells reveals that regulators of proteostasis are repressed in both sporadic and LRRK2-G2019S PD.

Systemic Metabolic Alteration Dependent on the Thyroid-Liver Axis in Early PD

OBJECTIVE

Parkinson's disease (PD) is a common neurodegenerative disease characterized by initial involvement of the olfactory bulb/amygdala or autonomic nerves followed by nigral degeneration. Although autonomic innervation strictly regulates multiorgan systems, including endocrine functions, circulation, and digestion, how dysautonomia in PD affects systemic metabolism has not been identified. In this study, we tried to estimate the pathogenic linkage of PD by nuclear medicine techniques, trans-omic analysis of blood samples, and cultured cell experiments.

METHODS

Thyroid mediastinum ratio of ¹²³ I-metaiodobenzylguanidine (MIBG) scintigraphy was measured in 1,158 patients with PD. Furthermore, serum exosome miRNA transcriptome analysis and plasma metabolome analysis followed by trans-omic analysis were performed in patients with de novo PD and age-matched healthy control persons. Additionally, thyroid hormone was administered to skeletal muscle and liver derived cells to evaluate the effect of hypothyroidism for these organs.

RESULTS

Sympathetic denervation of thyroid correlating with its cardiac denervation was confirmed in 1,158 patients with PD by MIBG scintigraphy. Among patients with drug-naïve PD, comprehensive metabolome analysis revealed decreased levels of thyroxine and insufficient fatty acid β-oxidation, which positively correlate with one another. Likewise, both plasma metabolome data and transcriptome data of circulating exosomal miRNAs, revealed specific enrichment of the peroxisome proliferator-activated receptor (PPARα) axis. Finally, association of thyroid hormone with PPARα-dependent β-oxidation regulation was confirmed by in vitro experiments.

INTERPRETATION

Our findings suggest that interorgan communications between the thyroid and liver are disorganized in the early stage of PD, which would be a sensitive diagnostic biomarker for PD. ANN NEUROL 2023;93:303-316.

Exercise for Depressive Symptoms in Parkinson Disease: A Systematic Review and Meta-analysis of Randomized Controlled Trials

OBJECTIVE

To evaluate the efficacy of physical exercise in improving depressive symptoms in Parkinson disease (PD).

DATA SOURCE AND STUDY SELECTION

We conducted a systematic review of randomized controlled trials (RCTs) following a prespecified protocol guidance (PROSPERO CRD42021243142). Two independent authors searched for studies in MEDLINE, Cochrane Register of Controlled Trials, Physiotherapy Evidence Database, Embase, PsycINFO, and Sports Discus from database inception to June 2022.

DATA EXTRACTION

Two independent authors extracted the data and evaluated the risk of bias using the revised Cochrane risk of bias tool. We performed random-effects meta-analyses and rated the certainty of evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

DATA SYNTHESIS

A total of 36 RCTs met the inclusion criteria, 14 of which were pooled in the quantitative synthesis. Depression symptomatology significantly decreased in the exercise group compared with usual care (standardized mean difference [SMD], -0.49; 95% confidence interval [CI], -0.74 to -0.24; very low quality of evidence; 14 RCTs; 961 participants). Physical exercise also improved patients' quality of life (SMD, -0.51; 95% CI, -0.81 to -0.21; 7 RCTs; 485 participants). As for acceptability, we did not find any difference between exercise and usual care (relative risk, 1.01; 95% CI, 0.97 to 1.05; 12 RCTs; 1048 participants). We judged all the studies except 2 to be at high risk of bias.

CONCLUSIONS

Results from our systematic review identify physical activity as a viable option to reduce depressive symptoms in PD. Future clinical practice guidelines should consider physical exercise in their recommendations for depression symptomatology reduction in people with PD.

Is Disrupted Mitophagy a Central Player to Parkinson's Disease Pathology?

Whilst the pathophysiology at a cellular level has been defined, the cause of Parkinson's disease (PD) remains poorly understood. This neurodegenerative disorder is associated with impaired dopamine transmission in the substantia nigra, and protein accumulations known as Lewy bodies are visible in affected neurons. Cell culture models of PD have indicated impaired mitochondrial function, so the focus of this paper is on the quality control processes involved in and around mitochondria. Mitochondrial autophagy (mitophagy) is the process through which defective mitochondria are removed from the cell by internalisation into autophagosomes which fuse with a lysosome. This process involves many proteins, notably including PINK1 and parkin, both of which are known to be coded on genes associated with PD. Normally in healthy individuals, PINK1 associates with the outer mitochondrial membrane, which then recruits parkin, activating it to attach ubiquitin proteins to the mitochondrial membrane. PINK1, parkin, and ubiquitin cooperate to form a positive feedback system which accelerates the deposition of ubiquitin on dysfunctional mitochondria, resulting in mitophagy. However, in hereditary PD, the genes encoding PINK1 and parkin are mutated, resulting in proteins that are less efficient at removing poorly performing mitochondria, leaving cells more vulnerable to oxidative stress and ubiquitinated inclusion bodies, such as Lewy bodies. Current research that looks into the connection between mitophagy and PD is promising, already yielding potentially therapeutic compounds; until now, pharmacological support for the mitophagy process has not been part of the therapeutic arsenal. Continued research in this area is warranted.

Genetics and Pathogenesis of Parkinson's Syndrome

Parkinson's disease (PD) is clinically, pathologically, and genetically heterogeneous, resisting distillation to a single, cohesive disorder. Instead, each affected individual develops a virtually unique form of Parkinson's syndrome. Clinical manifestations consist of variable motor and nonmotor features, and myriad overlaps are recognized with other neurodegenerative conditions. Although most commonly characterized by alpha-synuclein protein pathology throughout the central and peripheral nervous systems, the distribution varies and other pathologies commonly modify PD or trigger similar manifestations. Nearly all PD is genetically influenced. More than 100 genes or genetic loci have been identified, and most cases likely arise from interactions among many common and rare genetic variants. Despite its complex architecture, insights from experimental genetic dissection coalesce to reveal unifying biological themes, including synaptic, lysosomal, mitochondrial, andimmune-mediated mechanisms of pathogenesis. This emerging understanding of Parkinson's syndrome, coupled with advances in biomarkers and targeted therapies, presages successful precision medicine strategies.

The Importance of Early Identification for Parkinson's Disease Patients with Postural Instability and Gait Disturbance

BACKGROUND

More and more evidence-based medicine has proved that Parkinson's disease (PD) patients of tremor-dominant (TD) and postural instability and gait difficulty (PIGD) subtype express great individual differences and heterogeneity. Early identification of different subtypes may be an important way to delay disease progression and improve patients' prognosis.

OBJECTIVE

The study aimed to compare the spectrum of motor symptoms (MS) and nonmotor symptoms (NMS) between TD and PIGD dominant in the early and middle stages of PD, and determine predictive factors that are associated with different motor subtypes.

METHODS

292 PD patients in this study were divided into TD-PD and PIGD-PD, and the clinical characteristics between different motor subtypes were compared based on scales related to sleep, mood, and autonomic function. Univariate and multivariate ordered logistic regression analyses were used to analyze the independent influencing factors of disease severity between different motor subtypes. Through the establishment of binary logistic regression model, the potential independent risk factors for distinguishing TD-PD and PIGD-PD were studied.

RESULTS

Compared with TD subtype, patients with PIGD subtype have longer course of disease, higher disease severity, and higher daily dosage of levodopa. The severity of nontremor motor symptoms in PIGD-PD is greater than that of TD subtype. Only PIGD score was independently associated with disease severity for the two motor subtypes. Meanwhile, high scores (LED, total UPDRS, PIGD score, gastrointestinal, thermoregulatory, RBDSQ) and low tremor scores were the potential independent risk factors for distinguishing PIGD-PD from TD-PD.

CONCLUSION

Specific nonmotor symptoms (RBD, gastrointestinal function and thermoregulation function) were associated with the PIGD subtype. Prompt detection and early treatment of NMSs related to the PIGD subtype based on the treatment of motor symptoms may improve patient outcomes.

Plasma p-tau181, neurofilament light chain and association with cognition in Parkinson’s disease

Early identification of cognitive impairment in Parkinson’s disease (PD) has important clinical and research implications. The aim of our study was to investigate the role of plasma tau phosphorylated at amino acid 181 (p-tau181) and plasma neurofilament light chain (NfL) as biomarkers of cognition in PD. Baseline concentrations of plasma p-tau181 and NfL were measured in a cohort of 136 patients with PD and 63 healthy controls (HC). Forty-seven PD patients were followed up for up to 2 years. Cross-sectional and longitudinal associations between baseline plasma biomarkers and cognitive progression were investigated using linear regression and linear mixed effects models. At baseline, plasma p-tau181 concentration was significantly higher in PD subjects compared with HC (p = 0.026). In PD patients, higher plasma NfL was associated with lower MMSE score at baseline, after adjusting for age, sex and education (p = 0.027). Baseline plasma NfL also predicted MMSE decline over time in the PD group (p = 0.020). No significant association between plasma p-tau181 concentration and baseline or longitudinal cognitive performance was found. While the role of p-tau181 as a diagnostic biomarker for PD and its relationship with cognition need further elucidation, plasma NfL may serve as a feasible, non-invasive biomarker of cognitive progression in PD.

Social decision-making in Parkinson's disease

INTRODUCTION

Parkinson's Disease (PD) commonly affects cognition and communicative functions, including the ability to perceive socially meaningful cues from nonverbal behavior and spoken language (e.g., a speaker's tone of voice). However, we know little about how people with PD use social information to make decisions in daily interactions (e.g., decisions to trust another person) and whether this ability rests on intact cognitive functions and executive/decision-making abilities in nonsocial domains.

METHOD

Non-demented adults with and without PD were presented utterances that conveyed differences in speaker confidence or politeness based on the way that speakers formulated their statement and their tone of voice. Participants had to use these speech-related cues to make trust-related decisions about interaction partners while playing the Trust Game. Explicit measures of social perception, nonsocial decision-making, and related cognitive abilities were collected.

RESULTS

Individuals with PD displayed significant differences from control participants in social decision-making; for example, they showed greater trust in game partners whose voice sounded confident and who explicitly stated that they would cooperate with the participant. The PD patients displayed relative intact social perception (speaker confidence or politeness ratings) and were unimpaired on a nonsocial decision-making task (the Dice game). No obvious relationship emerged between measures of social perception, social decision-making, or cognitive functioning in the PD sample.

CONCLUSIONS

Results provide evidence of alterations in decision-making restricted to social contexts in PD individuals with relatively preserved cognition with minimal changes in social perception. Researchers and practitioners interested in how PD affects social perception and cognition should include assessments that emulate social interactions, as non-interactive tasks may fail to detect the full impact of the disease on those affected.

Potential of Whole-Body Vibration in Parkinson’s Disease: A Systematic Review and Meta-Analysis of Human and Animal Studies

Simple Summary

Exercise has shown to have a positive impact on both motor and non-motor functions in Parkinson’s Disease patients. However, particularly in later stages of the disease, reduced cognitive function and motor capacity may lead to an inability to stay physically active. Therefore, alternative strategies for patients with Parkinson’s Disease are necessary to minimize burden for patients, their families and public health care. Whole-Body Vibration could be such an alternative. Whole-Body Vibration is an exercise or treatment method in which subjects are exposed to a mechanical vibration while sitting, standing or exercising on a vibrating platform. Whole-Body Vibration is currently used for physiotherapy, sports and rehabilitation purposes. Whole-Body Vibration treatment is interesting because it affects both the body and brain. The potential of Whole-Body Vibration for, specifically, Parkinson’s Disease patients should be clarified for further application. For this purpose, we conducted an extensive systematic review of the articles investigating the effects of Whole-Body Vibrations (1) on animals and humans with Parkinson’s Disease and (2) on neuropathological Parkinson’s Disease mechanisms. The results show some potential of Whole-Body Vibration for Parkinson’s Disease patients. The recommendations provided by this review can be used by researchers and rehabilitative practitioners implementing Whole-Body Vibration as a treatment for Parkinson’s Disease patients.

Abstract

(1) Background: When the severity of Parkinson’s Disease (PD) increases, patients often have difficulties in performing exercises. Whole-Body Vibration (WBV) may be a suitable alternative. This systematic review aims to clarify if WBV shows potential as rehabilitative therapy for PD patients. (2) Methods: We searched several databases for controlled trials investigating the effects of WBV (1) on PD populations and (2) PD neuropathological mechanisms. We included both human and animal studies and performed meta-analyses. (3) Results: The studies on PD populations (14 studies) show an overall significant, but small, effect in favor of WBV (Hedges’ g = 0.28), for which the effects on stability (Hedges’ g = 0.39) and balance (Hedges’ g = 0.30) are the most prominent. The studies on the neuropathological mechanisms (18 studies) show WBV effects on neuroinflammation (Hedges’ g = –1.12) and several specific WBV effects on neurotransmitter systems, growth factors, neurogenesis, synaptic plasticity and oxidative stress. (4) Conclusions: The effects of WBV on human PD patients remains inconclusive. Nevertheless, WBV protocols with sufficient duration (≥3 weeks), session frequency (≥3 sessions/week) and vibration frequency (≥20 Hz) show potential as a treatment method, especially for motor function. The potential of WBV for PD patients is confirmed by the effects on the neuropathological mechanisms in mostly non-PD populations. We recommend high-quality future studies on both PD patients and PD mouse models to optimize WBV protocols and to examine the neuropathological mechanisms in PD populations.

Associations of cognitive dysfunction with motor and non-motor symptoms in patients with de novo Parkinson's disease

The risk factors of mild cognitive impairment (MCI) in patients with de novo Parkinson’s disease (PD) remain unclear. Therefore, the objective of this study was to compare motor and non-motor symptoms between de novo patients with PD with and without MCI. Moreover, detailed relationships between each cognitive deficit and other clinical characteristics in de novo patients with PD were investigated. Consecutive patients with de novo PD were retrospectively enrolled in this study. Motor symptoms were assessed using the Unified Parkinson’s Disease Rating Scale (UPDRS) part-III and the Hoehn and Yahr (HY) stage. Non-motor symptoms including depression, anxiety, fatigue, and autonomic dysfunction were measured using representative questionnaires. Motor symptoms, depression, and dysautonomia were associated with MCI in de novo patients with PD. Compared with the non-MCI group with PD, the MCI group with PD had higher scores of UPDRS-III, HY stage, depression, and dysautonomia, but not fatigue or anxiety. Both UPDRS-III and HY stage were significantly linked to all cognitive deficits except attention. Logistic regression analysis showed that depression was associated with memory, visuospatial, and executive impairment, and dysautonomia was related to visuospatial and executive impairment. The results of this study suggest that cognitive impairment in PD might have a different relationship pattern to the motor and some non-motor symptoms.