Prevalence and duration of non-motor symptoms in prodromal Parkinson's disease

Vagus nerve stimulation in Parkinson's disease: a scoping review of animal studies and human subjects research

Parkinson's Disease (PD) is a prevalent, progressive neurodegenerative disease with motor and non-motor symptoms. Vagus Nerve Stimulation (VNS) has emerged as a potential therapeutic approach for PD, but published research on this topic varies widely. This scoping review maps existing literature on VNS for PD, highlighting stimulation methods, operational parameters, safety profiles, neurophysiological mechanisms, and clinical outcomes in human and animal models. Online databases were used to identify 788 papers published between 2013 and 2023, from which 17 publications on invasive and non-invasive VNS in PD were selected. Studies showed high variability in VNS parameters and study design. Evidence in animal models and human subjects suggests potential neurophysiological effects on PD-related pathology and motor function improvements. However, significant gaps in the literature remain. Future research should include rigorous reporting of study design, standardization of stimulation parameters, and larger sample sizes to ultimately facilitate translation of VNS into clinical practice.

Manganese exposure leads to depressive-like behavior through disruption of the Gln-Glu-GABA metabolic cycle

There is a correlation between long-term manganese (Mn) exposure and the Parkinson's-like disease (PD), with depression as an early symptom of PD. However, the direct relationship between Mn exposure and depression, and the mechanisms involved, remain unclear. We found that Mn exposure led to depressive-like behavior and mild cognitive impairment in mice, with Mn primarily accumulating in the cornu ammonis 3 (CA3) area of the hippocampus. Mice displayed a reduction in neuronal dendritic spines and damage to astrocytes specifically in the CA3 area. Spatial metabolomics revealed that Mn downregulated glutamic acid decarboxylase 1 (GAD1) expression in astrocytes, disrupting the Glutamine-Glutamate-γ-aminobutyric acid (GlnGluGABA) metabolic cycle in the hippocampus, leading to neurotoxicity. We established an in vitro astrocyte Gad1 overexpression (OEX) model and found that the cultured medium from Gad1 OEX astrocytes reversed neuronal synaptic damage and the expression of gamma-aminobutyric acid (GABA) related receptors. Using the astrocyte Gad1 OEX mouse model, results showed that OEX of Gad1 ameliorated depressive-like behavior and cognitive dysfunction in mice. These findings provide new insight into the important role of GAD1 mediated GlnGluGABA metabolism disorder in Mn exposure induced depressive-like behavior. This study offers a novel sight to understanding abnormal emotional states following central nervous system damage induced by Mn exposure.

Interplay between the glymphatic system and neurotoxic proteins in Parkinson's disease and related disorders: current knowledge and future directions

Parkinson's disease is a common neurodegenerative disorder that is associated with abnormal aggregation and accumulation of neurotoxic proteins, including α-synuclein, amyloid-β, and tau, in addition to the impaired elimination of these neurotoxic protein. Atypical parkinsonism, which has the same clinical presentation and neuropathology as Parkinson's disease, expands the disease landscape within the continuum of Parkinson's disease and related disorders. The glymphatic system is a waste clearance system in the brain, which is responsible for eliminating the neurotoxic proteins from the interstitial fluid. Impairment of the glymphatic system has been proposed as a significant contributor to the development and progression of neurodegenerative disease, as it exacerbates the aggregation of neurotoxic proteins and deteriorates neuronal damage. Therefore, impairment of the glymphatic system could be considered as the final common pathway to neurodegeneration. Previous evidence has provided initial insights into the potential effect of the impaired glymphatic system on Parkinson's disease and related disorders; however, many unanswered questions remain. This review aims to provide a comprehensive summary of the growing literature on the glymphatic system in Parkinson's disease and related disorders. The focus of this review is on identifying the manifestations and mechanisms of interplay between the glymphatic system and neurotoxic proteins, including loss of polarization of aquaporin-4 in astrocytic endfeet, sleep and circadian rhythms, neuroinflammation, astrogliosis, and gliosis. This review further delves into the underlying pathophysiology of the glymphatic system in Parkinson's disease and related disorders, and the potential implications of targeting the glymphatic system as a novel and promising therapeutic strategy.

Alpha Synuclein Toxicity and Non-Motor Parkinson's

Parkinson's disease (PD) is a common multisystem neurodegenerative disorder affecting 1% of the population over the age of 60 years. The main neuropathological features of PD are the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and the presence of alpha synuclein (αSyn)-rich Lewy bodies both manifesting with classical motor signs. αSyn has emerged as a key protein in PD pathology as it can spread through synaptic networks to reach several anatomical regions of the body contributing to the appearance of non-motor symptoms (NMS) considered prevalent among individuals prior to PD diagnosis and persisting throughout the patient's life. NMS mainly includes loss of taste and smell, constipation, psychiatric disorders, dementia, impaired rapid eye movement (REM) sleep, urogenital dysfunction, and cardiovascular impairment. This review summarizes the more recent findings on the impact of αSyn deposits on several prodromal NMS and emphasizes the importance of early detection of αSyn toxic species in biofluids and peripheral biopsies as prospective biomarkers in PD.

The activities of daily living partially mediate the relationship between rapid eye movement sleep behavior disorder and depressive symptoms in Parkinson's disease

Objective

A longitudinal study was conducted to investigate whether rapid eye movement sleep behavior disorder affect depression in patients with Parkinson's disease through activities of daily living.

Methods

A total of 387 Parkinson's disease patients' six-year follow-up data (one follow-up per year) were obtained from the Parkinson's Progression Markers Initiative. To allow causal effects to manifest, this study increased the lag period and divided the data from the six follow-ups into two groups: wave 1 (wave refers to time points), wave 3, and wave 5 as one group, and wave 2, wave 4, and wave6 as the other group. The time interval between two time points in each group was two years. To comprehensively and deeply analyze the dynamic relationships between variables, accurately infer causal relationships, control for individual differences, and detect the stability of these relationships, this study constructed the fixed effects cross-lagged panel model (CLPM), the random effects CLPM (RE-CLPM) model, and the Equating CLPM and Equating RE-CLPM models with applied restriction conditions. Additionally, a reverse path was added to verify the reverse prediction effect. The most suitable data analysis model was selected to explore the relationships between the study variables. Furthermore, the longitudinal mediating effect of daily living activities between rapid eye movement sleep behavior disorder and depression was investigated.

Results

In the models, Equating cross-lagged panel model was the best. The lag effect was positive and significant. In wave 1, 3, 5, activities of daily living mediated 11.82% on the path from rapid eye movement sleep behavior disorder to depression; in wave 2, 4, 6, it mediated 13.13%. Therefore, attention should be paid to the treatment of activities of daily living.

Conclusion

Longitudinal changes in activities of daily living have indirect effects on the relationship between rapid eye movement sleep behavior disorder and depression, which highlights the importance of changes in activities of daily living ability in Parkinson's disease patients with rapid eye movement sleep behavior disorder.

The Positive Effects of Physical Activity on Quality of Life in Parkinson's Disease: A Systematic Review

BACKGROUND

Physical activity can have positive effects on motor and non-motor symptoms in Parkinson's disease, but its benefits in terms of quality of life and function are uncertain and vary based on the specific forms of activities and interventions.

OBJECTIVE

We sought to assess the current evidence on the positive effects of physical activity in people with Parkinson's disease and more specifically in relation to its potential benefits for quality of life.

METHODS

This systematic review was conducted between January and April 2024 via the PubMed, Medline, and Scopus databases. Predetermined search criteria were used that included the following terms: "Parkinson's disease", "quality of life" and "physical activity".

RESULTS

A total of 1669 articles were identified. After utilizing predetermined criteria, a total of fifteen articles met the selection criteria. Statistically significant improvements in quality of life were found in seven studies. Seven studies demonstrated a significant improvement in non-motor symptoms, while nine studies showed an improvement in motor symptoms.

CONCLUSIONS

Despite heterogeneity in the study designs, interventions and clinical assessments, the articles identified in this review yielded mostly positive results in relation to physical activities. The findings reflect an improvement in motor and non-motor symptoms may translate to a better quality of life in people with Parkinson's disease.

Aging accelerates locomotor decline in PINK1 knockout rats in association with decreased nigral, but not striatal, dopamine and tyrosine hydroxylase expression

Parkinson's disease (PD) rodent models provide insight into the relationship between nigrostriatal dopamine (DA) signaling and locomotor function. Although toxin-based rat models produce frank nigrostriatal neuron loss and eventual motor decline characteristic of PD, the rapid nature of neuronal loss may not adequately translate premotor traits, such as cognitive decline. Unfortunately, rodent genetic PD models, like the Pink1 knockout (KO) rat, often fail to replicate the differential severity of striatal DA and tyrosine hydroxylase (TH) loss, and a bradykinetic phenotype, reminiscent of human PD. To elucidate this inconsistency, we evaluated aging as a progression factor in the timing of motor and non-motor cognitive impairments. Male PINK1 KO and age-matched wild type (WT) rats were evaluated in a longitudinal study from 3 to 16 months old in one cohort, and in a cross-sectional study of young adult (6-7 months) and aged (18-19 months) in another cohort. Young adult PINK1 KO rats exhibited hyperkinetic behavior associated with elevated DA and TH in the substantia nigra (SN), which decreased therein, but not striatum, in the aged KO rats. Additionally, norepinephrine levels decreased in aged KO rats in the prefrontal cortex (PFC), paired with a higher DA levels in young and aged KO. Although a younger age of onset characterizes familial forms of PD, our results underscore the critical need to consider age-related factors. Moreover, the results indicate that compensatory mechanisms may exist to preserve locomotor function, evidenced by increased DA in the SN early in the lifespan, in response to deficient PINK1 function, which declines with aging and the onset of motor decline.

PINK1 knockout rats show premotor cognitive deficits measured through a complex maze

Cognitive decline in Parkinson's disease (PD) is a critical premotor sign that may occur in approximately 40% of PD patients up to 10 years prior to clinical recognition and diagnosis. Delineating the mechanisms and specific behavioral signs of cognitive decline associated with PD prior to motor impairment is a critical unmet need. Rodent PD models that have an impairment in a cognitive phenotype for a time period sufficiently long enough prior to motor decline can be useful to establish viable candidate mechanisms. Arguably, the methods used to evaluate cognitive decline in rodent models should emulate methods used in the assessment of humans to optimize translation. Premotor cognitive decline in human PD can potentially be examined in the genetically altered PINK1-/- rat model, which exhibits a protracted onset of motor decline in most studies. To increase translation to cognitive assessment in human PD, we used a modified non-water multiple T-maze, which assesses attention, cognitive flexibility, and working memory similarly to the Trail Making Test (TMT) in humans. Similar to the deficiencies revealed in TMT test outcomes in human PD, 4-month-old PINK1-/- rats made more errors and took longer to complete the maze, despite a hyperkinetic phenotype, compared to wild-type rats. Thus, we have identified a potential methodological tool with cross-species translation to evaluate executive functioning in an established PD rat model.

The efficacy and safety of MARS-PD: Meridian activation remedy system for Parkinson's disease-A single-center, assessor and statistician-blinded, parallel-group randomized, controlled trial protocol

BACKGROUND

Parkinson's disease (PD) patients face a substantial unmet need for disease-modifying interventions. Potential approaches such as exercise and acupuncture have been investigated to slow PD progression. To address this unmet need, we developed a novel therapeutic approach that integrates acupuncture and exercise: the Meridian Activation Remedy System for PD patients (MARS-PD). Building upon promising outcomes observed in our preliminary pilot study, where MARS-PD exhibited a large clinically important difference on the Movement Disorder Society Unified Parkinson's Disease Rating Scale Part III (MDS-UPDRS Part III), we embark on a randomized controlled trial with the primary objective of examining the efficacy, safety, and economic impact of MARS-PD.

METHODS

In this single-center, assessor and statistician-blinded, parallel-group randomized controlled trial, we aim to investigate the clinical efficacy of MARS-PD through 16 interventions administered over 8 weeks in 88 PD patients. Participants will be randomly assigned to the experimental (n = 44) or control (n = 44) groups. The experimental group will receive MARS-PD intervention alongside standard care, while the control group will solely receive standard care. The intervention period spans 8 weeks, followed by a 12-week post-intervention follow-up. The primary endpoint is the change in MDS-UPDRS Part III score from baseline to the conclusion of the 8-week intervention. Secondary outcomes encompass various assessments, including MDS-UPDRS, International Physical Activity Questionnaire Short Form, Parkinson Self Questionnaire, Parkinson's Disease Sleep Scale, Timed Up and Go test, GAITRite metrics, Functional Near-Infrared Spectroscopy measurements, smart band outcomes, gut microbiome analysis results, and iris connective tissue texture.

DISCUSSION

Previous studies by the authors have indicated MARS-PD's safety and benefits for PD patients. Building upon this foundation, our current study aims to provide a more comprehensive and detailed confirmation of the efficacy of MARS-PD.

TRIAL REGISTRATION

cris.nih.go.kr KCT0006646 -First posted on 7 October 2021; ClinicalTrials.gov NCT05621772 -First posted on 11 November 2022.

Non-motor symptoms associated with progressive loss of dopaminergic neurons in a mouse model of Parkinson's disease

Parkinson's disease (PD) is characterized by three main motor symptoms: bradykinesia, rigidity and tremor. PD is also associated with diverse non-motor symptoms that may develop in parallel or precede motor dysfunctions, ranging from autonomic system dysfunctions and impaired sensory perception to cognitive deficits and depression. Here, we examine the role of the progressive loss of dopaminergic transmission in behaviors related to the non-motor symptoms of PD in a mouse model of the disease (the TIF-IADATCreERT2 strain). We found that in the period from 5 to 12 weeks after the induction of a gradual loss of dopaminergic neurons, mild motor symptoms became detectable, including changes in the distance between paws while standing as well as the swing speed and step sequence. Male mutant mice showed no apparent changes in olfactory acuity, no anhedonia-like behaviors, and normal learning in an instrumental task; however, a pronounced increase in the number of operant responses performed was noted. Similarly, female mice with progressive dopaminergic neuron degeneration showed normal learning in the probabilistic reversal learning task and no loss of sweet-taste preference, but again, a robustly higher number of choices were performed in the task. In both males and females, the higher number of instrumental responses did not affect the accuracy or the fraction of rewarded responses. Taken together, these data reveal discrete, dopamine-dependent non-motor symptoms that emerge in the early stages of dopaminergic neuron degeneration.

Metformin role in Parkinson's disease: a double-sword effect

Parkinson's disease (PD) is a common neurodegenerative disease developed due to the degeneration of dopaminergic neurons in the substantia nigra. There is no single effective treatment in the management of PD. Therefore, repurposing effective and approved drugs like metformin could be an effective strategy for managing PD. However, the mechanistic role of metformin in PD neuropathology was not fully elucidated. Metformin is an insulin-sensitizing agent used as a first-line therapy in the management of type 2 diabetes mellitus (T2DM) and has the ability to reduce insulin resistance (IR). Metformin may have a beneficial effect on PD neuropathology. The neuroprotective effect of metformin is mainly mediated by activating adenosine monophosphate protein kinase (AMPK), which reduces mitochondrial dysfunction, oxidative stress, and α-synuclein aggregation. As well, metformin mitigates brain IR a hallmark of PD and other neurodegenerative diseases. However, metformin may harm PD neuropathology by inducing hyperhomocysteinemia and deficiency of folate and B12. Therefore, this review aimed to find the potential role of metformin regarding its protective and detrimental effects on the pathogenesis of PD. The mechanistic role of metformin in PD neuropathology was not fully elucidated. Most studies regarding metformin and its effectiveness in PD neuropathology were observed in preclinical studies, which are not fully translated into clinical settings. In addition, metformin effect on PD neuropathology was previously clarified in T2DM, potentially linked to an increasing PD risk. These limitations hinder the conclusion concerning the therapeutic efficacy of metformin and its beneficial and detrimental role in PD. Therefore, as metformin does not cause hypoglycemia and is a safe drug, it should be evaluated in non-diabetic patients concerning PD risk.

Dealing with the diagnosis of Parkinson's disease and its implications for couple functioning in the early stage: An interpretative phenomenological analysis

BACKGROUND

For couples facing Parkinson's disease, marital relationships are significantly impacted, even at the early stages of the disease. However, very few studies have explicitly explored the functioning of the couple and how both partners deal with Parkinson's disease. The aim of this study was to explore the experiences and strategies of couples facing Parkinson's disease in the early stage using dyadic interpretative phenomenological analysis.

METHODS

Fifteen couples agreed to participate in the study. Semistructured interviews were conducted with each partner separately regarding his or her individual experience with Parkinson's disease, the couple's history, the impact of the diagnosis on the functioning of the couple, and his or her projections for the future.

RESULTS

Three higher-order themes emerged from the analyses. The first theme, "Being tested by the diagnosis", highlights 4 dyadic configurations according to the individual's and the couple's capacity for adjustment following the diagnosis: "noncongruent", "collapsed", "relieved" and "avoidant". The second theme, "Talking about everything except the disease", underlines that communication about the disease is often avoided both within the couple and with relatives to protect the persons with Parkinson's disease or respect their wishes. The third theme, "Supporting each other", describes the different levels of harmony between the two partners in the management of daily life and symptoms and their relational impacts.

CONCLUSION

These results allow us to better understand the experiences of both partners and to highlight the importance of promoting better acceptance of the diagnosis by persons with Parkinson's disease to allow better communication between partners and with relatives. Such support prevents disease-specific distress and facilitates better adjustment in the later stages of the disease.

Aging hastens locomotor decline in PINK1 knockout rats in association with decreased nigral, but not striatal, dopamine and tyrosine hydroxylase expression

Parkinson's disease (PD) rodent models provide insight into the relationship between nigrostriatal dopamine (DA) signaling and locomotor function. Although toxin-based rat models produce frank nigrostriatal neuron loss and eventual motor decline characteristic of PD, the rapid nature of neuronal loss may not adequately translate premotor traits, such as cognitive decline. Unfortunately, rodent genetic PD models, like the Pink1 knockout (KO) rat, often fail to replicate the differential severity of striatal DA and tyrosine hydroxylase (TH) loss, and a bradykinetic phenotype, reminiscent of human PD. To elucidate this inconsistency, we evaluated aging as a progression factor in the timing of motor and non-motor cognitive impairments. Male PINK1 KO and age-matched wild type (WT) rats were evaluated in a longitudinal study from 3 to 16 months old in one cohort, and in a cross-sectional study of young adult (6-7 months) and aged (18-19 months) in another cohort. Young adult PINK1 KO rats exhibited hyperkinetic behavior associated with elevated DA and TH in the substantia nigra (SN), which decreased therein, but not striatum, in the aged KO rats. Additionally, norepinephrine levels decreased in aged KO rats in the prefrontal cortex (PFC), paired with a higher DA content in young and aged KO. Although a younger age of onset characterizes familial forms of PD, our results underscore the critical need to consider age-related factors. Moreover, the results indicate that compensatory mechanisms may exist to preserve locomotor function, evidenced by increased DA in the SN early in the lifespan, in response to deficient PINK1 function, which declines with aging and the onset of motor impairment.

Stemming the Tide: The Proactive Role of Allied Health Therapy in Parkinson's Disease

Motor and nonmotor symptoms occur in early Parkinson's disease (PD), or even in the prodromal stage. Many of these symptoms can be addressed by allied health therapies, including physical therapy, occupational therapy, speech therapy, and psychological therapies. However, referrals to these services early in the disease are low. We provide a review summarizing the efficacy of proactive allied health interventions on motor and nonmotor symptoms and daily function in prodromal and early disease. We also highlight areas for additional research and provide recommendations to improve care for individuals with early PD within each discipline. We recognize the overlapping roles of the allied health disciplines and support integrated or transdisciplinary care beginning soon after diagnosis to help stem the tide in the progression of PD symptoms and disability.

Do Bacterial Outer Membrane Vesicles Contribute to Chronic Inflammation in Parkinson's Disease?

Parkinson's disease (PD) is an increasingly common neurodegenerative disease. It has been suggested that the etiology of idiopathic PD is complex and multifactorial involving environmental contributions, such as viral or bacterial infections and microbial dysbiosis, in genetically predisposed individuals. With advances in our understanding of the gut-brain axis, there is increasing evidence that the intestinal microbiota and the mammalian immune system functionally interact. Recent findings suggest that a shift in the gut microbiome to a pro-inflammatory phenotype may play a role in PD onset and progression. While there are links between gut bacteria, inflammation, and PD, the bacterial products involved and how they traverse the gut lumen and distribute systemically to trigger inflammation are ill-defined. Mechanisms emerging in other research fields point to a role for small, inherently stable vesicles released by Gram-negative bacteria, called outer membrane vesicles in disease pathogenesis. These vesicles facilitate communication between bacteria and the host and can shuttle bacterial toxins and virulence factors around the body to elicit an immune response in local and distant organs. In this perspective article, we hypothesize a role for bacterial outer membrane vesicles in PD pathogenesis. We present evidence suggesting that these outer membrane vesicles specifically from Gram-negative bacteria could potentially contribute to PD by traversing the gut lumen to trigger local, systemic, and neuroinflammation. This perspective aims to facilitate a discussion on outer membrane vesicles in PD and encourage research in the area, with the goal of developing strategies for the prevention and treatment of the disease.

Social deprivation and exclusion in Parkinson's disease: a cross-sectional and longitudinal study

OBJECTIVE

To describe prevalence and associated factors of social deprivation in people with Parkinson's disease (PwPD).

DESIGN

Cross-sectional and longitudinal cohort study.

SETTING

Data were taken from the Survey of Health, Ageing and Retirement in Europe (SHARE), a multidisciplinary, cross-national and longitudinal research project.

PARTICIPANTS

Community-dwelling adults from waves 5 (2013, n=66 188) and 6 (2015, n=68 186) of the SHARE dataset. After longitudinal analyses, participants in wave 5 can be retrospectively divided into the following three subgroups: PwPD at wave 5 (n=559), people newly reported PD from wave 5 to wave 6 (prodromal PD; n=215) and people without PD (n=46 737).

OUTCOME MEASURES

The prevalence and associated factors of social deprivation in PD, its impact on quality of life (QoL) and its onset within the course of PD.

RESULTS

PwPD had higher indices for material and social deprivation than non-PD participants, and 20% of PwPD were at risk of social exclusion. Social deprivation alone accounted for 35% and material deprivation for 21% of QoL variance and remained significant predictors of QoL after adjustment for cofactors. Social deprivation and risk of social exclusion were already increased in people with prodromal PD, and accordingly preceded PD diagnosis in wave 6.

CONCLUSIONS

For the treatment of PD, we should consider the impact of social deprivation and exclusion on QoL and their association with mental and physical functioning. However, the relevance of social deprivation as a prodromal phenomenon requires further investigation.

RBD and hyposmia in Moroccan patients with a synucleinopathy: prevalence and the timing of occurrence in a large cohort

INTRODUCTION

Rapid Eye Movement Sleep Behavior Disorder (RBD) and hyposmia are common in synucleinopathies and they tend to occur in connection to the prodromal development of these disorders. In this study, we sought to determine the prevalence of RBD and hyposmia and the timeline of their occurrence in a large cohort of Moroccan patients.

METHODS

We recruited 774 consecutive patients with synucleinopathy and tauopathy at Ibn Rochd University Hospital of Casablanca. A group of 100 healthy controls was also recruited. We relied on a questionnaire to collect general characteristics and clinical data filled by the patient and his companion under the supervision of a qualified health professional.

RESULTS

The study included 697 patients with PD, 37 with DLB and 40 had a tauopathy disorder (PSP or CBD). The proportion of patients who have RBD was 52% in PD, 100% in DLB, 0% in tauopathies and 12% among healthy controls. Hyposmia symptom was found in 47% of patients with PD, 68% in patients with DLB, 0% in tauopathy patients and in 10% of healthy controls. Moreover, 46% of PD patients and 75% of DLB patients developed RBD during the prodromal phase. Meanwhile, hyposmia occurred in association with the prodromal phase among 67% of PD cases and 85% of DLB patients.

CONCLUSION

RBD and hyposmia are both prevalent among Moroccan patients with synucleinopathy and they occur frequently during the prodromal phase. Identifying these premotor signs will improve early and differential diagnosis and enhance our understanding of how a specific synucleinopathy progresses.

Advances in the Diagnosis and Management of Psychotic Symptoms in Neurodegenerative Diseases: A Narrative Review

Background: Approximately 15% of older adults may experience psychotic phenomena. Primary psychiatric disorders that manifest with psychosis (delusions, hallucinations, and disorganized thought or behavior) account for less than half. Up to 60% of late-life psychotic symptoms are due to systemic medical or neurological conditions, particularly neurodegenerative diseases. A thorough medical workup including laboratory tests, additional procedures if indicated, and neuroimaging studies is recommended. This narrative review summarizes current evidence regarding the epidemiology and phenomenology of psychotic symptoms encountered as part of the neurodegenerative disease continuum (including prodromal and manifest stages). Results: Prodromes are constellations of symptoms that precede the onset of overt neurodegenerative syndromes. Prodromal psychotic features, particularly delusions, have been associated with an increased likelihood of receiving a neurodegenerative disease diagnosis within several years. Prompt prodrome recognition is crucial for early intervention. The management of psychosis associated with neurodegenerative diseases includes behavioral and somatic strategies, although evidence is scarce and mostly limited to case reports, case series, or expert consensus guidelines, with few randomized controlled trials. Conclusion: The complexity of psychotic manifestations warrants management by interprofessional teams that provide coordinated, integrated care.

Sexual dysfunction among patients with Parkinson's disease: A systematic review and meta-analysis

BACKGROUND

Previous studies have reported a higher prevalence of sexual dysfunction (SD) in patients with Parkinson's disease (PD). In the current study, we aimed to conduct a systematic review and meta-analysis to investigate the role of PD as a potential risk factor for SD in both genders.

METHODS

We performed a comprehensive search on PubMed, Embase, Scopus, and Web of Science. All observational studies comparing the prevalence of SD in PD with the general population were included.

RESULTS

After screening 22 studies were included in our qualitative and statistical analysis. We included 13 studies that reported odds ratio (OR) and found a significant association between PD and SD (pooled OR = 3.5, 95% CI = 2.19-5.58). Five studies included only male patients and reported an OR of 3.34 (95% CI = 1.34-8.35; heterogeneity I2 = 81%, Tau2 = 0.79, p < 0.00), while seven studies included both sexes and reported an OR of 3.55 (95% CI = 1.89-6.66; heterogeneity I2 = 78%, Tau2 = 0.53, p < 0.00).

CONCLUSION

In conclusion, our study suggests a strong association between PD and SD in both men and women. Our analysis of 22 observational studies reveals that the prevalence of sexual dysfunction is significantly higher in patients with PD compared to the general population. These findings highlight the importance of addressing SD as part of the comprehensive management of patients with PD.

Rehabilitation for non-motor symptoms for patients with Parkinson's disease from an α-synuclein perspective: a narrative review

Parkinson's disease (PD) is a common neurodegenerative disorder affecting aged population around the world. PD is characterized by neuronal Lewy bodies present in the substantia nigra of the midbrain and the loss of dopaminergic neurons with various motor and non-motor symptoms associated with the disease. The protein α-synuclein has been extensively studied for its contribution to PD pathology, as α-synuclein aggregates form the major component of Lewy bodies, a hallmark of PD. In this narrative review, the authors first focus on a brief explanation of α-synuclein aggregation and circumstances under which aggregation can occur, then present a hypothesis for PD pathogenesis in the peripheral nervous system (PNS) and how PD can spread to the central nervous system from the PNS via the transport of α-synuclein aggregates. This article presents arguments both for and against this hypothesis. It also presents various non-pharmacological rehabilitation approaches and management techniques for both motor and non-motor symptoms of PD and the related pathology. This review seeks to examine a possible hypothesis of PD pathogenesis and points to a new research direction focus on rehabilitation therapy for patients with PD. As various non-motor symptoms of PD appear to occur earlier than motor symptoms, more focus on the treatment of non-motor symptoms as well as a better understanding of the biochemical mechanisms behind those non-motor symptoms may lead to better long-term outcomes for patients with PD.

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.

A systematic review and meta-analysis of acupuncture in Parkinson's disease with dysphagia

Objective

The systematic review and meta-analysis aimed to comprehensively evaluate acupuncture's efficacy and safety in treating dysphagia in Parkinson's disease (PD).

Methods

We searched PubMed, Cochrane Library, Embase, Web of Science, China Knowledge Infrastructure (CNKI), China Science Journal Database (VIP), Wan-fang Database, and the China Biomedical Literature Service System (CBM) for randomized controlled trials (RCTs) comparing the efficacy of acupuncture alone or in combination with control treatment in improving dysphagia by October 2022. The degree of dysphagia was the primary outcome indicator, with secondary outcomes including serum albumin (ALB) and hemoglobin (Hb) levels, the incidence of pneumonia, and adverse events. Two investigators independently extracted information according to the inclusion and exclusion criteria. Data synthesis was calculated by RevMan (V.5.4.1) software.

Results

This study included ten randomized controlled trials with 724 patients. Most RCTs have a high or uncertain risk of bias due to the lack of a blinded design. Meta-analysis showed that acupuncture combined with control treatment was superior to control treatment alone in improving Videofluoroscopic Swallowing Study (VFSS) scores (MD: 1.48; 95% CI: 1.16, 1.81; P < 0.00001) and reducing Standardized Swallowing Assessment (SSA) scores (MD: -3.08; 95% CI: -4.01, -2.15; P < 0.00001). Acupuncture combined with control therapy has a more significant benefit in improving the clinical efficiency of dysphagia in PD (RR: 1.40; 95%CI: 1.25, 1.58; P < 0.00001). Compared to the control group without acupuncture, acupuncture improved the nutritional status of patients and increased their serum ALB (MD: 3.38, 95%CI: 1.83, 4.92, P < 0.00001) and Hb levels (MD: 7.66; 95%CI: 5.57, 9.75; P < 0.00001). Three RCTs reported that the rate of pulmonary infections in the acupuncture group was lower than without acupuncture intervention (RR: 0.29, 95% CI: 0.14, 0.63; P = 0.001).

Conclusion

Acupuncture could be recommended as an adjunctive treatment for dysphagia in PD. However, due to the high risk of bias in the included studies, more high-quality evidence is needed to confirm the efficacy and safety of acupuncture for dysphagia in PD.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022370221.

Early detection of Parkinson's disease through enriching the electronic health record using a biomedical knowledge graph

Introduction

Early diagnosis of Parkinson's disease (PD) is important to identify treatments to slow neurodegeneration. People who develop PD often have symptoms before the disease manifests and may be coded as diagnoses in the electronic health record (EHR).

Methods

To predict PD diagnosis, we embedded EHR data of patients onto a biomedical knowledge graph called Scalable Precision medicine Open Knowledge Engine (SPOKE) and created patient embedding vectors. We trained and validated a classifier using these vectors from 3,004 PD patients, restricting records to 1, 3, and 5 years before diagnosis, and 457,197 non-PD group.

Results

The classifier predicted PD diagnosis with moderate accuracy (AUC = 0.77 ± 0.06, 0.74 ± 0.05, 0.72 ± 0.05 at 1, 3, and 5 years) and performed better than other benchmark methods. Nodes in the SPOKE graph, among cases, revealed novel associations, while SPOKE patient vectors revealed the basis for individual risk classification.

Discussion

The proposed method was able to explain the clinical predictions using the knowledge graph, thereby making the predictions clinically interpretable. Through enriching EHR data with biomedical associations, SPOKE may be a cost-efficient and personalized way to predict PD diagnosis years before its occurrence.

Parkinson's Disease Risk and Hyperhomocysteinemia: The Possible Link

Parkinson's disease (PD) is one of the most common degenerative brain disorders caused by the loss of dopaminergic neurons in the substantia nigra (SN). Lewy bodies and -synuclein accumulation in the SN are hallmarks of the neuropathology of PD. Due to lifestyle changes and prolonged L-dopa administration, patients with PD frequently have vitamin deficiencies, especially folate, vitamin B6, and vitamin B12. These disorders augment circulating levels of Homocysteine with the development of hyperhomocysteinemia, which may contribute to the pathogenesis of PD. Therefore, this review aimed to ascertain if hyperhomocysteinemia may play a part in oxidative and inflammatory signaling pathways that contribute to PD development. Hyperhomocysteinemia is implicated in the pathogenesis of neurodegenerative disorders, including PD. Hyperhomocysteinemia triggers the development and progression of PD by different mechanisms, including oxidative stress, mitochondrial dysfunction, apoptosis, and endothelial dysfunction. Particularly, the progression of PD is linked with high inflammatory changes and systemic inflammatory disorders. Hyperhomocysteinemia induces immune activation and oxidative stress. In turn, activated immune response promotes the development and progression of hyperhomocysteinemia. Therefore, hyperhomocysteinemia-induced immunoinflammatory disorders and abnormal immune response may aggravate abnormal immunoinflammatory in PD, leading to more progression of PD severity. Also, inflammatory signaling pathways like nuclear factor kappa B (NF-κB) and nod-like receptor pyrin 3 (NLRP3) inflammasome and other signaling pathways are intricate in the pathogenesis of PD. In conclusion, hyperhomocysteinemia is involved in the development and progression of PD neuropathology either directly via induction degeneration of dopaminergic neurons or indirectly via activation of inflammatory signaling pathways.

Behavioural interventions for swallowing in subjects with Parkinson's disease: A mixed methods systematic review

BACKGROUND

Dysphagia is prevalent in subjects with Parkinson's disease (PD). Swallowing intervention to improve or maintain swallowing function is of major importance as dysphagia may considerably impact physical and psycho-social health.

AIMS

A mixed methods systematic review was conducted to summarize and appraise literature reporting (1) effects of behavioural interventions for swallowing in individuals with PD; and (2) participants' perspectives of swallowing interventions.

METHODS & PROCEDURES

Electronic databases were searched systematically in July 2020 for articles published between 2014 and 2020. In addition, studies published between 2000 and 2014 were identified non-systematically through previous reviews. Peer-reviewed quantitative and qualitative research in English or German documenting behavioural interventions for swallowing in individuals with a diagnosis of PD was eligible for inclusion. Participants at all disease stages were included. Behavioural interventions included rehabilitative and compensatory strategies. Studies reporting swallowing outcomes with and without a comparative group were included. For each study, the National Health and Medical Research Council level of evidence was defined. Included studies were critically appraised using the Standard Quality Assessment Criteria for Evaluating Primary Research Papers from a Variety of Fields. An integrated synthesis was performed after separate analysis of effect data and data reflecting participants' experiences. This review was conducted based on published JBI methodology and the guideline from the Preferred Reporting Items for Systematic Reviews and Meta-Analysis system was followed.

MAIN CONTRIBUTION

A total of 33 studies published in English met the inclusion criteria. Thirty-one studies reported quantitative data, one was qualitative and one was mixed methods. Intervention effects on swallowing function, swallowing safety and swallowing-related quality of life were reported for various treatment approaches. Three studies explored how participants perceived the intervention. Overriding themes including subjects' views regarding treatment schedules and levels of effort or comfort associated with the intervention were identified across these studies. Combining evidence of intervention effects and subjects' experiences was possible for one rehabilitative and one compensatory intervention.

CONCLUSIONS & IMPLICATIONS

Beneficial effects of swallowing interventions have been reported; however, most experiments were case studies of variable methodological quality. Randomized-controlled trials with robust methodology to explore treatment effects in larger samples is needed to guide clinical practice. Research reporting subjects' views is scarce. More studies exploring how individuals perceive behavioural interventions for swallowing are necessary to inform clinical decision-making.

WHAT THIS PAPER ADDS

What is already known on the subject Dysphagia is common in individuals with PD. Swallowing intervention is of major importance as dysphagia may negatively affect physical and psycho-social health of subjects with PD. What this study adds Beneficial effects of behavioural interventions for swallowing, including rehabilitative and compensatory strategies, have been reported; however, available data are mostly based on case studies of variable quality. Data on how participants perceive specific behavioural interventions are lacking. Based on the available data, integration of efficacy data and individuals' experiences is limited. What are the clinical implications of this work? Given the current evidence of intervention effects and individuals' views on behavioural treatment strategies, interventions implemented into clinical practice require careful evaluation on a case-by-case basis. More high-quality research is needed to examine interventions' short- and long-term effects in larger samples to guide clinical practice. In addition to studies evaluating intervention effects, research exploring participants' experiences with interventions is required as a foundation for clinical decision-making.

Integrated Multi-Cohort Analysis of the Parkinson's Disease Gut Metagenome

BACKGROUND

The gut microbiome is altered in several neurologic disorders, including Parkinson's disease (PD).

OBJECTIVES

The aim is to profile the fecal gut metagenome in PD for alterations in microbial composition, taxon abundance, metabolic pathways, and microbial gene products, and their relationship with disease progression.

METHODS

Shotgun metagenomic sequencing was conducted on 244 stool donors from two independent cohorts in the United States, including individuals with PD (n = 48, n = 47, respectively), environmental household controls (HC, n = 29, n = 30), and community population controls (PC, n = 41, n = 49). Microbial features consistently altered in PD compared to HC and PC subjects were identified. Data were cross-referenced to public metagenomic data sets from two previous studies in Germany and China to determine generalizable microbiome features.

RESULTS

We find several significantly altered taxa between PD and controls within the two cohorts sequenced in this study. Analysis across global cohorts returns consistent changes only in Intestinimonas butyriciproducens. Pathway enrichment analysis reveals disruptions in microbial carbohydrate and lipid metabolism and increased amino acid and nucleotide metabolism in PD. Global gene-level signatures indicate an increased response to oxidative stress, decreased cellular growth and microbial motility, and disrupted intercommunity signaling.

CONCLUSIONS

A metagenomic meta-analysis of PD shows consistent and novel alterations in functional metabolic potential and microbial gene abundance across four independent studies from three continents. These data reveal that stereotypic changes in the functional potential of the gut microbiome are a consistent feature of PD, highlighting potential diagnostic and therapeutic avenues for future research. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

SIRT1 pathway in Parkinson's disease: a faraway snapshot but so close

Silent information regulator (SIRT) has distinctive enzymatic activities and physiological functions to control cell-cycle progression, gene expression, and DNA stability by targeting histone and non-histone proteins. SIRT1 enhances synaptic formation and synaptic activity, and therefore, can reduce the progression of various degenerative brain diseases including Parkinson's disease (PD). SIRT1 activity is decreased by aging with a subsequent increased risk for the development of degenerative brain diseases. Inhibition of SIRT1 promotes inflammatory reactions since SIRT1 inhibits transcription of nuclear factor kappa B (NF-κB) which also inhibits SIRT1 activation via activation of microRNA and miR-34a which reduce NAD synthesis. SIRT1 is highly expressed in microglia as well as neurons, and has antioxidant and anti-inflammatory effects. Therefore, this review aimed to find the possible role of SIRT1 in PD neuropathology. SIRT1 has neuroprotective effects; therefore, downregulation of SIRT1 during aging promotes p53 expression and may increase the vulnerability of neuronal cell deaths. PD neuropathology is linked with the sequence of inflammatory changes and the release of pro-inflammatory cytokines due to the activation of inflammatory signaling pathways. In addition, oxidative stress, inflammatory disorders, mitochondrial dysfunction, and apoptosis contribute mutually to PD neuropathology. Thus, SIRT1 and SIRT1 activators play a crucial role in the mitigation of PD neuropathology through the amelioration of oxidative stress, inflammatory disorders, mitochondrial dysfunction, apoptosis, and inflammatory signaling pathways.

Non-motor manifestation of Parkinson's disease: a cross-sectional study in a teaching hospital in Jordan

Background

Parkinson's disease (PD) is the most common degenerative movement disorder. It is featured by motor manifestations and up till now the clinical diagnosis is based on them. Since the progress in the symptomatic treatment of PD and the longer survival of patients, non-motor manifestations (NMM) were more recognized and considered to be significant. The importance of NMM is that they reflect the more diffuse pathology of PD and may represent an opportunity of earlier diagnosis and treatment. Here in this cross-sectional study, we try to estimate the frequency of such manifestations in PD patients in the country. Using slightly modified PD non-motor (28 of 30 responses) questionnaire (NMS Quest), we studied the incidence of NMM in 100 PD patients attending one major teaching hospital and compared their occurrence in 130 age- and gender-matched non-PD controls.

Results

Out of 100 PD patients (40% females) mean age 67.4 ± 12 with disease duration of 7.3 ± 5.8, range < 1–33.2 years), and 130 control subjects (48.5% females), mean age 65.0 ± 7.0. PD patients had 8.6 ± 5.3 NMM while controls had 3.4 ± 3.3 NMM, respectively (p < 0.00001 t test). Constipation, urgency, insomnia, sad feeling, panic, light headedness and recent memory impairment were the most prevalent NMM in PD compared to controls, while nocturia, restless legs, encopresis and falling were not different in the two groups. The number of NMM ranged from 0 to 21 in PD patients with 50% having ≥ 8 manifestations. The number of NMM did not correlate with age, gender, or disease duration as defined by the classical motor symptoms. Frequency of 23 of these 28 manifestations differed significantly in PD patients compared to controls.

Conclusions

This study confirms that NMM in Jordanian PD patients are very common as reported in other populations. This signifies the universal prevalence of such NMM reflecting their important impact on their daily life and their relevant contribution to better understanding of this disease.

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.

Glymphatic System Dysfunction and Sleep Disturbance May Contribute to the Pathogenesis and Progression of Parkinson’s Disease

Parkinson’s disease (PD) is a multisystem alpha-synucleinopathic neurodegenerative disease and the most prevalent neurodegenerative disorder after Alzheimer’s disease with a high incidence rate in the elderly population. PD is highly multifactorial in etiology and has complex and wide-ranging pathogenic mechanisms. Environmental exposures and genetic predisposition are prominent risk factors. However, current evidence suggests that an intimate link may exist between the risk factor of sleep disturbance and PD pathogenesis. PD is characterized by the pathological hallmarks of alpha-synuclein aggregations and dopaminergic neuron degeneration in the substantia nigra. The loss of dopamine-producing neurons results in both motor and non-motor symptoms, most commonly, bradykinesia, tremor, rigidity, psychiatric disorders, sleep disorders and gastrointestinal problems. Factors that may exacerbate alpha-synuclein accumulation and dopamine neuron loss include neuroinflammation and glymphatic system impairment. Extracellular alpha-synuclein can induce an inflammatory response which can lead to neural cell death and inhibition of neurogenesis. The glymphatic system functions most optimally to remove extracellular brain solutes during sleep and therefore sleep disruption may be a crucial progression factor as well as a risk factor. This literature review interprets and analyses data from experimental and epidemiological studies to determine the recent advances in establishing a relationship between glymphatic system dysfunction, sleep disturbance, and PD pathogenesis and progression. This review addresses current limitations surrounding the ability to affirm a causal link between improved glymphatic clearance by increased sleep quality in PD prevention and management. Furthermore, this review proposes potential therapeutic approaches that could utilize the protective mechanism of sleep, to promote glymphatic clearance that therefore may reduce disease progression as well as symptom severity in PD patients.

Propolis induces cardiac metabolism changes in 6-hydroxydopamine animal model: A dietary intervention as a potential cardioprotective approach in Parkinson’s disease

While there is sustained growth of the older population worldwide, ageing is a consistent risk factor for neurodegenerative diseases, such as Parkinson’s-disease (PD). Considered an emblematic movement disorder, PD comprises a miscellany of non-motor symptoms, for which effective management remains an unfulfilled need in clinical practice. Highlighted are the cardiovascular abnormalities, that cause significant burden in PD patients. Evidence suggests that key biological processes underlying PD pathophysiology can be modulated by diet-derived bioactive compounds, such as green propolis, a natural functional food with biological and pharmacological properties. The effects of propolis on cardiac affection associated to PD have received little coverage. In this study, a metabolomics approach and Positron Emission Tomography (PET) imaging were used to assess the metabolic response to diet supplementation with green propolis on heart outcomes of rats with Parkinsonism induced by 6-hydroxydopamine (6-OHDA rats). Untargeted metabolomics approach revealed four cardiac metabolites (2-hydroxybutyric acid, 3-hydroxybutyric acid, monoacylglycerol and alanine) that were significantly modified between animal groups (6-OHDA, 6-OHDA + Propolis and sham). Propolis-induced changes in the level of these cardiac metabolites suggest beneficial effects of diet intervention. From the metabolites affected, functional analysis identified changes in propanoate metabolism (a key carbohydrate metabolism related metabolic pathway), glucose-alanine cycle, protein and fatty acid biosynthesis, energy metabolism, glutathione metabolism and urea cycle. PET imaging detected higher glucose metabolism in the 17 areas of the left ventricle of all rats treated with propolis, substantially contrasting from those rats that did not consume propolis. Our results bring new insights into cardiac metabolic substrates and pathways involved in the mechanisms of the effects of propolis in experimental PD and provide potential novel targets for research in the quest for future therapeutic strategies.

Neuroprotective Function of Rasagiline and Selegiline, Inhibitors of Type B Monoamine Oxidase, and Role of Monoamine Oxidases in Synucleinopathies

Synucleinopathies are a group of neurodegenerative disorders caused by the accumulation of toxic species of α-synuclein. The common clinical features are chronic progressive decline of motor, cognitive, behavioral, and autonomic functions. They include Parkinson’s disease, dementia with Lewy body, and multiple system atrophy. Their etiology has not been clarified and multiple pathogenic factors include oxidative stress, mitochondrial dysfunction, impaired protein degradation systems, and neuroinflammation. Current available therapy cannot prevent progressive neurodegeneration and “disease-modifying or neuroprotective” therapy has been proposed. This paper presents the molecular mechanisms of neuroprotection by the inhibitors of type B monoamine oxidase, rasagiline and selegiline. They prevent mitochondrial apoptosis, induce anti-apoptotic Bcl-2 protein family, and pro-survival brain- and glial cell line-derived neurotrophic factors. They also prevent toxic oligomerization and aggregation of α-synuclein. Monoamine oxidase is involved in neurodegeneration and neuroprotection, independently of the catalytic activity. Type A monoamine oxidases mediates rasagiline-activated signaling pathways to induce neuroprotective genes in neuronal cells. Multi-targeting propargylamine derivatives have been developed for therapy in various neurodegenerative diseases. Preclinical studies have presented neuroprotection of rasagiline and selegiline, but beneficial effects have been scarcely presented. Strategy to improve clinical trials is discussed to achieve disease-modification in synucleinopathies.

Apathy in Parkinson's Disease: Defining the Park Apathy Subtype

Apathy is a neurobehavioural symptom affecting Parkinson's disease patients of all disease stages. Apathy seems to be associated with a specific underlying non-motor disease subtype and reflects dysfunction of separate neural networks with distinct neurotransmitter systems. Due to the complicated neuropsychiatric aetiology of apathy, clinical assessment of this invalidating non-motor symptom remains challenging. We aim to summarize the current findings on apathy in Parkinson's disease and highlight knowledge gaps. We will discuss the prevalence rates across the different disease stages and suggest screening tools for clinically relevant apathetic symptoms. We will approach the fundamental knowledge on the neural networks implicated in apathy in a practical manner and formulate recommendations on patient-tailored treatment. We will discuss the Park apathy phenotype in detail, shedding light on different clinical manifestations and implications for prognosis. With this review, we strive to distil the vast available theoretical knowledge into a clinical and patient-oriented perspective.

Dietary interventions in Parkinson’s disease: An update

Parkinson’s disease (PD) is a progressive neurodegenerative disorder mostly affecting the elderly population. Nutritional status, dietary habits, and physical activity are closely associated with PD clinical symptoms. Based on scientific evidence, lifestyle adjustments are being considered as therapy approaches in various chronic diseases. Dietary modifications are an additional treatment strategy for managing motor and non-motor symptoms in PD. This review focuses on the latest nutritional interventions with protein restriction, Mediterranean and ketogenic dietary modification, probiotic utilisation, and their impact on PD.

Associations of Sleep Disorders With Depressive Symptoms in Early and Prodromal Parkinson's Disease

Background

Non-motor symptoms, including sleep disorders and depression, are common in Parkinson’s disease (PD). The purpose of our study is to explore the effect of sleep disorders, including the probable rapid eye movement (REM) sleep behavior disorder (pRBD) and the daytime sleepiness, on depressive symptoms in patients with early and prodromal PD.

Methods

A total of 683 participants who obtained from the Parkinson Progression Markers Initiative (PPMI) were included, consisting of 423 individuals with early PD, 64 individuals with prodromal PD, and 196 healthy controls (HCs), who were followed up to 5 years from baseline. Multiple linear regression models and linear mixed-effects models were conducted to explore the relationship between sleep disorders and depression at baseline and longitudinally, respectively. Multiple linear regression models were used to further investigate the association between the change rates of daytime sleepiness score and depression-related score. Mediation analyses were also performed.

Results

At baseline analysis, individuals with early and prodromal PD, who had higher RBD screening questionnaire (RBDSQ) score, or who were considered as pRBD, or who manifested specific behaviors of RBD (things falling down when sleep or disturbance of sleep), showed significantly the higher score of depression-related questionnaires. Our 5-year follow-up study showed that sleep disorders, including pRBD and daytime sleepiness, were associated with the increased depressive-related score in individuals with early and prodromal PD. Interestingly, we also found that the increased possibilities of daytime sleepiness were associated with depressive-related score. Finally, mediation analysis demonstrated that the relationship between RBD and depressive symptoms was partially mediated by autonomic symptoms, such as postural hypertension, salivation, dysphagia, and constipation.

Conclusion

Our study shows that sleep disorders, including pRBD and daytime sleepiness, are associated with depression at baseline and longitudinally, which is partially mediated by the autonomic dysfunction in early and prodromal PD, with an implication that sleep management is of great value for disease surveillance.

Prion-like α-synuclein pathology in the brain of infants with Krabbe disease

Krabbe disease is an infantile neurodegenerative disorder resulting from pathogenic variants in the GALC gene that causes accumulation of the toxic sphingolipid psychosine. GALC variants are also associated with Lewy body diseases, an umbrella term for age-associated neurodegenerative diseases in which the protein α-synuclein aggregates into Lewy bodies. To explore whether α-synuclein in Krabbe disease has pathological similarities to that in Lewy body disease, we performed an observational post-mortem study of Krabbe disease brain tissue (n = 4) compared to infant controls (n = 4) and identified widespread accumulations of α-synuclein. To determine whether α-synuclein in Krabbe disease brain displayed disease-associated pathogenic properties we evaluated its seeding capacity using the real-time quaking-induced conversion assay in two cases for which frozen tissue was available and strikingly identified aggregation into fibrils similar to those observed in Lewy body disease, confirming the prion-like capacity of Krabbe disease-derived α-synuclein. These observations constitute the first report of prion-like α-synuclein in the brain tissue of infants and challenge the putative view that α-synuclein pathology is merely an age-associated phenomenon, instead suggesting it results from alterations to biological pathways, such as sphingolipid metabolism. Our findings have important implications for understanding the mechanisms underlying Lewy body formation in Lewy body disease.

The Gut Microbiome in Parkinson's Disease: A Longitudinal Study of the Impacts on Disease Progression and the Use of Device-Assisted Therapies

Background

Altered gut microbiome (GM) composition has been established in Parkinson's disease (PD). However, few studies have longitudinally investigated the GM in PD, or the impact of device-assisted therapies.

Objectives

To investigate the temporal stability of GM profiles from PD patients on standard therapies and those initiating device-assisted therapies (DAT) and define multivariate models of disease and progression.

Methods

We evaluated validated clinical questionnaires and stool samples from 74 PD patients and 74 household controls (HCs) at 0, 6, and 12 months. Faster or slower disease progression was defined from levodopa equivalence dose and motor severity measures. 19 PD patients initiating Deep Brain Stimulation or Levodopa-Carbidopa Intestinal Gel were separately evaluated at 0, 6, and 12 months post-therapy initiation.

Results

Persistent underrepresentation of short-chain fatty-acid-producing bacteria, Butyricicoccus, Fusicatenibacter, Lachnospiraceae ND3007 group, and Erysipelotrichaceae UCG-003, were apparent in PD patients relative to controls. A sustained effect of DAT initiation on GM associations with PD was not observed. PD progression analysis indicated that the genus Barnesiella was underrepresented in faster progressing PD patients at t = 0 and t = 12 months. Two-stage predictive modeling, integrating microbiota abundances and nutritional profiles, improved predictive capacity (change in Area Under the Curve from 0.58 to 0.64) when assessed at Amplicon Sequence Variant taxonomic resolution.

Conclusion

We present longitudinal GM studies in PD patients, showing persistently altered GM profiles suggestive of a reduced butyrogenic production potential. DATs exerted variable GM influences across the short and longer-term. We found that specific GM profiles combined with dietary factors improved prediction of disease progression in PD patients.

Prevalence, clinical presentations and impact on relationship of sexual dysfunction in Parkinson's Disease

Sexual dysfunction is one of the commonest non-motor symptoms in Parkinson's disease (PD) and has been found about twice as high in PD patients compared to age-matched controls. The quality of sexual life is reduced in PD patients compared to healthy peers and impairment affects wide aspects of physical sexual function as well as sexual desire, sexual satisfaction and sexual partnership. Overall, male PD patients are more frequently affected by sexual disorders than females and seem to suffer more from sexual impairment. The reported frequencies and presentations of various sexual dysfunctions vary widely in the literature, which is likely related to the patient cohorts examined, in particular with regard to age and gender, duration and severity of disease and applied measurement instruments. This chapter gives an overview of the prevalence, phenotype and clinical presentation of sexual dysfunction in PD and its influence on the partnership.

Pathophysiology and Symptomatology of Drooling in Parkinson’s Disease

Drooling can present in patients with Parkinson’s disease (PD), and it is manifested as an excessive pooling of saliva inside the oral cavity. Currently, the exact pathophysiological mechanism of drooling in PD is not yet fully explicated. Thus, it becomes crucial to understand if some clinical characteristics may emphasize drooling or if they are just concomitant. In PD, excessive drooling has been associated with a higher burden of non-motor symptoms, such as cognitive impairment, sleep problems, autonomic dysfunction, constipation and orthostatic hypotension, and of worse severity of motor fluctuations and bradykinesia. PD patients with excessive drooling also showed a reduction of striatal DAT availability at DaTSCAN imaging. Excessive drooling in patients with Parkinson’s cannot be attributed to a single factor but to a mixture of factors, including but not limited to impaired nigrostriatal pathways.

Self-Reported Visual Complaints in People with Parkinson's Disease: A Systematic Review

BACKGROUND

Scientific research increasingly focuses on visual symptoms of people with Parkinson's disease (PD). However, this mostly involves functional measures, whereas self-reported data are equally important for guiding clinical care.

OBJECTIVE

This review provides an overview of the nature and prevalence of self-reported visual complaints by people with PD, compared to healthy controls.

METHODS

A systematic literature search was performed. Studies from three databases (PubMed, PsycInfo, and Web of Science) were screened for eligibility. Only studies that reported results of visual self-reports in people with idiopathic PD were included.

RESULTS

One hundred and thirty-nine eligible articles were analyzed. Visual complaints ranged from function-related complaints (e.g., blurred vision, double vision, increased sensitivity to light or changes in contrast sensitivity) to activity-related complaints (e.g., difficulty reading, reaching, or driving). Visual complaints were more prevalent in people with PD compared to healthy controls. The presence of visual complaints leads to a reduced quality of life (QoL). Increased prevalence and severity of visual complaints in people with PD are related to longer disease duration, higher disease severity, and off-state.

CONCLUSION

A large proportion of people with PD have visual complaints, which negatively affect QoL. Complaints are diverse in nature, and specific and active questioning by clinicians is advised to foster timely recognition, acknowledgement, and management of these complaints.

Immunisation with UB-312 in the Thy1SNCA mouse prevents motor performance deficits and oligomeric α-synuclein accumulation in the brain and gut

Alpha synuclein has a key role in the pathogenesis of Parkinson's disease (PD), Dementia with Lewy Bodies (LBD) and Multiple System Atrophy (MSA). Immunotherapies aiming at neutralising toxic αSyn species are being investigated in the clinic as potential disease modifying therapies for PD and other synucleinopathies. In this study, the effects of active immunisation against αSyn with the UB-312 vaccine were investigated in the Thy1SNCA/15 mouse model of PD. Young transgenic and wild-type mice received an immunisation regimen over a period of 6 weeks, then observed for an additional 9 weeks. Behavioural assessment was conducted before immunisation and at 15 weeks after the first dose. UB-312 immunisation prevented the development of motor impairment in the wire test and challenging beam test, which was associated with reduced levels of αSyn oligomers in the cerebral cortex, hippocampus and striatum of Thy1SNCA/15 mice. UB-312 immunotherapy resulted in a significant reduction of theαSyn load in the colon, accompanied by a reduction in enteric glial cell reactivity in the colonic ganglia. Our results demonstrate that immunisation with UB-312 prevents functional deficits and both central and peripheral pathology in Thy1SNCA/15 mice.

Premature cognitive decline in specific domains found in young veterans with mTBI coincide with elder normative scores and advanced-age subjects with early-stage Parkinson's disease

Importance

Epidemiologists report a 56% increased risk of veterans with (+) mild traumatic brain injury (mTBI) developing Parkinson’s disease (PD) within 12-years post-injury. The most relevant contributors to this high risk of PD in veterans (+) mTBI is unknown. As cognitive problems often precede PD diagnosis, identifying specific domains most involved with mTBI-related PD onset is critical.

Objectives

To discern which cognitive domains underlie the mTBI-PD risk relationship proposed in epidemiology studies.

Design and setting

This exploratory match-controlled, cross-sectional study was conducted in a medical school laboratory from 2017–2020.

Participants

Age- and IQ-matched veterans with (+) and without mTBI, non-veteran healthy controls, and IQ-matched non-demented early-stage PD were compared. Chronic neurological, unremitted/debilitating diseases, disorders, dementia, and substance use among others were excluded.

Exposure

Veterans were or were not exposed to non-penetrating combat-related mTBI occurring within the past 7-years. No other groups had recent military service or mTBI.

Main outcomes / measures

Cognitive flexibility, attention, memory, visuospatial ability, and verbal fluency were examined with well-known standardized neuropsychological assessments.

Results

Out of 200 volunteers, 114 provided evaluable data. Groups significantly differed on cognitive tests [F (21,299) = 3.09, p<0.0001]. Post hoc tests showed veterans (+) mTBI performed significantly worse than matched-control groups on four out of eight cognitive tests (range: p = .009 to .049), and more often than not performed comparably to early-stage PD (range: p = .749 to .140).

Conclusions and relevance

We found subtle, premature cognitive decline occurring in very specific cognitive domains in veterans (+) mTBI that would typically be overlooked in a clinic setting, This result potentially puts them at-risk for continual cognitive decline that may portend to the eventual onset of PD or some other neurodegenerative disease.

Sexual Dysfunction in Early-Onset Parkinson's Disease: A Cross-Sectional, Multicenter Study

BACKGROUND

Sexual dysfunction (SD) is one of the least studied non-motor symptoms in Parkinson's disease (PD).

OBJECTIVES

To assess sexual function in a cohort of patients with early-onset PD (EOPD) and compare it to a group of healthy controls.

METHODS

In this cross-sectional multicenter study, SD was assessed with gender-specific multi-dimensional self-reported questionnaires: The Brief Male Sexual Function Inventory (BSFI-M) and the Female Sexual Function Index (FSFI). Scores between patients and controls were compared and associations between SD and demographical and clinical variables were studied.

RESULTS

One hundred and five patients (mean age 47.35±7.8, disease duration 6 (3-11) years, UPDRS part III 17 (10-23) and 90 controls were recruited. The BSFI-M total score was lower in EOPD men than in controls, and specific items were also significantly lower, such as drive, erections, ejaculation, and satisfaction. EOPD women had lower scores than controls in totalFSFI, and certain domains such as lubrication and pain. SD was present in 70.2% of patients and 52.5% of controls. Sexual satisfaction in 35.2% of patients and 81.2% of controls. By gender, male and female patients had more SD than controls but only male patients had more dissatisfaction than controls. Gender, higher depression scores and urinary dysfunction were associated with SD in multivariate analysis; and gender, UPDRS and urinary dysfunction with sexual satisfactionConclusion:In this Spanish cohort, SD and sexual dissatisfaction was more prevalent in EOPD patients than in the general population. Gender and urinary disfunction were associated with SD and sexual dissatisfaction.

Heterogeneity of prodromal Parkinson symptoms in siblings of Parkinson disease patients

A prodromal phase of Parkinson's disease (PD) may precede motor manifestations by decades. PD patients' siblings are at higher risk for PD, but the prevalence and distribution of prodromal symptoms are unknown. The study objectives were (1) to assess motor and non-motor features estimating prodromal PD probability in PD siblings recruited within the European PROPAG-AGEING project; (2) to compare motor and non-motor symptoms to the well-established DeNoPa cohort. 340 PD siblings from three sites (Bologna, Seville, Kassel/Goettingen) underwent clinical and neurological evaluations of PD markers. The German part of the cohort was compared with German de novo PD patients (dnPDs) and healthy controls (CTRs) from DeNoPa. Fifteen (4.4%) siblings presented with subtle signs of motor impairment, with MDS-UPDRS-III scores not clinically different from CTRs. Symptoms of orthostatic hypotension were present in 47 siblings (13.8%), no different to CTRs (p = 0.072). No differences were found for olfaction and overall cognition; German-siblings performed worse than CTRs in visuospatial-executive and language tasks. 3/147 siblings had video-polysomnography-confirmed REM sleep behavior disorder (RBD), none was positive on the RBD Screening Questionnaire. 173/300 siblings had <1% probability of having prodromal PD; 100 between 1 and 10%, 26 siblings between 10 and 80%, one fulfilled the criteria for prodromal PD. According to the current analysis, we cannot confirm the increased risk of PD siblings for prodromal PD. Siblings showed a heterogeneous distribution of prodromal PD markers and probability. Additional parameters, including strong disease markers, should be investigated to verify if these results depend on validity and sensitivity of prodromal PD criteria, or if siblings' risk is not elevated.

Onset of Skin, Gut, and Genitourinary Prodromal Parkinson's Disease: A Study of 1.5 Million Veterans

BACKGROUND

Prodromal Parkinson's disease of skin, genitourinary, and gastrointestinal systems offers a unique window for understanding early disease pathogenesis and developing disease modifying treatments. However, prior studies are limited by incomplete timing information, small sample size, and lack of adjustment for known confounders. Verifying prodromal timing and identifying new disorders in these accessible organs is critically important given their broad use.

OBJECTIVE

We aimed to measure onset timing for gastrointestinal, genitourinary, and skin disorders in a large, nationwide clinically characterized cohort of 1.5 million participants.

METHODS

Patients with Parkinson's disease (n = 303,693) were identified using diagnostic codes in the medical records database of the United States Veterans Affairs healthcare system and were compared 4:1 with matched controls. Disorder prevalence and estimated onset times were assessed for 20 years preceding diagnosis.

RESULTS

The earliest significantly increased prodromal disorders were gastroesophageal reflux, sexual dysfunction, and esophageal dyskinesia at 17, 16, and 15 years before diagnosis. Estimated onset times for each disorder occurred 5.5 ± 3.4 years before the first measured increase. The earliest estimated onset times were smell/taste, upper gastrointestinal tract, and sexual dysfunction at 20.9, 20.6, and 20.1 years before diagnosis. Onset times for constipation and urinary dysfunction were notably longer by 7 and 9 years compared to prior studies in sleep disorder patients. Dermatophytosis and prostatic hypertrophy were identified as new high prevalence prodromal disorders.

CONCLUSIONS

Gastrointestinal, genitourinary, and skin disorders manifest decades before diagnosis of Parkinson's disease, reiterating their potential as sites for developing early diagnostic testing and understanding pathogenesis.

Probing the Pre-diagnostic Phase of Parkinson's Disease in Population-Based Studies

Parkinson's disease covers a wide spectrum of symptoms, ranging from early non-motor symptoms to the characteristic bradykinesia, tremor and rigidity. Although differences in the symptomatology of Parkinson's disease are increasingly recognized, there is still a lack of insight into the heterogeneity of the pre-diagnostic phase of Parkinson's disease. In this perspective, we highlight three aspects regarding the role of population-based studies in providing new insights into the heterogeneity of pre-diagnostic Parkinson's disease. First we describe several specific advantages of population-based cohort studies, including the design which overcomes some common biases, the broad data collection and the high external validity. Second, we draw a parallel with the field of Alzheimer's disease to provide future directions to uncover the heterogeneity of pre-diagnostic Parkinson's disease. Finally, we anticipate on the emergence of prevention and disease-modification trials and the potential role of population-based studies herein. In the coming years, bridging gaps between study designs will be essential to make vital advances in elucidating the heterogeneity of pre-diagnostic Parkinson's disease.

Comparison in detection of prodromal Parkinson's disease patients using original and updated MDS research criteria in two independent cohorts

INTRODUCTION

MDS research criteria for prodromal Parkinson's disease (pPD) were published in 2015 and updated in 2019. We aimed to determine the difference in pPD patient detection rates in two cohorts recruited via gastrointestinal symptoms (PARCAS study) and the presence of a probable REM sleep behaviour disorder (PDBIOM study) using the original and updated criteria.

METHODS

We evaluated all risk and prodromal markers, except genetic testing, plasma urate and physical inactivity, in both cohorts and DaT scan, diabetes mellitus type II and cognitive deficit in the PARCAS cohort. Thresholds of 50% probability for possible pPD and 80% for probable pPD were used.

RESULTS

PPD status as identified by the original/updated criteria showed differences for probable pPD (n = 8/9; original/updated criteria) and possible pPD (n = 9/13) in the PARCAS cohort (total n = 158), as well as for probable pPD (n = 19/21) and possible pPD (n = 6/3) in the PDBIOM cohort (total n = 48). A high concordance rate was found between the two criteria sets (p < 0.001 for all groups).

CONCLUSION

All probable pPD cases remained in the same category after evaluation with both criteria; three possible pPD cases based on the original criteria exceeded the threshold for probable pPD based on the updated criteria, and five possible new pPD cases were detected, with only one shift in the opposite direction. The updated MDS pPD research criteria tend to identify more patients as positive, yet their accuracy needs to be determined in prospective studies.