Gastrointestinal dysfunction in Parkinson's disease

The Influence of Small Intestinal Bacterial Overgrowth in Digestive and Extra-Intestinal Disorders

Small intestinal bacterial overgrowth (SIBO) is a condition hallmarked by an increase in the concentration of colonic-type bacteria in the small bowel. Watery diarrhea, bloating, abdominal pain and distension are the most common clinical manifestations. Additionally, malnutrition and vitamin (B12, D, A, and E) as well as minerals (iron and calcium) deficiency may be present. SIBO may mask or worsen the history of some diseases (celiac disease, irritable bowel disease), may be more common in some extra-intestinal disorders (scleroderma, obesity), or could even represent a pathogenetic link with some diseases, in which a perturbation of intestinal microbiota may be involved. On these bases, we performed a review to explore the multiple links between SIBO and digestive and extra-intestinal diseases.

The impact of risk factors on gastroparesis at an urban medical center

Background

Gastroparesis is a complex and poorly understood disease. The literature is lacking with respect to the epidemiology of patient comorbidities and their effect on gastric emptying. We aimed to describe the most common comorbid conditions among patients with gastroparesis in an urban population and quantify the effect of these comorbidities on the severity of delayed gastric emptying (DGE).

Methods

We examined the medical records of all patients diagnosed with gastroparesis at a quaternary care center between 2014 and 2015. The severity of DGE was analyzed after patients were stratified for possible causative etiologies. Likelihood ratio tests were used to assess the significance of demographic and scintigraphic variation in this population.

Results

Of the 221 patients, 56.1% were Caucasian and 31.7% were African American. Among these patients, 29.4% had evidence of medication-associated gastroparesis, 29.0% had diabetes-associated gastroparesis, and 31.7% had idiopathic disease. African American patients with gastroparesis were more likely to have diabetic gastroparesis than patients of other races (P=0.01). There was a statistically significant relationship between the number of major risk factors and the severity of a patient's DGE (P=0.004).

Conclusions

Among a diverse urban population, patients with DGE often carry multiple comorbid conditions that serve as risk factors for the development of gastroparesis, including prescriptions for narcotic medications. Greater numbers of these comorbid conditions are associated with more severe disease. Demographics are significantly associated with the etiology and severity of gastroparesis; in particular, African American patients are more likely to have diabetic gastroparesis than patients of other races.

Changes in the expression of oxidative phosphorylation complexes in the aging intestinal mucosa

OBJECTIVE

Mitochondria produce cellular energy via oxidative phosphorylation (OXPHOS), mediated by respiratory chain complexes I to IV and ATP synthase (complex V). Mitochondrial respiratory complexes have been shown to decline with age in several tissues. As the intestinal epithelium is a tissue with a high energy demand, the aim of the present study was to establish whether the expression profile of OXPHOS subunits in the intestinal mucosa changes during the aging process.

DESIGN

Biopsies of intestinal mucosa with no evidence of endoscopic or histomorphologic abnormalities, taken from 55 patients (mean age 42 years, age range 4-82 years; 62% female), were divided into four age groups (4-19, 20-39, 40-59, ≥60 years). Sections from different intestinal segments (terminal ileum, ascending colon, and sigmoid colon/rectum) were stained immunohistochemically (IHC) for subunits of OXPHOS complexes I-V and the voltage-dependent anion-selective channel 1 protein (VDAC1, porin), a marker of mitochondrial mass. Scores for IHC staining were determined by multiplication of the staining intensity and the percentage of positive cells. In addition, the numbers of intestinal crypts staining positive, partly positive, and negative were assessed.

RESULTS

The average protein expression levels of OXPHOS subunits increased continuously from childhood onward, peaked in persons aged 20 to 59 years, and declined thereafter. This was seen for complexes II to V in the terminal ileum, complexes I to V in the ascending colon, and complexes I to IV in the sigmoid colon/rectum. Across all age groups, no effect of age on expression of the porin subunit VDAC1 was detected. The number of complex I- and IV-negative crypts in different intestinal segments increased with age.

CONCLUSION

The protein expression levels of OXPHOS complexes increases from childhood onward and declines in elderly individuals, while the numbers of crypts with partial or complete loss of expression of complexes I and IV increase continuously with age. These data suggest that the continued reductions in the levels of mitochondrial OXPHOS complexes in crypts might be compensated in adulthood, but that, ultimately, reduced expression levels occur in persons aged 60 years and older. These findings raise two important questions: first, can the process of aging could be delayed through (pharmacological) intervention of mitochondrial pathways, and second, pathophysiologically, are these findings associated with disorders of the intestinal mucosa, e.g. inflammation?

Effect of Intestinal Levodopa-Carbidopa Infusion on Pharyngeal Dysphagia: Results from a Retrospective Pilot Study in Patients with Parkinson's Disease

Background

Pharyngeal dysphagia is a common symptom of Parkinson's disease (PD) leading to severe complications. PD-related pharyngeal dysphagia (PDrPD) may significantly improve in up to half of patients following acute oral levodopa challenge.

Objective

The aim of this study was to investigate the effects of levodopa-carbidopa intestinal gel (LCIG) on PDrPD.

Methods

Forty-five PD patients under LCIG treatment were available for retrospective analysis. In all patients with PDrPD who underwent flexible endoscopic evaluation of swallowing (FEES) in the clinical “on-state” both before and after implementation of LCIG treatment, FEES videos were systematically reassessed. PDrPD was characterized using a PD-specific FEES score evaluating premature bolus spillage, penetration/aspiration, and pharyngeal residue. Further, the duration of white-out was assessed, as a parameter for pharyngeal bradykinesia.

Results

Eleven patients with PDrPD (mean age 74.6 ± 4.4 years; mean Hoehn and Yahr stage 3.8 ± 0.6) received FEES both before and after the onset of LCIG treatment. The mean swallowing score improved from 14.9 ± 7.3 to 13.0 ± 6.9 after implementation of LCIG; however, this difference was not significant (p=0.312). Premature bolus spillage decreased significantly (p=0.002) from 5.4 ± 1.1 to 3.6 ± 1.0, and white-out duration decreased significantly (p=0.002) from 984 ± 228 ms to 699 ± 131 ms after implementation of LCIG.

Conclusions

LCIG may affect PDrPD and reduce premature bolus spillage and pharyngeal bradykinesia. Future studies with larger sample sizes are required to follow-up on these pilot results and identify which factors predict a good response of PDrPD to LCIG treatment.

The gut microbiome in Parkinson's disease: A culprit or a bystander?

In recent years, large-scale metagenomics projects such as the Human Microbiome Project placed the gut microbiota under the spotlight of research on its role in health and in the pathogenesis several diseases, as it can be a target for novel therapeutical approaches. The emerging concept of a microbiota modulation of the gut-brain axis in the pathogenesis of neurodegenerative disorders has been explored in several studies in animal models, as well as in human subjects. Particularly, research on changes in the composition of gut microbiota as a potential trigger for alpha-synuclein (α-syn) pathology in Parkinson's disease (PD) has gained increasing interest. In the present review, we first provide the basis to the understanding of the role of gut microbiota in healthy subjects and the molecular basis of the gut-brain interaction, focusing on metabolic and neuroinflammatory factors that could trigger the alpha-synuclein conformational changes and aggregation. Then, we critically explored preclinical and clinical studies reporting on the changes in gut microbiota in PD, as compared to healthy subjects. Furthermore, we examined the relationship between the gut microbiota and PD clinical features, discussing data consistently reported across studies, as well as the potential sources of inconsistencies. As a further step toward understanding the effects of gut microbiota on PD, we discussed the relationship between dysbiosis and response to dopamine replacement therapy, focusing on Levodopa metabolism. We conclude that further studies are needed to determine whether the gut microbiota changes observed so far in PD patients is the cause or, instead, it is merely a consequence of lifestyle changes associated with the disease. Regardless, studies so far strongly suggest that changes in microbiota appears to be impactful in pathogenesis of neuroinflammation. Thus, dysbiotic microbiota in PD could influence the disease course and response to medication, especially Levodopa. Future research will assess the impact of microbiota-directed therapeutic intervention in PD patients.

Pseudovolvulus of the sigmoid colon after percutaneous endoscopic gastrostomy tube placement: A case report

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Percutaneous endoscopic gastrostomy (EPG) is a safe procedure, but complications may occur.

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Major complications of PEG may present with volvulus-like conditions.

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The need for percutaneous endoscopic gastrostomy should be carefully evaluated.

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Laparoscopic gastrostomy and laparoscopic-assisted PEG have been proposed.

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Risk of complications should be timely recognized to enable proper treatment.

Introduction

Percutaneous endoscopic gastrostomy (PEG) provides long-term enteral nutritional access for patients with inability to eat. Although considered safe, PEG tube placement is associated with complications. We report a rare case of PEG-related sigmoid colon pseudovolvulus.

Presentation of case

A 78-year-old man with a history of Parkinson’s disease developed severe abdominal pain and vomited continuously 50 days after PEG tube placement. Contrast-enhanced computed tomography revealed internal herniation of the sigmoid colon between the abdominal wall and the stomach at the gastrostomy site. Intraoperatively, the gastrostomy tube penetrated the sigmoid mesentery, which rotated around the tube, and the sigmoid colon was herniated towards the upper abdomen. The herniated colon was reduced and Hartmann’s procedure was performed. Subsequently, gastrostomy was reinforced with anterior gastropexy. The postoperative course was uneventful.

Discussion

This case highlights the need for caution when placing a PEG tube because of a mobile sigmoid mesocolon, raising the awareness of potential major complications. Complications can be avoided by directly visualising the intraabdominal organs using laparoscopic gastrostomy or laparoscopic-assisted PEG. However, these methods require general anaesthesia. Thus, the presence of redundant colons should be determined in advance to assess the risk of sigmoid mesocolon perforation. We should also assess the patients’ swallowing function and estimate whether it may recover with rehabilitation before deciding to place a PEG tube.

Conclusion

PEG tube should be considered after careful patient evaluation. If PEG is required, clinicians should recognise the patient-specific risks and consider other surgical procedures to avoid complications.

Managing autonomic dysfunction in Parkinson's disease: a review of emerging drugs

Introduction: Autonomic dysfunction is an integral part of Parkinson disease (PD) complex and can be seen both in early and advanced stages. There is a paucity of medicines available to manage autonomic dysfunction in PD and this adds to the considerable morbidity associated with the illness.Areas covered: The pathophysiology and the available therapeutic options of autonomic dysfunction seen in PD are discussed in detail. The potential targets for novel regimens are reviewed and the available literature on the drugs emerging in management of autonomic dysfunction in PD is highlighted.Expert opinion: In the current scenario, there are several drugs that can be tried for constipation viz stool laxatives, prucalopride, prokinetic agents and a high fiber diet. Bladder dysfunction has been treated with β-agonists and with mirabegron, a selective β-3 agonist, the anticholinergic side effects are minimized, and the drug has been found to be effective. Orthostatic hypotension is managed with midodrine while droxidopa is a new drug with promising efficacy. Botulinum toxin works best for management of sialorrhea, but repeated injections are needed.

The role of tissue biopsy as a biomarker in REM sleep behavior disorder

Patients with idiopathic REM-sleep behavior disorder (iRBD) are at substantial risk of progressive neurodegenerative disease of α-synuclein pathology. Longitudinal studies have demonstrated that abnormal α-synuclein deposition occurs early in the course of disease and may precede the appearance of motor symptoms by several decades. This provides rationale for the use of a reliable biomarker to both follow disease progression and to assess treatment response, once disease-modifying treatments become available. Tissue α-synuclein has emerged as a promising candidate, however the utility of α-synuclein detection in tissues accessible to biopsy in iRBD remains unclear. This article summarizes the current literature on the role of tissue biopsy in iRBD, with specific focus on its potential role as a biomarker of disease progression and its role in future clinical trials.

From OFF to ON—Treating OFF Episodes in Parkinson’s Disease

In Parkinson’s disease (PD), OFF episodes continue to present a serious burden for patients, and their effective management remains a substantial unmet clinical need. Understanding of the pathophysiology of OFF episodes has advanced in recent years, providing valuable insights for improved treatments. OFF episodes generally appear 3–5 years after starting levodopa treatment, but can begin much earlier. They are characterized by motor symptoms (including tremor, rigidity, slowness, incoordination, and weakness) and are almost always associated with some non-motor symptoms (including psychological symptoms, pain, urinary problems, swallowing difficulties, and shortness of breath). In PD, higher doses of levodopa are associated with increased risk of motor and non-motor complications, which are notable limitations for longterm therapy. Their occurrence is associated with intermittent levodopa delivery and consequent fluctuating plasma levels. These issues can be offset using lower levodopa doses where possible, incremental dose increases, and combinations of levodopa with other pharmacological agents. OFF episodes in PD can be caused by gastroparesis and/or by Helicobacter pylori infection, which delays delivery of levodopa. These issues can be addressed using new formulations for continuous intrajejunal administration. In addition, pen injector, intranasal, and inhaled dosing systems have been studied and may provide relief via non-intestinal routes. Other approaches include deep-brain stimulation, which is effective but is restricted by costs and potential adverse events. This report presents the highlights of a satellite symposium held at the 14th International Conference on Alzheimer’s & Parkinson’s Diseases (AD/PD™ 2019), Lisbon, Portugal, which discussed the nature of OFF episodes in PD, associated risk factors and the potential of current and future treatments to effectively manage them and increase ON time.

Diet in Parkinson's Disease: Critical Role for the Microbiome

Background: Parkinson's disease (PD) is the most common movement disorder affecting up to 1% of the population above the age of 60 and 4–5% of those above the age of 85. Little progress has been made on efforts to prevent disease development or halt disease progression. Diet has emerged as a potential factor that may prevent the development or slow the progression of PD. In this review, we discuss evidence for a role for the intestinal microbiome in PD and how diet-associated changes in the microbiome may be a viable approach to prevent or modify disease progression.

Methods: We reviewed studies demonstrating that dietary components/foods were related to risk for PD. We reviewed evidence for the dysregulated intestinal microbiome in PD patients including abnormal shifts in the intestinal microbiota composition (i.e., dysbiosis) characterized by a loss of short chain fatty acid (SCFA) bacteria and increased lipopolysaccharide (LPS) bacteria. We also examined several candidate mechanisms by which the microbiota can influence PD including the NLRP3 inflammasome, insulin resistance, mitochondrial function, vagal nerve signaling.

Results: The PD-associated microbiome is associated with decreased production of SCFA and increased LPS and it is believed that these changes may contribute to the development or exacerbation of PD. Diet robustly impacts the intestinal microbiome and the Western diet is associated with increased risk for PD whereas the Mediterranean diet (including high intake of dietary fiber) decreases PD risk. Mechanistically this may be the consequence of changes in the relative abundance of SCFA-producing or LPS-containing bacteria in the intestinal microbiome with effects on intestinal barrier function, endotoxemia (i.e., systemic LPS), NLRP3 inflammasome activation, insulin resistance, and mitochondrial dysfunction, and the production of factors such as glucagon like peptide 1 (GLP-1) and brain derived neurotrophic factor (BDNF) as well as intestinal gluconeogenesis.

Conclusions: This review summarizes a model of microbiota-gut-brain-axis regulation of neuroinflammation in PD including several new mechanisms. We conclude with the need for clinical trials in PD patients to test this model for beneficial effects of Mediterranean based high fiber diets.

Impairment of Nrf2- and Nitrergic-Mediated Gastrointestinal Motility in an MPTP Mouse Model of Parkinson's Disease

BACKGROUND

Gastrointestinal (GI) motility dysfunction is the most common non-motor symptom of Parkinson's disease (PD). Studies have indicated that GI motility functions are impaired before the onset of PD.

AIMS

To investigate the underlying mechanism of PD-induced GI dysmotility in MPTP (1-methyl 4-phenyl 1,2,3,6-tetrahydropyridine)-induced animal model.

METHODS

C57BL/6 mice were administered with or without a selective dopamine neurotoxin, MPTP, to induce parkinsonian symptoms. In addition to in vivo studies, in vitro experiments were also conducted in colon specimens using l-methyl-4-phenylpyridinium (MPP+), a metabolic product of MPTP. Gastric emptying, colon motility, nitrergic relaxation, and western blot experiments were performed as reported.

RESULTS

MPTP-induced PD mice showed decreased expression of nuclear factor erythroid 2-related factor (Nrf2) and its target phase II genes in gastric and colon neuromuscular tissues. Decreased levels of tetrahydrobiopterin (BH4, a critical cofactor for nNOS dimerization) associated with uncoupling of nNOS in gastric and colon tissues exposed to MPTP. Impaired enteric nitrergic system led to delayed gastric emptying and slower colonic motility compared to the control mice. In vitro results in colon specimens confirm that activation of Nrf2 restored MPP+-induced suppression of alpha-synuclein, tyrosine hydroxylase (TH), Nrf2, and heme oxygenase-1. In vitro exposure to L-NAME [N(w)-nitro-L-arginine methyl ester], a NOS synthase inhibitor, reduced protein expression of TH in colon tissue homogenates.

CONCLUSIONS

Loss of Nrf2/BH4/nNOS expression in PD impairs antioxidant gene expression, which deregulates NO synthesis, thereby contributing to the development of GI dysmotility and constipation. Nitric oxide appears to be important to maintain dopamine synthesis in the colon.

Effect of Parkinson's disease and related medications on the composition of the fecal bacterial microbiota

Parkinson's disease (PD) is one of the most common neurodegenerative disorders. PD patients suffer from gastrointestinal dysfunctions and alterations of the autonomous nervous system, especially its part in the gut wall, i.e., the enteric nervous system (ENS). Such alterations and functional gastrointestinal deficits often occur years before the classical clinical symptoms of PD appear. Until now, only little is known about PD-associated changes in gut microbiota composition and their potential implication in PD development. In order to increase knowledge in this field, fecal samples of 34 PD patients and 25 healthy, age-matched control persons were investigated. Here, the V4 and V5 hypervariable region of bacterial 16S rRNA genes was PCR-amplified and sequenced using an Ion Torrent PGM platform. Within the PD group, we observed a relative decrease in bacterial taxa which are linked to health-promoting, anti-inflammatory, neuroprotective or other beneficial effects on the epithelial barrier, such as Faecalibacterium and Fusicatenibacter. Both taxa were lowered in PD patients with elevated levels of the fecal inflammation marker calprotectin. In addition, we observed an increase in shares of the Clostridiales family XI and their affiliated members in these samples. Finally, we found that the relative abundances of the bacterial genera Peptoniphilus, Finegoldia, Faecalibacterium Fusicatenibacter, Anaerococcus, Bifidobacterium, Enterococcus, and Ruminococcus were significantly influenced by medication with L-dopa and entacapone, respectively. Our data confirm previously reported effects of COMT inhibitors on the fecal microbiota of PD patients and suggest a possible effect of L-dopa medication on the relative abundance of several bacterial genera.

Efficacy of electroacupuncture for the treatment of constipation in Parkinson's disease: study protocol for a multicentre randomised controlled trial

INTRODUCTION

Constipation is one of the most common non-motor symptoms in Parkinson's disease (PD). Acupuncture can have a positive on chronic functional constipation and PD, but its efficacy for the treatment of constipation in PD has not yet been confirmed by high-quality clinical trials. Therefore, this study aims to evaluate the efficacy and safety of electroacupuncture (EA) in the treatment of constipation in PD.

METHODS AND ANALYSIS

This study is a multicentre randomised controlled trial. A total of 124 qualified patients with PD and constipation will be randomly divided into the intervention group (62 participants will receive 12 weeks of EA +usual care) or the waitlist control group (62 participants will receive 12 weeks of usual care). EA will be performed three times per week from weeks 1-8, two times per week during weeks 9 and 10, and once a week during weeks 11 and 12. The primary outcome is the change in mean weekly spontaneous bowel movements from baseline to weeks 8 and 9. The secondary outcomes are the changes from baseline in mean weekly bowel movements, mean weekly stool consistency, and mean weekly straining. Other secondary outcomes include the weekly doses of defecation drugs, Visual Analogue Scale for subjective improvements in stool symptoms, Unified Parkinson's Disease Rating Scale, and the time and number of steps required to walk 20 m. Outcomes will be assessed at baseline, week 4, 8, 12 (intervention period); as well as at week 16, 24 (follow-up period).

ETHICS AND DISSEMINATION

Ethical approval has been obtained from four local ethics committees. The results of the study will be published in peer-reviewed journals and will be disseminated through national and international conferences.

TRIAL REGISTRATION NUMBER

ChiCTR1900021053.

α-Synuclein Regulates Development and Function of Cholinergic Enteric Neurons in the Mouse Colon

Alpha-Synuclein (α-Syn) is expressed in the central nervous system and the nervous system of the gut (enteric nervous system, ENS), and is well known to be the major constituent of Lewy bodies which are the hallmark of Parkinson's disease. Gastrointestinal disorders frequently manifest several years before motor deficits develop in Parkinson's patients. Despite extensive research on pathological rodent models, the physiological role of α-Syn in the normal ENS is unclear hampering analysis of its neuropathology. We compared the ENS in colons of α-Syn-knockout (α-Syn KO) and wild-type mice using immunohistochemistry and calcium-imaging of responses to synaptic input. We found that α-Syn is predominantly expressed in cholinergic varicosities, which contain vesicular acetylcholine transporter. α-Syn KO mice had higher enteric neuron density and a larger proportion of cholinergic neurons, notably those containing calretinin, demonstrating a role for α-Syn in regulating development of these neurons. Moreover, α-Syn deletion enhanced the amplitude of synaptically activated [Ca²⁺]_i transients that are primarily mediated by acetylcholine activating nicotinic receptors suggesting that α-Syn modulates the availability of acetylcholine in enteric nerve terminals.

Gastrointestinal Care of the Parkinson Patient

This article reviews the most common gastrointestinal (GI) problems that occur in patients with Parkinson disease, including weight loss, drooling, dysphagia, delayed gastric emptying, constipation, and defecatory dysfunction. Appropriate workup and treatment options are reviewed in detail in order to provide clinicians with a comprehensive and practical guide to managing these problems in Parkinson disease patients. GI adverse effects of commonly used Parkinson disease motor medications are also reviewed.

Constipation in Tg2576 mice model for Alzheimer's disease associated with dysregulation of mechanism involving the mAChR signaling pathway and ER stress response

BACKGROUND

Although constipation has been researched in various neurological disorders, including Parkinson's disease (PD) and spinal cord injury (SCI), the pathological mechanism of this symptom has not been investigated in Alzheimer's disease (AD) associated with loss of nerve cells in the brain. This study was undertaken to gain scientific evidences for a molecular correlation between constipation and AD.

METHODS

To understand the etiology, we measured alterations in various constipation parameters, muscarinic acetylcholine receptors (mAChRs) and endoplasmic reticulum (ER) stress response, in 11-month-old Tg2576 transgenic (Tg) mice showing AD-like phenotypes.

RESULTS

A high accumulation of amyloid beta (Aβ) peptides, a key marker of AD pathology, were detected in the cortex and hippocampus of Tg mice. Furthermore, significant alterations were observed in various constipation parameters including stool weight, histological structure, cytological structure and mucin secretion in Tg2576 mice. Moreover, M2 and M3 expression and the downstream signaling pathways of mAChRs were decreased in the Tg group, as compared with non-Tg (NT) group. Furthermore, activation of ER stress proteins and alteration of ER structure were also detected in the same group.

CONCLUSIONS

The results of the present study provide strong novel evidence that the neuropathological constipation detected in Tg2576 mice is linked to dysregulation of the mAChR signaling pathways and ER stress response.

Epidemiology and Pathophysiology of Gastroparesis

Gastroparesis is a complex syndrome with symptoms that include nausea, vomiting, and postprandial abdominal pain, and is frequently accompanied by significant delays in gastric emptying. The pathophysiology of diabetic gastroparesis is fairly well understood; however, idiopathic gastroparesis, which accounts for one-third of all cases, may stem from infections, or autoimmune or neurologic disorders, among other causes. To date, few population-based studies have estimated the true prevalence and incidence of gastroparesis. Nonetheless, its prevalence appears to be rising, as does its incidence among minority populations, documented via hospitalizations, which can impose significant economic burdens on patients.

Gut reaction: impact of systemic diseases on gastrointestinal physiology and drug absorption

It was in 400 BC that Hippocrates reportedly stated that "death sits in the colon". The growth in our knowledge of the intestinal microbiome, the gut-brain axis and their function and imbalance has distinctly uncovered the complex relationship between the gut to disease predisposition and development, heralding the problem and the solution to disease pathology. Human studies of new drug molecules are typically performed in healthy volunteers and their specific disease indication. Approved drugs, however, are used by patients with diverse disease backgrounds. Here, we review the current literature of the gastrointestinal tract reacting to systemic disease pathology that elicits physiological and functional changes that consequently affect oral drug product performance.

Gastrointestinal Dysfunction in Parkinson's Disease

PURPOSE OF REVIEW

During the past 25 years, there has been an explosion of information regarding the occurrence of gastrointestinal dysfunction in Parkinson's disease. In this review, the clinical features of gastrointestinal dysfunction in Parkinson's disease will be described and information regarding the potential role of the enteric nervous system and the gut microbiome in the genesis of Parkinson's disease will be addressed.

RECENT FINDINGS

Recognition is growing regarding the role that gastroparesis and small intestinal dysfunction may play in Parkinson's disease, especially with regard to erratic responses to anti-Parkinson medication. The presence of enteric nervous system involvement in Parkinson's disease is now well established, but whether the enteric nervous system is the starting point for Parkinson's disease pathology remains a source of debate. The potential role of the gut microbiome also is beginning to emerge. Gastrointestinal dysfunction is a prominent nonmotor feature of Parkinson's disease and dysfunction can be found along the entire length of the gastrointestinal tract. The enteric nervous system is clearly involved in Parkinson's disease. Whether it is the initial source of pathology is still a source of controversy. There also is growing recognition of the role that the gut microbiome may play in Parkinson's disease, but much more research is needed to fully assess this aspect of the disorder.

Manifestations and Outcomes of Patients with Parkinson's Disease and Serious Infection in the Emergency Department

BACKGROUND

Several comorbidities contribute to an increased risk of infections in Parkinson's disease (PD) as the disease progresses. However, few studies have examined the correlation between sepsis and PD.

AIM

The aim of this study is to disclose the presentation and outcome of serious infection in patients with PD in the emergency department.

METHODS

This retrospective cohort study enrolled patients with PD who had serious infection and were admitted to the emergency department between January 2007 and December 2013. For clinical comparison, we compared the clinical features, laboratory data, and outcomes with those of age- and sex-matched patients who had serious infection but not PD.

RESULTS

There were a total of 1,200 episodes of infected PD patients and 2,400 age- and sex-matched infected patients without PD as disease controls. PD patients had fewer comorbidities and lower severity of infectious disease but longer hospital stays than control group patients. The incidences of respiratory tract and urinary tract infections were higher in PD patients. The levels of inflammatory and organ dysfunction biomarkers in PD were lower and compatible with the severity of infectious disease. A total of 86 (7.2%) infected PD patients died during the 28-day admission compared to 339 (14.1%) in non-PD patients. Serum C-reactive protein, bandemia, and lactate could be used to predict mortality in infected PD patients.

CONCLUSIONS

In infected patients with PD, respiratory and urinary tract infections were the two most common infectious sources. Empiric therapy based on experience could treat both respiratory and urinary tract infections. Early diagnosis and treatment are essential for survival.

Dopamine transporter availability reflects gastrointestinal dysautonomia in early Parkinson disease

BACKGROUND

Constipation is a prodromal feature of Parkinson's disease (PD) and the gastrointestinal (GI) tract is implicated in the pathogenesis of PD. However, no studies have demonstrated ante-mortem relationships between nigrostriatal dysfunction and GI dysautonomia in PD.

METHODS

The Scale for Outcomes in Parkinson's disease for Autonomic Symptoms (SCOPA-AUT) assesses dysautonomia in the multi-center Parkinson's Progression Marker Initiative (PPMI). We used linear mixed-effects models and reliable change indices (RCIs) to examine longitudinal associations between dysautonomia and dopamine transporter (DAT) striatal binding ratios (SBRs) measured by single-photon emission computerized tomography in PPMI participants over four years (n = 397 at baseline).

RESULTS

Adjusted mixed-models of longitudinal data showed that constipation-but not orthostatic hypotension or urinary dysfunction-was associated with reduced SBR in both caudate (P < 0.001) and putamen (P = 0.040). In both regions, SBR reductions between baseline and 4-year follow-up were significant and measurable (P < 0.0001), with larger decline and variance in the caudate nucleus. Four-year change in caudate-but not putaminal-SBR was significantly associated with RCI-indicated progression of GI dysautonomia (P = 0.031), but not other types of dysautonomia. These associations remained after adjusting for the use of medications or supplements to control constipation. Consistent with prior PPMI reports, motor impairment progression was not associated with SBR reduction.

CONCLUSIONS

GI dysautonomia correlates with reductions in DAT availability; constipation is most closely associated with caudate-DAT reduction. Worsening GI-dysautonomia and reduced bowel movements may accompany advancing nigral degeneration or changes in nigrostriatal dopamine function.

Gut bacterial composition in a mouse model of Parkinson’s disease

The mechanism of neurodegeneration in Parkinson’s disease (PD) remains unknown but it has been hypothesised that the intestinal tract could be an initiating and contributing factor to the neurodegenerative processes. In PD patients as well as in animal models for PD, alpha-synuclein-positive enteric neurons in the colon and evidence of colonic inflammation have been demonstrated. Moreover, several studies reported pro-inflammatory bacterial dysbiosis in PD patients. Here, we report for the first time significant changes in the composition of caecum mucosal associated and luminal microbiota and the associated metabolic pathways in a rotenone-induced mouse model for PD. The mouse model for PD, induced by the pesticide rotenone, is associated with an imbalance in the gut microbiota, characterised by a significant decrease in the relative abundance of the beneficial commensal bacteria genus Bifidobacterium. Overall, intestinal bacterial dysbiosis might play an important role in both the disruption of intestinal epithelial integrity and intestinal inflammation, which could lead or contribute to the observed alpha-synuclein aggregation and PD pathology in the intestine and central nervous system in the oral rotenone mouse model of PD.

Additive Effects of Levodopa and a Neurorestorative Diet in a Mouse Model of Parkinson's Disease

Though Parkinson’s disease (PD) clinical picture is generally dominated by motor impairment, non-motor symptoms, such as cognitive decline and gastrointestinal dysfunctions, may develop before motor symptoms and have major effects on quality of life. L-3,4-di-hydroxy-phenylalanine (Levodopa) is the most commonly used treatment of motor symptoms but has serious side-effects with prolonged use and does not stop the degenerative process. Moreover, gastrointestinal dysfunctions interfere with the absorption of levodopa and modify its effectiveness. Since most patients are on levodopa treatment, there is a need for combinational therapies that allow for an effective reduction of both motor and non-motor symptoms. We have recently shown that a diet containing precursors and cofactors required for membrane phospholipid synthesis, as well as prebiotic fibers, had therapeutic effects in a PD mouse model. We now investigate the effects of combined administration of the same diet together with levodopa in the rotenone model of PD. Mice were injected with rotenone or vehicle in the striatum. The dietary intervention started after full induction of motor symptoms. The effects of dietary intervention and oral treatment with different doses of levodopa were assessed weekly. Motor and cognitive functions were tested, intestinal transit was analyzed and histological examination of the brain and the colon was assessed. Our results confirm our previous findings that rotenone-induced motor and non-motor problems were alleviated by the Active diet (AD). Levodopa showed an additive beneficial effect on rotarod performance in rotenone-treated animals fed with the AD. No negative interaction effects were found between the AD and levodopa. Our findings suggest that the dietary intervention might confer additional clinical benefits on patients receiving levodopa treatment.

Peripheral and central autonomic nervous system: does the sympathetic or parasympathetic nervous system bear the brunt of the pathology during the course of sporadic PD?

It is a well-established fact that the sympathetic, parasympathetic and enteric nervous systems are affected at early stages in Parkinson's disease (PD). However, it is not yet clarified whether the earliest pathological events preferentially occur in any of these three divisions of the autonomic nervous system (ANS). Significant involvement of the peripheral autonomic nervous system of the heart and gastrointestinal tract has been documented in PD. Accumulating evidence suggests that the PD pathology spreads centripetally from the peripheral to central nervous system through autonomic nerve fibers, implicating the ANS as a major culprit in PD pathogenesis and a potential target for therapy. This study begins with a brief overview of the structures of the central and peripheral autonomic nervous system and then outlines the major clinicopathological manifestations of cardiovascular and gastrointestinal disturbances in PD.

Motor subtypes and other risk factors associated with drooling in Parkinson's disease patients

OBJECTIVE

To explore the relationship between motor subtypes and drooling, and other risk factors associated with drooling in a large cohort of Chinese patients with Parkinson's disease (PD).

METHODS

A total of 586 PD patients were enrolled in this study. Unified Parkinson's disease rating scale (UPDRS) and Hoehn & Yahr stage (H & Y stage) scale, Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), Hamilton Rating Scale for Depression-24 item (HRSD), and Mini-Mental State Examination (MMSE) were applied to all subjects. Salivary subscores of UPDRS part II were used to evaluate drooling. Constipation was diagnosed using the Rome III criteria.

RESULTS

The prevalence of drooling in this cohort is 54.6% (320/586). Non-TD subtype PD patients tend to have higher daily levodopa-equivalent dose (LED), H & Y stage, UPDRS I, UPDRS II, and UPDRS III scores, HRSD score and ESS score, a higher percentage of levodopa treatment, drooling, dyskinesia, and constipation. After adjusting for confounders, non-TD subtype, male sex, UPDRS III score, ESS and PSQI scores, and constipation were still associated with drooling, with corresponding Odds ratios and 95% confidence intervals (95% CIs) were 1.865 (95% CI, 1.137-3.060), 1. 951 (95% CI, 1.326-2.869), 1.024 (95% CI, 1.002-1.046), 1.064 (95% CI, 1.024-1.105), 1.058 (95% CI, 1.000-1.119), and 1.603 (95% CI, 1.092-2.353), respectively.

CONCLUSION

Drooling is common, even in mild-to-moderate PD patients. PD patients with non-TD subtype are at a higher risk of drooling. Male sex, motor severity, excessive daytime sleepiness, poor nighttime sleep, and constipation are also associated with drooling in patients with PD.

Treatment of autonomic dysfunction in Parkinson disease and other synucleinopathies

Dysfunction of the autonomic nervous system afflicts most patients with Parkinson disease and other synucleinopathies such as dementia with Lewy bodies, multiple system atrophy, and pure autonomic failure, reducing quality of life and increasing mortality. For example, gastrointestinal dysfunction can lead to impaired drug pharmacodynamics causing a worsening in motor symptoms, and neurogenic orthostatic hypotension can cause syncope, falls, and fractures. When recognized, autonomic problems can be treated, sometimes successfully. Discontinuation of potentially causative/aggravating drugs, patient education, and nonpharmacological approaches are useful and should be tried first. Pathophysiology-based pharmacological treatments that have shown efficacy in controlled trials of patients with synucleinopathies have been approved in many countries and are key to an effective management. Here, we review the treatment of autonomic dysfunction in patients with Parkinson disease and other synucleinopathies, summarize the nonpharmacological and current pharmacological therapeutic strategies including recently approved drugs, and provide practical advice and management algorithms for clinicians, with focus on neurogenic orthostatic hypotension, supine hypertension, dysphagia, sialorrhea, gastroparesis, constipation, neurogenic overactive bladder, underactive bladder, and sexual dysfunction. © 2018 International Parkinson and Movement Disorder Society.

Induction of alpha-synuclein pathology in the enteric nervous system of the rat and non-human primate results in gastrointestinal dysmotility and transient CNS pathology

Alpha-Synuclein (α-syn) is by far the most highly vetted pathogenic and therapeutic target in Parkinson's disease. Aggregated α-syn is present in sporadic Parkinson's disease, both in the central nervous system (CNS) and peripheral nervous system (PNS). The enteric division of the PNS is of particular interest because 1) gastric dysfunction is a key clinical manifestation of Parkinson's disease, and 2) Lewy pathology in myenteric and submucosal neurons of the enteric nervous system (ENS) has been referred to as stage zero in the Braak pathological staging of Parkinson's disease. The presence of Lewy pathology in the ENS and the fact that patients often experience enteric dysfunction before the onset of motor symptoms has led to the hypothesis that α-syn pathology starts in the periphery, after which it spreads to the CNS via interconnected neural pathways. Here we sought to directly test this hypothesis in rodents and non-human primates (NHP) using two distinct models of α-syn pathology: the α-syn viral overexpression model and the preformed fibril (PFF) model. Subjects (rat and NHP) received targeted enteric injections of PFFs or adeno-associated virus overexpressing the Parkinson's disease associated A53T α-syn mutant. Rats were evaluated for colonic motility monthly and sacrificed at 1, 6, or 12 months, whereas NHPs were sacrificed 12 months following inoculation, after which the time course and spread of pathology was examined in all animals. Rats exhibited a transient GI phenotype that resolved after four months. Minor α-syn pathology was observed in the brainstem (dorsal motor nucleus of the vagus and locus coeruleus) 1 month after PFF injections; however, no pathology was observed at later time points (nor in saline or monomer treated animals). Similarly, a histopathological analysis of the NHP brains revealed no pathology despite the presence of robust α-syn pathology throughout the ENS which persisted for the entirety of the study (12 months). Our study shows that induction of α-syn pathology in the ENS is sufficient to induce GI dysfunction. Moreover, our data suggest that sustained spread of α-syn pathology from the periphery to the CNS and subsequent propagation is a rare event, and that the presence of enteric α-syn pathology and dysfunction may represent an epiphenomenon.

Microbes Tickling Your Tummy: the Importance of the Gut-Brain Axis in Parkinson's Disease

Purpose of Review

Patients suffering from Parkinson's disease (PD) are known to experience gastrointestinal dysfunction that might precede the onset of motor symptoms by several years. Evidence suggests an important role of the gut-brain axis in PD pathogenesis. These interactions might be essentially influenced by the gut microbiota. Here, we review recent findings supporting that changes in the gut microbiota composition might be a trigger for inflammation contributing to neurodegeneration in PD.

Recent Findings

Recent research revealed that PD patients exhibit a pro-inflammatory microbiota profile in their intestinal tract that might increase gut permeability, allowing leakage of bacterial products and inflammatory mediators from the intestines. Evidence in literature indicates that alpha-synuclein deposition might start in the enteric nervous system by pro-inflammatory immune activity and then propagates to the CNS. Alternatively, the peripheral inflammatory response could impact the brain through systemic mechanisms.

Summary

A better understanding of the gut-brain interactions and the role of the intestinal microbiota in the regulation of immune responses might bring new insights in PD pathological progression and might lead to novel diagnostics and therapeutic approaches.

Effect of an impaired oral stage on swallowing in patients with Parkinson's disease

We investigated the swallowing function in patients with Parkinson's disease (PD) using deteriorated tongue control because patients with PD frequently exhibit an impaired oral stage of swallowing and the tongue movement affects oral and pharyngeal stage. In total, 201 patients with PD (106 men, 95 women; mean age 70·6 ± 8·0 years; median Hoehn-Yahr Stage III) were studied. The patients swallowed 10 mL of liquid barium under videofluorography, and their oral transit time (OTT) was measured. Based on 20 healthy controls (mean age 70·3 ± 7·8 years) with an OTT + 2 standard deviation (0·89 + 2 × 0·46) of 1·81 s, the patients with PD were divided into 167 patients with an OTT < 1·81 s and 34 patients with an OTT ≥ 1·81 s. Swallowing function was compared between the groups and assessed using logistic regression analysis. The following factors were significantly associated with oral stage impairment in both groups: tongue-to-palate contact, tongue root-to-posterior pharyngeal wall contact, premature spillage into the pharynx, aspiration and onset of swallowing reflex. Logistic regression analysis showed that tongue root-to-posterior pharyngeal wall contact, onset of swallowing reflex and aspiration were independent factors. PD patients with prolonged OTT displayed poor lingual control and decreased range of motion of the tongue due to bradykinesia and rigidity. Such problems in the oral stage affected the subsequent pharyngeal stage of swallowing with aspiration. Lingual movement in the oral stage thus appears to play an important role in the sequential movement of swallowing in PD.

Assessments of plasma ghrelin levels in the early stages of parkinson's disease

BACKGROUND

Gastrointestinal symptoms are early events in Parkinson's disease (PD). The gastrointestinal hormone ghrelin was neuroprotective in the nigrostriatal dopamine system. The objective of this study was to assess ghrelin levels in the early stages of PD.

METHODS

Plasma was collected in the fasting state in 291 PD patients in stages 1-3 and 303 age- and sex-matched healthy controls. Additional samples were taken in the glucose response test to assess nutrition-related ghrelin levels in 20 PD patients and 20 healthy controls. The enzyme-linked immunosorbent assay was used to measure total and active plasma ghrelin levels.

RESULTS

We reported that total and active plasma ghrelin levels were decreased in PD, although there was no difference across progressive PD stages. Postprandial ghrelin suppression and preprandial peak responses were both attenuated in PD.

CONCLUSIONS

Plasma ghrelin levels were decreased in PD; however, this event might be irrelevant to PD progression. Ghrelin responses to meals were also impaired in PD. © 2017 International Parkinson and Movement Disorder Society.

The Gut and Nonmotor Symptoms in Parkinson's Disease

Gastrointestinal (GI) symptoms are one of the most common nonmotor symptoms (NMS) in patients with Parkinson's disease (PD) involving the whole GI tract (GIT) and being evident throughout the whole course of the disease. Furthermore, constipation serves as a risk factor for PD as well as an early prodromal NMS of PD. The gut as gateway to the environment with its enteric nervous system (ENS) plays a crucial role in the neurodegenerative process that leads to PD. Alpha-synucleinopathy as the pathological hallmark of PD could be found within the whole GIT in a rostrocaudal gradient interacting with the ENS, the gut microbiome, and enteric glial cells. Bidirectional interactions between the ENS and the central nervous system (CNS) via a brain-gut-enteric microbiota axis have been reported. As well as there is evidence out of animal, autopsy, and epidemiological studies that α-synuclein spreads via rostrocranial transmission by transsynaptic cell-to-cell transfer via the sympathetic and parasympathetic nervous system to the CNS causing the typical neuropathological changes of PD. Recognition of GI NMS as prodromal markers of PD as well as a better understanding of the brain-gut connection offers new insights in the pathophysiology of PD and might provide the opportunity of PD diagnosis before CNS involvement. Hereby the opportunity for development of neuroprotective and disease-modifying therapeutics, respectively, seem to be promising. This chapter covers the variety of GI NMS and its consequences in PD as well as the important role of the gut as part of the pathological process in PD.

Imaging the Nonmotor Symptoms in Parkinson's Disease

Parkinson's disease is acknowledged to be a multisystem syndrome, manifesting as a result of multineuropeptide dysfunction, including dopaminergic, cholinergic, serotonergic, and noradrenergic deficits. This multisystem disorder ultimately leads to the presentation of a range of nonmotor symptoms, now appreciated to be an integral part of the disease-specific spectrum of symptoms, often preceding the diagnosis of motor Parkinson's disease. In this chapter, we review the dopaminergic and nondopaminergic basis of these symptoms by exploring the neuroimaging evidence based on several techniques including positron emission tomography, single-photon emission computed tomography molecular imaging, magnetic resonance imaging, functional magnetic resonance imaging, and diffusion tensor imaging. We discuss the role of these neuroimaging techniques in elucidating the underlying pathophysiology of NMS in Parkinson's disease.

Imaging Parkinson's disease below the neck

Parkinson's disease is a systemic disorder with widespread and early α-synuclein pathology in the autonomic and enteric nervous systems, which is present throughout the gastrointestinal canal prior to diagnosis. Gastrointestinal and genitourinary autonomic symptoms often predate clinical diagnosis by several years. It has been hypothesized that progressive α-synuclein aggregation is initiated in hyperbranched, non-myelinated neuron terminals, and may subsequently spread via retrograde axonal transport. This would explain why autonomic nerves are so prone to formation of α-synuclein pathology. However, the hypothesis remains unproven and in vivo imaging methods of peripheral organs may be essential to study this important research field. The loss of sympathetic and parasympathetic nerve terminal function in Parkinson's disease has been demonstrated using radiotracers such as 123I-meta-iodobenzylguanidin, 18F-dopamine, and 11C-donepezil. Other radiotracer and radiological imaging methods have shown highly prevalent dysfunction of pharyngeal and esophageal motility, gastric emptying, colonic transit time, and anorectal function. Here, we summarize the methodology and main findings of radio-isotope and radiological modalities for imaging peripheral pathology in Parkinson's disease.

Promising Effects of Neurorestorative Diets on Motor, Cognitive, and Gastrointestinal Dysfunction after Symptom Development in a Mouse Model of Parkinson's Disease

Parkinson's disease (PD) is characterized by the progressive degeneration of dopaminergic nigrostriatal neurons, with reductions in the function and amount of dopaminergic synapses. Therefore, synapse loss and membrane-related pathology provide relevant targets for interventions in PD. We previously showed the beneficial preventive effects of a dietary intervention containing uridine and DHA, two precursors for membrane synthesis, in the intrastriatal rotenone model for PD. Here, we examined the therapeutic potential of the same dietary intervention on motor, cognitive, and gastrointestinal symptoms. In addition, we tested the effects of an extended nutritional formula based on the same precursors plus other nutrients that increase membrane phospholipid synthesis as well as prebiotic fibers. C57BL/6J mice received a unilateral rotenone injection in the striatum. Dietary interventions started 28 days after surgery, when motor-symptoms had developed. Readout parameters included behavioral tasks measuring motor function and spatial memory as well as intestinal function and histological examination of brain and gut to assess PD-like pathology. Our results show that rotenone-induced motor and non-motor problems were partially alleviated by the therapeutic dietary interventions providing uridine and DHA. The extended nutritional intervention containing both precursors and other nutrients that increase phospholipid synthesis as well as prebiotic fibers was more effective in normalizing rotenone-induced motor and non-motor abnormalities. The latter diet also restored striatal DAT levels, indicating its neurorestorative properties. This is the first study demonstrating beneficial effects of specific dietary interventions, given after full development of symptoms, on a broad spectrum of motor and non-motor symptoms in a mouse model for PD.

Gut-brain and brain-gut axis in Parkinson's disease models: Effects of a uridine and fish oil diet

Recent investigations have focused on the potential role of gastrointestinal (GI) abnormalities in the pathogenesis of Parkinson's disease (PD). The 'dual-hit' hypothesis of PD speculates that a putative pathogen enters the brain via two routes: the olfactory system and the GI system. Here, we investigated (1) whether local exposures of the neurotoxin rotenone in the gut or the brain of mice could induce PD-like neurological and GI phenotypes as well as a characteristic neuropathology in accordance with this 'dual-hit hypothesis' and (2) the effects of a diet containing uridine and fish oil providing docosahexaenoic acid (DHA), in both models. Mice were given rotenone either orally or by an injection in the striatum. Dietary interventions were started 1 week before rotenone exposures. We found that (1) both oral and intrastriatal administration of rotenone induced similar PD-like motor deficits, dopaminergic cell loss, delayed intestinal transit, inflammation, and alpha-synuclein accumulation in the colon; (2) the uridine and DHA containing diet prevented rotenone-induced motor and GI dysfunctions in both models. The models suggest possible bidirectional communication between the gut and the brain for the genesis of PD-like phenotype and pathology. The dietary intervention may provide benefits in the prevention of motor and non-motor symptoms in PD.

A randomized trial of relamorelin for constipation in Parkinson's disease (MOVE-PD): Trial results and lessons learned

BACKGROUND

Bowel dysfunction, including both slow transit constipation and defecatory dysfunction, is a frequent and often troubling nonmotor manifestation of Parkinson's disease (PD). A variety of agents are employed for the treatment of constipation in PD, but dissatisfaction with available treatment approaches is common. Relamorelin is a synthetic ghrelin agonist that has demonstrated prokinetic properties within the gastrointestinal tract.

METHODS

We carried out a multi-center, randomized, double-blind, placebo-controlled study of relamorelin in patients with PD experiencing chronic, inadequately controlled constipation.

RESULTS

Only 18 of an intended 56 subjects completed the trial, in part because of the unexpected occurrence of multiple partially complete bowel movements in constipated PD patients, which made many subjects ineligible for participation.

CONCLUSIONS

Although recruitment goals were not met, which precluded demonstration of any potential beneficial effect of relamorelin, unique and important insights with regard to the nature of constipation in PD were recognized, which hopefully will lead to more effective clinical trials in the future. It is clear that what PD patients understand as constipation may be more complex than previously realized and does not appear to be characterized by decreased stool frequency alone.

Exploring Braak's Hypothesis of Parkinson's Disease

Parkinson’s disease (PD) is a neurodegenerative disorder for which there is no cure. Most patients suffer from sporadic PD, which is likely caused by a combination of genetic and environmental factors. Braak’s hypothesis states that sporadic PD is caused by a pathogen that enters the body via the nasal cavity, and subsequently is swallowed and reaches the gut, initiating Lewy pathology (LP) in the nose and the digestive tract. A staging system describing the spread of LP from the peripheral to the central nervous system was also postulated by the same research group. There has been criticism to Braak’s hypothesis, in part because not all patients follow the proposed staging system. Here, we review literature that either supports or criticizes Braak’s hypothesis, focused on the enteric route, digestive problems in patients, the spread of LP on a tissue and a cellular level, and the toxicity of the protein αSynuclein (αSyn), which is the major constituent of LP. We conclude that Braak’s hypothesis is supported by in vitro, in vivo, and clinical evidence. However, we also conclude that the staging system of Braak only describes a specific subset of patients with young onset and long duration of the disease.

Presynaptic dopaminergic terminal imaging and non-motor symptoms assessment of Parkinson's disease: evidence for dopaminergic basis?

Parkinson's disease (PD) is now considered to be a multisystemic disorder consequent on multineuropeptide dysfunction including dopaminergic, serotonergic, cholinergic, and noradrenergic systems. This multipeptide dysfunction leads to expression of a range of non-motor symptoms now known to be integral to the concept of PD and preceding the diagnosis of motor PD. Some non-motor symptoms in PD may have a dopaminergic basis and in this review, we investigate the evidence for this based on imaging techniques using dopamine-based radioligands. To discuss non-motor symptoms we follow the classification as outlined by the validated PD non-motor symptoms scale.

Gastrointestinal dysfunction in idiopathic Parkinsonism: A narrative review

Currently, gastrointestinal (GI) dysfunctions in Parkinson's disease (PD) are well-recognized problems and are known to be the initial symptoms in the pathological process that eventually results in PD. Many types of PD-associated GI dysfunctions have been identified, including weight loss, nausea, hypersalivation, dysphagia, dyspepsia, abdominal pain, intestinal pseudo-obstruction, constipation, defecatory dysfunction, and small intestinal bacterial overgrowth. These symptoms can influence on other PD symptoms and are the second most significant predictor of the quality of life of these patients. Recognition of GI symptoms requires vigilance on the part of clinicians. Health-care providers should routinely ask direct questions about GI symptoms during office visits so that efforts can be directed at appropriate management of these distressing manifestations. Multiple system atrophy (MSA) and progressive supranuclear palsy are two forms of neurodegenerative Parkinsonism. Symptoms of autonomic dysfunctions such as GI dysfunction are common in patients with parkinsonian disorders. Despite recent progress in the recognition of GI dysfunctions, there are a few reviews on the management of GI dysfunction and GI symptoms in idiopathic Parkinsonism. In this review, the clinical presentation, pathophysiology, and treatment of each GI symptom in PD, MSA, and prostate-specific antigen will be discussed.