Autonomic dysfunction in Parkinson's disease: Implications for pathophysiology, diagnosis, and treatment

Autonomic Function in Parkinson's Disease Subjects Across Repeated Short-Term Dry Immersion: Evidence From Linear and Non-linear HRV Parameters

Several studies have shown that “dry” immersion appears as a promising method of rehabilitation for Parkinson's disease. Still, little is known about the cardiovascular reaction in “dry” immersion (DI), especially in Parkinson's disease (PD). Therefore, this study was aimed to evaluate the effect of repeated 45-min DI sessions on autonomic function in subjects with PD. The study group consisted of 20 subjects with PD [13 men, seven women, aged 51–66 years old, Hoehn & Yahr (H&Y) staged 1–3] were enrolled in the study according to inclusion and non-inclusion criteria. The DI program was comprised of seven 45-min DI sessions, applied within 25–30 days. Blood pressure (BP), heart rate (HR), and electrocardiogram (ECG) in the standard lead II were recorded at 1st, 4th, and 7th DI, before, on the 15, 30, and 40th min of DI session. Autonomic function was assessed with analysis of heart rate variability (HRV) using Kubios Standard version 2 software. Linear (time- and frequency-domain) and non-linear (correlation dimension, entropies, DFA1 and DFA2, percent of determinism, and recurrence) were computed. At baseline condition, time- and frequency-domain HRV parameters showed low variability of HR, which indicates reduced autonomic neurogenic control of HR. Throughout the DI session, systolic and diastolic BP has decreased by 5–7 mm Hg (p < 0.001), and time- and frequency-domain parameters of HRV have significantly increased, what can be regarded as compensatory mechanisms of hemodynamics during DI. The structure of the regulatory input to the heart seen by HRV was characterized by low complexity and reduced autonomic neurogenic control of HR. Across the program of DI sessions, the hypotensive effect was documented, but no notable modification of the HRV-parameters was found. The absence of long-term modification of the studied parameters can be attributed both to deconditioning environmental effect of DI and limited adaptation of the organism due to neurodegeneration in PD. That should be taken into consideration when planning rehabilitation measures in subjects of older age and chronic somatic diseases with modeled microgravity.

Analysis of pupillometer results according to disease stage in patients with Parkinson's disease

We performed pupillometer testing on 132 patients with Parkinson’s disease, stratified into two groups according to the disease stage. Neurological examinations and pupillometry were performed in the ON state. Patients in the Hoehn and Yahr stages 1 and 2 comprised the early group, and patients in stages 3–5 formed the late group. We performed age- and sex-matched (2:1) propensity score matching to compensate for the effect of age on pupil light reflex. Eight pupillometer parameters were measured and compared between the two groups. After the propensity score matching, the early group had 64 patients and the late group had 32 patients. The late group had a longer disease duration and took a higher levodopa equivalent dose than the early group. The constriction velocity (P = 0.006) and maximum constriction velocity (P = 0.005) were significantly faster in the early group than in the late group. Pupil size, minimum diameter, and dilation velocity were similar in both groups. The pupillary contraction velocity decreased with the disease progression, suggesting that the progression of Parkinson’s disease could be identified by the pupil constriction velocity.

Diabetes Mellitus and Parkinson's Disease: A Systematic Review and Meta-Analyses

BACKGROUND

A link between diabetes mellitus (DM) and Parkinson's disease (PD) have been proposed but evidence are sparse and inconsistent.

OBJECTIVE

Perform a systematic review of all evidence that link DM and PD characterising the prevalence of DM in PD patients, the risk of developing PD in DM patients and the influence of DM on PD severity and progression.

METHODS

MEDLINE, Scopus, and Cochrane Library from inception to June 30, 2021 were searched. Studies reporting prevalence, incidence, severity and disease progression of DM and PD were included. Prevalence of DM in PD and incidence of PD in DM patients, and characteristics of PD.

RESULTS

A total of 21 studies (n = 11,396) included data on DM prevalence in PD patients, 12 studies (n = 17,797,221) included data on incidence of PD in DM patients, and 10 studies (n = 2,482) included data on DM impact on PD severity and disease progression. The prevalence of DM in PD patients was 10.02 %, (95%C.I. 7.88 -12.16), DM patients showed a higher risk of developing PD (OR: 1.34 95%CI 1.26-1.43 p < 0.0001) compared to non-DM, and PD patients with DM showed a greater severity of motor symptoms, with higher Hoehn and Yahr stage (SMD: 0.36 95%CI 0.12-0.60; p < 0.001) and higher UPDRS (SMD 0.60 95%CI 0.28-0.92; p < 0.001) compared with PD patients without DM.

CONCLUSION

Although the prevalence of DM in PD patients is similar to the general population, patients with DM have a higher risk of developing PD, and the presence of DM is associated with greater PD severity and faster progression, which suggests that DM may be a facilitating factor of neurodegeneration.

Dynamic changes of activated AHR in microglia and astrocytes in the substantia nigra-striatum system in an MPTP-induced Parkinson's disease mouse model

Aryl Hydrocarbon Receptor (AHR) is a ligand-activated transcription factor expressed in various brain regions. However, little is known about the role of AHR during neuroinflammation in the 1-methyl-4-phenyl-1,2,3,6-tetrathydropyridine (MPTP)-induced Parkinson's disease (PD) mouse model. Here, mice were sacrificed at day 4, day 6 and day 8 respectively after MPTP or saline treatment. Behavioral tests, Tyrosine hydroxylase (TH) expression, glial reaction, and AHR expression and activation were then assayed. As expected, mice treated with MPTP showed apparent behavioral dysfunctions and significantly reduced TH content. Immunofluorescence (IF) labeling showed an increased trend of phosphorylated AHR activation in the Substantia Nigra pars compacta (SNpc) and striatum after MPTP treatment. Western blot analysis demonstrated that MPTP treatment induced a significantly increased level of AHR at each time point tested, with the highest level observed at day 6 in the striatum. To determine exactly the AHR activation in relation to changes of glial cell reactivity, double IF labeling was performed for either IBA1 (microglia marker) and p-AHR, or GFAP (astrocyte marker) and p-AHR. The results demonstrated that MPTP treatment not only increases the number of p-AHR-positive IBA1-expressing cells in the striatum and the SNpc, but also increases that of p-AHR-positive GFAP-expressing cells in the striatum. Intriguingly, the increase of the number of cells co-expressing both p-AHR and IBA1 was highest at day 4 in response to MPTP in the striatum and at day 8 in the SNpc. The number of cells co-expressing both p-AHR and GFAP was increased at days 4, 6 and 8 in the striatum. In conclusion, our study suggests that AHR activation may facilitate PD diagnosis and serve as a target for the treatment of PD.

Association Between Heart Rate Variability and Parkinson's Disease: A Meta-analysis

AIM

A systematic review which aims to assess the evidence regarding the function of the autonomic heart rate regulation system among Parkinson's disease (PD) patients. The main objective of the study is to compare heart rate variability (HRV) between those with and without PD from published studies. The subgroup analyses aimed to investigate the impact of treatment and disease duration on heart rate variability (HRV), assessed by measuring sympathetic and parasympathetic activity via low-frequency (LF) and high-frequency (HF) power spectrum scores, in patients with Parkinson's disease (PD).

METHODS

PubMed, Cochrane Library, Embase and Web of Science were searched using the keywords "Parkinson's disease" and "heart rate variability". Studies that reported at least one HRV variable were included. The quality of the included studies was evaluated, and the relevant information was extracted. A meta-analysis was carried out with Stata software. We followed the PRISMA guidelines for all stages of the meta-analysis. PROSPERO registration number: CRD42021242766.

RESULTS

Thirteen references (16 studies) were included in our analysis. The LF values (g -0.27; 95% confidence interval (CI) -0.53 to -0.01) of the patients with PD were lower than the controls. No significant differences in HF values (g -0.11; 95% CI -0.28 to 0.06) were observed between groups. Subgroup analyses of HRV outcomes in patients stratified by treatment status and disease duration were performed. For LF, patients with a disease duration of less than 5 years presented lower HF (g -0.25; 95% CI -0.44 to -0.06) values than controls. Regarding HF, patients receiving treatment presented lower HF (g -0.22; 95% CI -0.40 to 0.05) values than controls, and patients with a disease duration greater than 5 years also presented lower HF (g -0.29; 95% CI -0.56 to -0.03) values than controls.

DISCUSSION

We have confirmed and elaborated on the hypothesis of sympathovagal imbalance in PD. Knowledge of the effect of sympathovagal balance on HRV may inform the design of therapeutic regimens for PD. However, between-study heterogeneity and methodological issues limit the generalizability of the evidence; thus, future studies employing strict methodologies are warranted.

CONCLUSION

Our meta-analysis found that PD is associated with reduced HRV values, which indicates that both sympathetic and vagal activities are decreased. Patients in the early stage of PD have sympathetic autonomic nerve dysfunction, with only minor damage to sympathetic activity.

Respiratory Disorders in Parkinson's Disease

BACKGROUND

Parkinson's disease (PD) non motor symptoms may present early in the disease course and worsen with advancing disease. Respiratory changes can affect individuals to remain physically active, contributing to a reduction of functionality and quality of life.

OBJECTIVE

The aim of this systematic review is to synthesize evidence of respiratory disorders in patients with PD.

METHODS

An electronic search was performed up to November 2020 on PubMed-MEDLINE, Embase, Web of Science, Lilacs, Cinahl, and Cochrane using the following keyword combination: [("Parkinson disease") AND ("respiratory function tests" OR "evaluation") AND ("respiratory system" OR "respiration disorders" OR "respiratory muscles")].

RESULTS

The electronic search resulted in 601 references in English or Portuguese. The selection process and data extraction were made by two independent reviewers. We selected 19 studies including cross-sectional studies that investigated the respiratory disorders in patients with PD through pulmonary function, respiratory muscle strength, or physical capacity evaluation. We excluded studies that considered patients with other diseases. Eighteen studies evaluated the pulmonary function in patients with PD, eleven studies verified the influence of PD on respiratory muscle strength, and three studies assessed the physical capacity through functional tests.

CONCLUSION

The evidence showed that PD patients have higher chances to present a pulmonary dysfunction, either obstructive or restrictive, when compared to healthy subjects. In addition, these patients present lower respiratory muscle strength and a consequent decrease in physical capacity in endurance exercises. The respiratory impairment in PD seems to be directly related to the progression of the disease.

The Baseline Structure of the Enteric Nervous System and Its Role in Parkinson's Disease

The gastrointestinal (GI) tract is provided with a peculiar nervous network, known as the enteric nervous system (ENS), which is dedicated to the fine control of digestive functions. This forms a complex network, which includes several types of neurons, as well as glial cells. Despite extensive studies, a comprehensive classification of these neurons is still lacking. The complexity of ENS is magnified by a multiple control of the central nervous system, and bidirectional communication between various central nervous areas and the gut occurs. This lends substance to the complexity of the microbiota–gut–brain axis, which represents the network governing homeostasis through nervous, endocrine, immune, and metabolic pathways. The present manuscript is dedicated to identifying various neuronal cytotypes belonging to ENS in baseline conditions. The second part of the study provides evidence on how these very same neurons are altered during Parkinson’s disease. In fact, although being defined as a movement disorder, Parkinson’s disease features a number of degenerative alterations, which often anticipate motor symptoms. Among these, the GI tract is often involved, and for this reason, it is important to assess its normal and pathological structure. A deeper knowledge of the ENS is expected to improve the understanding of diagnosis and treatment of Parkinson’s disease.

THE ROLE OF CIRCADIAN REGULATION OF GHRELIN LEVELS IN PARKINSON’S DISEASE (LITERATURE REVIEW)

The paper is aimed at the analysis of the role of the circadian regulation of ghrelin levels in patients with Parkinson’s disease. Based on the literature data, patients with Parkinson’s disease have clinical fluctuations in the symptoms of the disease, manifested by the diurnal changes in motor activity, autonomic functions, sleep-wake cycle, visual function, and the efficacy of dopaminergic therapy. Biological rhythms are controlled by central and peripheral oscillators which links with dopaminergic neurotransmission – core of the pathogenesis of Parkinson`s disease. Circadian system is altered in Parkinson`s disease due to that ghrelin fluctuations may be changed. Ghrelin is potential food-entrainable oscillator because it is linked with clock genes expression. In Parkinson`s disease this hormone may induce eating behavior changing and as a result metabolic disorder. The “hunger hormone” ghrelin can be a biomarker of the Parkinson’s disease, and the study of its role in the pathogenesis, as well as its dependence on the period of the day, intake of levodopa medications to improve the effectiveness of treatment is promising.

Predictors of Global Non-Motor Symptoms Burden Progression in Parkinson's Disease. Results from the COPPADIS Cohort at 2-Year Follow-Up

Background and Objective: Non-motor symptoms (NMS) progress in different ways between Parkinson's disease (PD) patients. The aim of the present study was to (1) analyze the change in global NMS burden in a PD cohort after a 2-year follow-up, (2) to compare the changes with a control group, and (3) to identify predictors of global NMS burden progression in the PD group. Material and Methods: PD patients and controls, recruited from 35 centers of Spain from the COPPADIS cohort from January 2016 to November 2017, were followed-up with after 2 years. The Non-Motor Symptoms Scale (NMSS) was administered at baseline (V0) and at 24 months ± 1 month (V2). Linear regression models were used for determining predictive factors of global NMS burden progression (NMSS total score change from V0 to V2 as dependent variable). Results: After the 2-year follow-up, the mean NMS burden (NMSS total score) significantly increased in PD patients by 18.8% (from 45.08 ± 37.62 to 53.55 ± 42.28; p < 0.0001; N = 501; 60.2% males, mean age 62.59 ± 8.91) compared to no change observed in controls (from 14.74 ± 18.72 to 14.65 ± 21.82; p = 0.428; N = 122; 49.5% males, mean age 60.99 ± 8.32) (p < 0.0001). NMSS total score at baseline (β = -0.52), change from V0 to V2 in PDSS (Parkinson's Disease Sleep Scale) (β = -0.34), and change from V0 to V2 in NPI (Neuropsychiatric Inventory) (β = 0.25) provided the highest contributions to the model (adjusted R-squared 0.41; Durbin-Watson test = 1.865). Conclusions: Global NMS burden demonstrates short-term progression in PD patients but not in controls and identifies worsening sleep problems and neuropsychiatric symptoms as significant independent predictors of this NMS progression.

Na+ leak-current channel (NALCN) at the junction of motor and neuropsychiatric symptoms in Parkinson's disease

Parkinson's disease (PD) is a debilitating movement disorder often accompanied by neuropsychiatric symptoms that stem from the loss of dopaminergic function in the basal ganglia and altered neurotransmission more generally. Akinesia, postural instability, tremors and frozen gait constitute the major motor disturbances, whereas neuropsychiatric symptoms include altered circadian rhythms, disordered sleep, depression, psychosis and cognitive impairment. Evidence is emerging that the motor and neuropsychiatric symptoms may share etiologic factors. Calcium/ion channels (CACNA1C, NALCN), synaptic proteins (SYNJ1) and neuronal RNA-binding proteins (RBFOX1) are among the risk genes that are common to PD and various psychiatric disorders. The Na⁺ leak-current channel (NALCN) is the focus of this review because it has been implicated in dystonia, regulation of movement, cognitive impairment, sleep and circadian rhythms. It regulates the resting membrane potential in neurons, mediates pace-making activity, participates in synaptic vesicle recycling and is functionally co-localized to the endoplasmic reticulum (ER)-several of the major processes adversely affected in PD. Here, we summarize the literature on mechanisms and pathways that connect the motor and neuropsychiatric symptoms of PD with a focus on recurring relationships to the NALCN. It is hoped that the various connections outlined here will stimulate further discussion, suggest additional areas for exploration and ultimately inspire novel treatment strategies.

Recent Advances in Chemical Biology of Mitochondria Targeting

Mitochondria are vital subcellular organelles that generate most cellular chemical energy, regulate cell metabolism and maintain cell function. Mitochondrial dysfunction is directly linked to numerous diseases including neurodegenerative disorders, diabetes, thyroid squamous disease, cancer and septicemia. Thus, the design of specific mitochondria-targeting molecules and the realization of real-time acquisition of mitochondrial activity are powerful tools in the study and treatment of mitochondria dysfunction in related diseases. Recent advances in mitochondria-targeting agents have led to several important mitochondria chemical probes that offer the opportunity for selective targeting molecules, novel biological applications and therapeutic strategies. This review details the structural and physiological functional characteristics of mitochondria, and comprehensively summarizes and classifies mitochondria-targeting agents. In addition, their pros and cons and their related chemical biological applications are discussed. Finally, the potential biomedical applications of these agents are briefly prospected.

The association of enteric neuropathy with gut phenotypes in acute and progressive models of Parkinson's disease

Parkinson's disease (PD) is associated with neuronal damage in the brain and gut. This work compares changes in the enteric nervous system (ENS) of commonly used mouse models of PD that exhibit central neuropathy and a gut phenotype. Enteric neuropathy was assessed in five mouse models: peripheral injection of MPTP; intracerebral injection of 6-OHDA; oral rotenone; and mice transgenic for A53T variant human α-synuclein with and without rotenone. Changes in the ENS of the colon were quantified using pan-neuronal marker, Hu, and neuronal nitric oxide synthase (nNOS) and were correlated with GI function. MPTP had no effect on the number of Hu+ neurons but was associated with an increase in Hu+ nuclear translocation (P < 0.04). 6-OHDA lesioned mice had significantly fewer Hu+ neurons/ganglion (P < 0.02) and a reduced proportion of nNOS+ neurons in colon (P < 0.001). A53T mice had significantly fewer Hu+ neurons/area (P < 0.001) and exhibited larger soma size (P < 0.03). Treatment with rotenone reduced the number of Hu+ cells/mm2 in WT mice (P < 0.006) and increased the proportion of Hu+ translocated cells in both WT (P < 0.02) and A53T mice (P < 0.04). All PD models exhibited a degree of enteric neuropathy, the extent and type of damage to the ENS, however, was dependent on the model.

Periphery and brain, innate and adaptive immunity in Parkinson's disease

Parkinson’s disease (PD) is a neurodegenerative disorder where alpha-synuclein plays a central role in the death and dysfunction of neurons, both, in central, as well as in the peripheral nervous system. Besides the neuronal events observed in patients, PD also includes a significant immune component. It is suggested that the PD-associated immune response will have consequences on neuronal health, thus opening immunomodulation as a potential therapeutic strategy in PD. The immune changes during the disease occur in the brain, involving microglia, but also in the periphery with changes in cells of the innate immune system, particularly monocytes, as well as those of adaptive immunity, such as T-cells. This realization arises from multiple patient studies, but also from data in animal models of the disease, providing strong evidence for innate and adaptive immune system crosstalk in the central nervous system and periphery in PD. Here we review the data showing that alpha-synuclein plays a crucial role in the activation of the innate and adaptive immune system. We will also describe the studies suggesting that inflammation in PD includes early changes in innate and adaptive immune cells that develop dynamically through time during disease, contributing to neuronal degeneration and symptomatology in patients. This novel finding has contributed to the definition of PD as a multisystem disease that should be approached in a more integratory manner rather than a brain-focused classical approach.

Therapeutic Applications of Botulinum Neurotoxin for Autonomic Symptoms in Parkinson's Disease: An Updated Review

Parkinson's disease is the most common age-related motoric neurodegenerative disease. In addition to the cardinal motor symptoms of tremor, rigidity, bradykinesia, and postural instability, there are numerous non-motor symptoms as well. Among the non-motor symptoms, autonomic nervous system dysfunction is common. Autonomic symptoms associated with Parkinson's disease include sialorrhea, hyperhidrosis, gastrointestinal dysfunction, and urinary dysfunction. Botulinum neurotoxin has been shown to potentially improve these autonomic symptoms. In this review, the varied uses of botulinum neurotoxin for autonomic dysfunction in Parkinson's disease are discussed. This review also includes discussion of some additional indications for the use of botulinum neurotoxin in Parkinson's disease, including pain.

Could Small Heat Shock Protein HSP27 Be a First-Line Target for Preventing Protein Aggregation in Parkinson's Disease?

Small heat shock proteins (HSPs), such as HSP27, are ubiquitously expressed molecular chaperones and are essential for cellular homeostasis. The major functions of HSP27 include chaperoning misfolded or unfolded polypeptides and protecting cells from toxic stress. Dysregulation of stress proteins is associated with many human diseases including neurodegenerative diseases, such as Parkinson's disease (PD). PD is characterized by the presence of aggregates of α-synuclein in the central and peripheral nervous system, which induces the degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and in the autonomic nervous system. Autonomic dysfunction is an important non-motor phenotype of PD, which includes cardiovascular dysregulation, among others. Nowadays, the therapies for PD focus on dopamine (DA) replacement. However, certain non-motor symptoms with a great impact on quality of life do not respond to dopaminergic drugs; therefore, the development and testing of new treatments for non-motor symptoms of PD remain a priority. Since small HSP27 was shown to prevent α-synuclein aggregation and cytotoxicity, this protein might constitute a suitable target to prevent or delay the motor and non-motor symptoms of PD. In the first part of our review, we focus on the cardiovascular dysregulation observed in PD patients. In the second part, we present data on the possible role of HSP27 in preventing the accumulation of amyloid fibrils and aggregated forms of α-synuclein. We also include our own studies, highlighting the possible protective cardiac effects induced by L-DOPA treatment through the enhancement of HSP27 levels and activity.

Human moral decision-making through the lens of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the basal ganglia (BG) and thalamocortical circuitry. While defective motor control has long been considered the defining symptom of PD, mounting evidence indicates that the BG are fundamentally important for a multitude of cognitive, emotional, and motivational processes in addition to motor function. Here, we review alterations in moral decision-making in people with PD, specifically in the context of deceptive behavior. We report that PD patients exhibit two opposite behavioral patterns: hyper- and hypo-honesty. The hyper-honest subgroup engages in deception less often than matched controls, even when lying is associated with a monetary payoff. This behavioral pattern seems to be linked to dopaminergic hypo-activity, implying enhanced harm avoidance, risk aversion, non-impulsivity, and reduced reward sensitivity. On the contrary, the hypo-honest subgroup-often characterized by the additional diagnosis of impulse control disorders (ICDs) and dopamine dysregulation syndrome (DDS)-deceives more often than both PD patients without ICDs/DDS and controls. This behavioral pattern appears to be associated with dopaminergic hyperactivity, which underpins enhanced novelty-seeking, risk-proneness, impulsivity, and reward sensitivity. We posit that these two complementary behavioral patterns might be related to dysfunction of the dopaminergic reward system, leading to reduced or enhanced motivation to deceive. Only a few studies have directly investigated moral decision-making in PD and other neurodegenerative disorders affecting the BG, and further research on the causal role of subcortical structures in shaping moral behavior is needed.

Non-motor complications in late stage Parkinson's disease: recognition, management and unmet needs

Introduction: The burden of non-motor symptoms (NMS) is a major determinant of health-related quality of life in Parkinson's disease (PD), particularly at its late stage.Areas covered: The late stage is usually defined as the period from unstable advanced to the palliative stage, characterized by a combination of emerging treatment-resistant axial motor symptoms (freezing of gait, postural instability, falls and dysphagia), as well as both non-dopaminergic and dopaminergic NMS: cognitive decline, neuropsychiatric symptoms, aspects of dysautonomia, pain and sleep disturbances (insomnia and excessive day-time sleepiness). Here, the authors summarize the current knowledge on NMS dominating the late stage of PD and propose a pragmatic and clinically focused approach for their recognition and treatment.Expert opinion: The NMS progression pattern is complex and remains under-researched. While dopamine-dependent NMS may improve with dopamine replacement therapy, non-dopamine dependent NMS worsen progressively and culminate at the late stages of PD. Furthermore, some PD specific features could interact negatively with other comorbidities, multiple medication use and frailty - the evaluation of these aspects is important in the creation of personalized management plans in the late stage of PD.

Heart Matters: Cardiac Dysfunction and Other Autonomic Changes in Parkinson's Disease

It has been more than 200 years since James Parkinson made the first descriptions of the disease that bears his name. Since then, knowledge about Parkinson's disease has been improved, and its pathophysiology, diagnosis, and treatments are well described in the scientific and medical literature. However, there is no way to prevent the disease from its progressive nature yet and only its symptoms can be minimized. It is known that the process of neurodegeneration begins before the onset of motor signs and symptoms of the disease, when diagnosis is usually made. Therefore, recognizing manifested non-motor symptoms can make an early diagnosis possible and lead to a better understanding of the disease. Autonomic dysfunctions are important non-motor manifestations of Parkinson's disease and affect the majority of patients. Importantly, heart failure is the third leading cause of death in people suffering from Parkinson's disease. Several evidences have shown the correlation between Parkinson's disease and the preexistence of cardiovascular diseases. Therefore, cardiovascular monitoring and identification of its dysfunctions can have a prodromal role for Parkinson's disease. This review presents studies of the literature that can lead to a better understanding of Parkinson's disease with special attention to its relation to heart and cardiovascular parameters.

The Association Between REM Sleep Behavior Disorder and Autonomic Dysfunction in Parkinson's Disease

BACKGROUND

REM behavior disorder (RBD) can occur in the context of neurodegenerative alpha-synucleinopathies, such as Parkinson's disease (PD). PD patients with RBD (PD-pRBD) represent more severe symptoms and signs compared with those without RBD (PD-nRBD). On another note, autonomic dysfunction in PD patients is categorized as one of the most prominent non-motor symptoms and has been lately the field of interest in research.

OBJECTIVE

In the current study, we longitudinally studied autonomic dysfunction in PD-pRBD and PD-nRBD groups.

METHOD

This study was conducted on 420 drug-naïve PD patients selected from the Parkinson's Progression Markers Initiative database. The RBD Screening Questionnaire was used to define the presence of probable RBD. SCOPA-AUT was used to assess autonomic dysfunction. Additionally, dopamine transporter deficits on [123I] FP-CIT SPECT imaging was performed for all of the patients.

RESULTS

Out of 420 PD patients, 158 individuals (37.6%) were considered to have probable RBD (PD-pRBD) and others without RBD (PD-nRBD). Except for pupillomotor function, all the autonomic symptoms were significantly more severe in PD-pRBD group. In PD-nRBD group, caudate striatal binding ratio was negatively correlated with SCOPA-AUT scores, while no significant correlation was observed in PD-pRBD group. Finally, there was a significant difference considering the longitudinal changes of SCOPA-AUT total between PD-pRBD and PD-nRBD groups, suggesting a more severe autonomic decline in PD-pRBD patients.

CONCLUSION

Our results indicate that PD-pRBD patients have more severe autonomic dysfunction. These results support the theory that PD patients can be categorized based on the clinical presentation, possibly representing differences in the disease pathophysiology.

Parkinson-like early autonomic dysfunction induced by vagal application of DOPAL in rats

AIM

To understand why autonomic failures, a common non-motor symptom of Parkinson's disease (PD), occur earlier than typical motor disorders.

METHODS

Vagal application of DOPAL (3,4-dihydroxyphenylacetaldehyde) to simulate PD-like autonomic dysfunction and understand the connection between PD and cardiovascular dysfunction. Molecular and morphological approaches were employed to test the time-dependent alternation of α-synuclein aggregation and the ultrastructure changes in the heart and nodose (NG)/nucleus tractus solitarius (NTS).

RESULTS

Blood pressure (BP) and baroreflex sensitivity of DOPAL-treated rats were significantly reduced accompanied with a time-dependent change in orthostatic BP, consistent with altered echocardiography and cardiomyocyte mitochondrial ultrastructure. Notably, time-dependent and collaborated changes in Mon-/Tri-α-synuclein were paralleled with morphological alternation in the NG and NTS.

CONCLUSION

These all demonstrate that early autonomic dysfunction mediated by vagal application of DOPAL highly suggests the plausible etiology of PD initiated from peripheral, rather than central site. It will provide a scientific basis for the prevention and early diagnosis of PD.

QTc Interval Prolongation with Therapies Used to Treat Patients with Parkinson's Disease Psychosis: A Narrative Review

In addition to the classic motor symptoms of Parkinson's disease (PD), people with PD frequently experience nonmotor symptoms that can include autonomic dysfunction and neuropsychiatric symptoms such as PD psychosis (PDP). Common patient characteristics, including older age, use of multiple medications, and arrhythmias, are associated with increased risk of corrected QT interval (QTc) prolongation, and treatments for PDP (antipsychotics, dementia medications) may further increase this risk. This review evaluates how medications used to treat PDP affect QTc interval from literature indexed in the PubMed and Embase databases. Although not indicated for the treatment of psychosis, dementia therapies such as donepezil, rivastigmine, memantine, and galantamine are often used with or without antipsychotics and have minimal effects on QTc interval. Among the antipsychotics, data suggesting clinically meaningful QTc interval prolongation are limited. However, many antipsychotics have other safety concerns. Aripiprazole, olanzapine, and risperidone negatively affect motor function and are not recommended for PDP. Quetiapine is often sedating, can exacerbate underlying neurogenic orthostatic hypotension, and may prolong the QTc interval. Pimavanserin was approved by the US Food and Drug Administration (FDA) in 2016 and remains the only FDA-approved medication available to treat hallucinations and delusions associated with PDP. However, pimavanserin can increase QTc interval by approximately 5-8 ms. The potential for QTc prolongation should be considered in patients with symptomatic cardiac arrhythmias and those receiving QT-prolonging medications. In choosing a medication to treat PDP, expected efficacy must be balanced with potential safety concerns for individual patients.

SARS-CoV-2 infection in patients with serious mental illness and possible benefits of prophylaxis with Memantine and Amantadine

Patients with serious mental illness are a high-risk category of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Patients with schizophrenia are not participatory and have increased mortality and morbidity, patients with dementia cannot be cared for while depression, anxiety, bipolar tubing are associated with low immune status. Social stress is amplified by social isolation, amplifying depression and the mechanisms of decreased immunity. Hygiene measures and prophylactic behavior are impossible to put into practice in conditions of chronic mental illness. In coronavirus disease 2019 (COVID-19), the risk for severe development is associated with the presence of comorbidities and immune system deficiency. Prothrombotic status, cytokine storm and alveolar destruction are mechanisms that aggravate the evolution of patients, especially in the context in which they have dysfunction of the autonomic system. The activity of proinflammatory cytokines is accentuated by hyperglutamatergia, which potentiates oxidative stress and triggers the mechanisms of neural apoptosis by stimulating microglial activation. Activation of M1-type microglia has an important role in pathogenesis of major psychiatric disorders, such as major depression, schizophrenia or bipolar disorder, and may associate hippocampal atrophy and disconnection of cognitive structures. Memantine and Amantadine, N-methyl-D-aspartate (NMDA) glutamate receptor inhibitors, have demonstrated, through their pharmacological profile, psychotropic effects but also antiviral properties. In the conditions of the COVID-19 pandemic, based on these arguments, we suggest that they can be associated with the therapy with the basic psychotropics, Memantine or Amantadine, for the control of neuropsychiatric symptoms but also as adjuvants with antiviral action.

The diversity of neuronal phenotypes in rodent and human autonomic ganglia

Selective sympathetic and parasympathetic pathways that act on target organs represent the terminal actors in the neurobiology of homeostasis and often become compromised during a range of neurodegenerative and traumatic disorders. Here, we delineate several neurotransmitter and neuromodulator phenotypes found in diverse parasympathetic and sympathetic ganglia in humans and rodent species. The comparative approach reveals evolutionarily conserved and non-conserved phenotypic marker constellations. A developmental analysis examining the acquisition of selected neurotransmitter properties has provided a detailed, but still incomplete, understanding of the origins of a set of noradrenergic and cholinergic sympathetic neuron populations, found in the cervical and trunk region. A corresponding analysis examining cholinergic and nitrergic parasympathetic neurons in the head, and a range of pelvic neuron populations, with noradrenergic, cholinergic, nitrergic, and mixed transmitter phenotypes, remains open. Of particular interest are the molecular mechanisms and nuclear processes that are responsible for the correlated expression of the various genes required to achieve the noradrenergic phenotype, the segregation of cholinergic locus gene expression, and the regulation of genes that are necessary to generate a nitrergic phenotype. Unraveling the neuron population-specific expression of adhesion molecules, which are involved in axonal outgrowth, pathway selection, and synaptic organization, will advance the study of target-selective autonomic pathway generation.

Isoproterenol-Dependent Activation of TRPM7 Protects Against Neurotoxin-Induced Loss of Neuroblastoma Cells

Neuronal function and their survival depend on the activation of ion channels. Loss of ion channel function is known to induce neurodegenerative diseases such as Parkinson’s that exhibit loss of dopaminergic neurons; however, mechanisms that could limit neuronal loss are not yet fully identified. Our data suggest that neurotoxin-mediated loss of neuroblastoma SH-SY5Y cells is inhibited by the addition of β-adrenergic receptor (β-AR) agonist isoproterenol. The addition of isoproterenol to SHSY-5Y cells showed increased Mg²⁺ influx and cell survival in the presence of neurotoxin especially at higher concentration of isoproterenol. Importantly, isoproterenol potentiated transient receptor potential melastatin-7 (TRPM7) channel activation that leads to an increase in intracellular Mg²⁺ levels. The addition of 2APB, which is a known TRPM7 channel blocker, significantly decreased the TRPM7 function and inhibited isoproterenol-mediated protection against neurotoxins. Moreover, neurotoxins inhibited TRPM7 expression and function, but the restoration of TRPM7 expression increased neuroblastoma cell survival. In contrast, TRPM7 silencing increased cell loss, decreased Mg²⁺ homeostasis, and inhibited mitochondrial function. Moreover, isoproterenol treatment prevented neurotoxin-mediated loss of TRPM7 expression and inhibited Bax expression that induces cell survival. These effects were dependent on the neurotoxin-induced increase in oxidative stress, which inhibits TRPM7 expression and function. Together, our results suggest a positive role for β-AR in activating TRPM7 channels that regulate Mg²⁺ homeostasis and are essential for the survival of SH-SY5Y cells from neurotoxin.