Constipation in parkinson's disease: Subjective symptoms, objective markers, and new perspectives

Acupuncture for constipation in Parkinson's disease: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Parkinson's disease (PD) is the second most common neurological disease worldwide, and there is a potential interaction between PD and constipation. PD constipation often causes significant trouble for patients and seriously affects their quality of life. Acupuncture is widely used for treating constipation and has been clinically proven. However, it is unclear whether the current evidence is sufficient to support acupuncture to improve PD constipation.

METHODS

We searched the Cochrane Central Register of Controlled Trials, Embase, PubMed, Web of Science, China National Knowledge Infrastructure, Wan Fang Data Knowledge Service Platform, and Chinese Scientific Journal Database (VIP database) for randomized controlled trials from inception through July 1, 2023. Randomized controlled trials (RCTs) included acupuncture, sham acupuncture, and medication for PD constipation. Stata 16.0 software and Cochrane RoB2.0 were used for data processing and migration risk analysis.

RESULTS

The 11 studies included a total of 960 patients. The results showed that acupuncture or acupuncture combined with conventional treatment seemed to have advantages in improving complete spontaneous bowel movements (WMD: 1.49, 95% CI: 0.86, 2.11; P < .00001), Patient-Assessment of Constipation Quality of Life questionnaire (WMD: -11.83, 95% CI: -15.67, -7.99; P < .00001), the chronic constipation severity scale (CCS) (SMD: -0.99, 95% CI: -1.40, -0.58; P < .01), and c(RRP) (WMD: 2.13, 95% CI: 0.44, 3.82; P < .05).

CONCLUSION

The present results show that compared with conventional treatment, acupuncture combined with conventional treatment seems to increase the number of spontaneous defecations in PD patients, improve quality of life, increase rectal resting pressure, and alleviate the severity of chronic constipation. Thus, acupuncture has the potential to treat PD constipation. However, due to the study's limitations, higher-quality RCTs are needed for verification.

Consensus practice recommendations for management of gastrointestinal dysfunction in Parkinson disease

BACKGROUND

Gastrointestinal (GI) dysfunction is a common non-motor feature of Parkinson disease (PD). GI symptoms may start years before the onset of motor symptoms and impair quality of life. Robust clinical trial data is lacking to guide screening, diagnosis and treatment of GI dysfunction in PD.

OBJECTIVE

To develop consensus statements on screening, diagnosis, and treatment of GI dysfunction in PD.

METHODS

The application of a modified Delphi panel allowed for the synthesis of expert opinions into clinical statements. Consensus was predefined as a level of agreement of 100 % for each item. Five virtual Delphi rounds were held. Two movement disorders neurologists reviewed the literature on GI dysfunction in PD and developed draft statements based on the literature review. Draft statements were distributed among the panel that included five movement disorder neurologists and two gastroenterologists, both experts in GI dysmotility and its impact on PD symptoms. All members reviewed the statements and references in advance of the virtual meetings. In the virtual meetings, each statement was discussed, edited, and a vote was conducted. If there was not 100 % consensus, further discussions and modifications ensued until there was consensus.

RESULTS

Statements were developed for screening, diagnosis, and treatment of common GI symptoms in PD and were organized by anatomic segments: oral cavity and esophagus, stomach, small intestine, and colon and anorectum.

CONCLUSIONS

These consensus recommendations offer a practical framework for the diagnosis and treatment of GI dysfunction in PD.

Defecatory disorders are a common cause of chronic constipation in Parkinson disease

BACKGROUND AND AIMS

Up to 50% of patients with Parkinson disease have constipation (PD-C), but the prevalence of defecatory disorders caused by rectoanal dyscoordination in PD-C is unknown. We aimed to compare anorectal function of patients with PD-C versus idiopathic chronic constipation (CC).

METHODS

Anorectal pressures, rectal sensation, and rectal balloon expulsion time (BET) were measured with high-resolution anorectal manometry (HR-ARM) in patients with PD-C and control patients with CC, matched for age and sex.

RESULTS

We identified 97 patients with PD-C and 173 control patients. Eighty-six patients with PD-C (89%) had early PD, and 39 (40%) had a defecatory disorder, manifest by a prolonged rectal balloon expulsion time (37 patients) or a lower rectoanal pressure difference during evacuation (2 patients). PD-C patients with a prolonged BET had a greater anal resting pressure (p = 0.02), a lower rectal pressure increment (p = 0.005), greater anal pressure (p = 0.047), and a lower rectoanal pressure difference during evacuation (p < 0.001). Rectal sensory thresholds were greater in patients with abnormal BET. In the multivariate model comparing CC and PD-C (AUROC = 0.76), PD-C was associated with a lower anal squeeze increment (odds ratio [OR] for PD-C, 0.93 [95% CI, 0.91-0.95]), longer squeeze duration (OR, 1.05 [95% CI, 1.03-1.08]), lower rectal pressure increment (OR per 10 mm Hg, 0.72 [95% CI, 0.66-0.79]), and negative rectoanal gradient during evacuation (OR per 10 mm Hg, 1.16 [95% CI, 1.08-1.26]).

CONCLUSIONS

Compared with CC, PD-C was characterized by impaired squeeze pressure, longer squeeze duration, lower increase in rectal pressure, and a more negative rectoanal gradient during evacuation.

Safety and efficacy of faecal microbiota transplantation in patients with mild to moderate Parkinson's disease (GUT-PARFECT): a double-blind, placebo-controlled, randomised, phase 2 trial

Background

Dysregulation of the gut microbiome has been implicated in Parkinson's disease (PD). This study aimed to evaluate the clinical effects and safety of a single faecal microbiota transplantation (FMT) in patients with early-stage PD.

Methods

The GUT-PARFECT trial, a single-centre randomised, double-blind, placebo-controlled trial was conducted at Ghent University Hospital between December 01, 2020 and December 12, 2022. Participants (aged 50-65 years, Hoehn and Yahr stage 2) were randomly assigned to receive nasojejunal FMT with either healthy donor stool or their own stool. Computer-generated randomisation was done in a 1:1 ratio through permutated-block scheduling. Treatment allocation was concealed for participants and investigators. The primary outcome measure at 12 months was the change in the Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) motor score obtained during off-medication evaluations. Intention-to-treat analysis was performed using a mixed model for repeated measures analysis. This completed trial is registered on ClinicalTrials.gov (NCT03808389).

Findings

Between December 2020 and December 2021, FMT procedures were conducted on 46 patients with PD: 22 in the healthy donor group and 24 in the placebo group. Clinical evaluations were performed at baseline, 3, 6, and 12 months post-FMT. Full data analysis was possible for 21 participants in the healthy donor group and 22 in the placebo group. After 12 months, the MDS-UPDRS motor score significantly improved by a mean of 5.8 points (95% CI -11.4 to -0.2) in the healthy donor group and by 2.7 points (-8.3 to 2.9) in the placebo group (p = 0.0235). Adverse events were limited to temporary abdominal discomfort.

Interpretation

Our findings suggested a single FMT induced mild, but long-lasting beneficial effects on motor symptoms in patients with early-stage PD. These findings highlight the potential of modulating the gut microbiome as a therapeutic approach and warrant a further exploration of FMT in larger cohorts of patients with PD in various disease stages.

Funding

Flemish PD patient organizations (VPL and Parkili), Research Foundation Flanders (FWO), Biocodex Microbiota Foundation.

Relationship among Parkinson's disease, constipation, microbes, and microbiological therapy

This comprehensive review elucidates the complex interplay between gut microbiota and constipation in Parkinson's disease (PD), a prevalent non-motor symptom contributing significantly to patients' morbidity. A marked alteration in the gut microbiota, predominantly an increase in the abundance of Proteobacteria and Bacteroidetes, is observed in PD-related constipation. Conventional treatments, although safe, have failed to effectively alleviate symptoms, thereby necessitating the development of novel therapeutic strategies. Microbiological interventions such as prebiotics, probiotics, and fecal microbiota transplantation (FMT) hold therapeutic potential. While prebiotics improve bowel movements, probiotics are effective in enhancing stool consistency and alleviating abdominal discomfort. FMT shows potential for significantly alleviating constipation symptoms by restoring gut microbiota balance in patients with PD. Despite promising developments, the causal relationship between changes in gut microbiota and PD-related constipation remains elusive, highlighting the need for further research in this expanding field.

Parkinson's Disease and Photobiomodulation: Potential for Treatment

Parkinson's disease is the second most common neurodegenerative disease and is increasing in incidence. The combination of motor and non-motor symptoms makes this a devastating disease for people with Parkinson's disease and their care givers. Parkinson's disease is characterised by mitochondrial dysfunction and neuronal death in the substantia nigra, a reduction in dopamine, accumulation of α-synuclein aggregates and neuroinflammation. The microbiome-gut-brain axis is also important in Parkinson's disease, involved in the spread of inflammation and aggregated α-synuclein. The mainstay of Parkinson's disease treatment is dopamine replacement therapy, which can reduce some of the motor signs. There is a need for additional treatment options to supplement available medications. Photobiomodulation (PBM) is a form of light therapy that has been shown to have multiple clinical benefits due to its enhancement of the mitochondrial electron transport chain and the subsequent increase in mitochondrial membrane potential and ATP production. PBM also modulates cellular signalling and has been shown to reduce inflammation. Clinically, PBM has been used for decades to improve wound healing, treat pain, reduce swelling and heal deep tissues. Pre-clinical experiments have indicated that PBM has the potential to improve the clinical signs of Parkinson's disease and to provide neuroprotection. This effect is seen whether the PBM is directed to the head of the animal or to other parts of the body (remotely). A small number of clinical trials has given weight to the possibility that using PBM can improve both motor and non-motor clinical signs and symptoms of Parkinson's disease and may potentially slow its progression.

Plasma metabolites of aromatic amino acids associate with clinical severity and gut microbiota of Parkinson's disease

Gut microbial proteolytic metabolism has been reportedly altered in Parkinson's disease (PD). However, the circulating aromatic amino acids (AAA) described in PD are inconsistent. Here we aimed to investigate plasma AAA profiles in a large cohort of PD patients, and examine their correlations with clinical severity and gut microbiota changes. We enrolled 500 participants including 250 PD patients and 250 neurologically normal controls. Plasma metabolites were measured using liquid chromatography mass spectrometry. Faecal samples were newly collected from 154 PD patients for microbiota shotgun metagenomic sequencing combined with data derived from 96 PD patients reported before. Data were collected regarding diet, medications, and motor and non-motor symptoms of PD. Compared to controls, PD patients had higher plasma AAA levels, including phenylacetylglutamine (PAGln), p-cresol sulfate (Pcs), p-cresol glucuronide (Pcg), and indoxyl sulfate (IS). Multivariable linear regression analyses, with adjustment for age, sex, and medications, revealed that the plasma levels of PAGln (coefficient 4.49, 95% CI 0.40-8.58, P = 0.032) and Pcg (coefficient 1.79, 95% CI 0.07-3.52, P = 0.042) positively correlated with motor symptom severity but not cognitive function. After correcting for abovementioned potential confounders, these AAA metabolites were also associated with the occurrence of constipation in PD patients (all P < 0.05). Furthermore, plasma levels of AAA metabolites were correlated with the abundance of specific gut microbiota species, including Bacteroides sp. CF01-10NS, Bacteroides vulgatus, and Clostridium sp. AF50-3. In conclusion, elevated plasma AAA metabolite levels correlated with disease characteristics in PD, suggesting that upregulated proteolytic metabolism may contribute to the pathophysiology of PD.

The substantia nigra modulates proximal colon tone and motility in a vagally-dependent manner in the rat

A monosynaptic pathway connects the substantia nigra pars compacta (SNpc) to neurons of the dorsal motor nucleus of the vagus (DMV). This monosynaptic pathway modulates the vagal control of gastric motility. It is not known, however, whether this nigro-vagal pathway also modulates the tone and motility of the proximal colon. In rats, microinjection of retrograde tracers in the proximal colon and of anterograde tracers in SNpc showed that bilaterally labelled colonic-projecting neurons in the DMV received inputs from SNpc neurons. Microinjections of the ionotropic glutamate receptor agonist, NMDA, in the SNpc increased proximal colonic motility and tone, as measured via a strain gauge aligned with the colonic circular smooth muscle; the motility increase was inhibited by acute subdiaphragmatic vagotomy. Upon transfection of SNpc with pAAV-hSyn-hM3D(Gq)-mCherry, chemogenetic activation of nigro-vagal nerve terminals by brainstem application of clozapine-N-oxide increased the firing rate of DMV neurons and proximal colon motility; both responses were abolished by brainstem pretreatment with the dopaminergic D1-like antagonist SCH23390. Chemogenetic inhibition of nigro-vagal nerve terminals following SNpc transfection with pAAV-hSyn-hM4D(Gi)-mCherry decreased the firing rate of DMV neurons and inhibited proximal colon motility. These data suggest that a nigro-vagal pathway modulates activity of the proximal colon motility tonically via a discrete dopaminergic synapse in a manner dependent on vagal efferent nerve activity. Impairment of this nigro-vagal pathway may contribute to the severely reduced colonic transit and prominent constipation observed in both patients and animal models of parkinsonism. KEY POINTS: Substantia nigra pars compacta (SNpc) neurons are connected to the dorsal motor nucleus of the vagus (DMV) neurons via a presumed direct pathway. Brainstem neurons in the lateral DMV innervate the proximal colon. Colonic-projecting DMV neurons receive inputs from neurons of the SNpc. The nigro-vagal pathway modulates tone and motility of the proximal colon via D1-like receptors in the DMV. The present study provides the mechanistic basis for explaining how SNpc alterations may lead to a high rate of constipation in patients with Parkinson's Disease.

Complement C1q-dependent engulfment of alpha-synuclein induces ENS-resident macrophage exhaustion and accelerates Parkinson's-like gut pathology

Deposition of misfolded α-synuclein (αsyn) in the enteric nervous system (ENS) is found in multiple neurodegenerative diseases. It is hypothesized that ENS synucleinopathy contributes to both the pathogenesis and non-motor morbidity in Parkinson's Disease (PD), but the cellular and molecular mechanisms that shape enteric histopathology and dysfunction are poorly understood. Here, we demonstrate that ENS-resident macrophages, which play a critical role in maintaining ENS homeostasis, initially respond to enteric neuronal αsyn pathology by upregulating machinery for complement-mediated engulfment. Pharmacologic depletion of ENS-macrophages or genetic deletion of C1q enhanced enteric neuropathology. Conversely, C1q deletion ameliorated gut dysfunction, indicating that complement partially mediates αsyn-induced gut dysfunction. Internalization of αsyn led to increased endo-lysosomal stress that resulted in macrophage exhaustion and temporally correlated with the progression of ENS pathology. These novel findings highlight the importance of enteric neuron-macrophage interactions in removing toxic protein aggregates that putatively shape the earliest stages of PD in the periphery.

Breaking ground: nursing-led approach to alleviating constipation in Parkinson's disease

BACKGROUND

Constipation is one of the most common non-motor symptoms in PD patients, and the constipation, can appear before motor symptoms. Incorrect treatment of constipation in PD patients can result in colonic volvulus and pseudo intestinal obstruction, as well as a reduction in the therapeutic effect of anti-PD drugs due to absorption issues. There is, however, no comprehensive and scientific nursing intervention plan for PD patients' constipation who are constipated.

METHODS

A multi-disciplinary nursing research group of five people was established to construct the first draft of intervention plan through literature review. We chose 15 experts from 7 universities and tertiary hospitals spread over 5 provinces (cities), including 4 neurologists, 9 clinical nursing specialists in neurology, 1 dietician, and 1 rehabilitator. Two rounds of consultations were held from April to July 2022 with 15 experts to screen and revise the indicators at each level, confirming their importance and feasibility at each level.

RESULTS

There were three primary indicators (pre-intentional stage, intentional stage, and action stage) in the two rounds of expert correspondence, nine secondary indicators (disease risk perception, adverse consequence expectation, self-efficacy and intention of action; action plan, coping plan and coping self-efficacy; produce healthy behaviors, maintain healthy behaviors, recover behaviors and recover self-efficacy), and 22 tertiary indicators.

CONCLUSIONS

After the implementation of two rounds of Delphi method, the final formed constipation intervention program for PD patients provides the basis for clinical nursing practice, which has the characteristics of convenience, comprehensiveness, dependence, scientific and feasibility. Therefore, it has application and promotion value.

Parkinson's disease patients combined with constipation tend to have higher serum expression of microRNA 29c, prominent neuropsychiatric disorders, possible RBD conversion, and a substandard quality of life

INTRODUCTION

The symptom of constipation has been confirmed as an early diagnose criteria for Parkinson's disease (PD). Furthermore, evidences suggest that pathogenesis of PD initiates in gut, rather than brain. If so, identifying biomarkers for constipation in PD might have potentials to assist early diagnosis and initial treatment.

METHOD

We first identified that microRNA 29c (miR-29c) was dysregulated both in PD and constipation patients through bioinformatics analysis. Then, serological analysis of the expression of miR-29c in 67 PD patients with constipation (PD-C), 51 PD patients without constipation (PD-NC), and 50 healthy controls (HC) was carried out by qPCR. Demographic and clinical features were also compared. Patients in PD-C group were further classified into two groups: those with prodromal stage constipation (PD-C-Pro) (n = 36) and those with clinical stage constipation (PD-C-Clinic) (n = 31), to explore their different characteristics.

RESULTS

The levels of miR-29c in PD-C group were higher than that in PD-NC group, both higher than HC group. PD-C-Pro group's miR-29c levels were statistically higher compared with PD-C-Clinic group's. What is more, PD-C group had higher scores of MDS-UPDRS-I, NMSS, NMSS3, NMSS4, NMSS6, NMSS9, SCOPA-AUT, HAMD, HAMA, RBDSQ, CSS, and PACQOL compared with PD-NC party. Relative to the PD-C-Clinic, patients in PD-C-Pro group had higher MDS-UPDRS-I, NMSS, NMSS3, HAMD, and HAMA scores, and were more likely to have RBD.

CONCLUSION

Our results indicated that miR-29c seems to be an underlying cause for developing constipation in patients with PD and PD-C identifies a group of patients with more severe non-motor impairment, prominent neuropsychiatric disorders, and possible RBD conversion as well as a substandard quality of life. We further confirmed that there is a close relationship between symptoms representing the same pathological origin, especially constipation and RBD.

Acupuncture for Parkinson's disease-related constipation: current evidence and perspectives

Parkinson's disease-related constipation (PDC) is commonly associated with impaired dopamine transmission and gastrointestinal dysfunction. Current pharmacological treatments have limited efficacy and potential side effects. Acupuncture has shown promise as an alternative or adjunct therapy by modulating the brain-gut axis, gastrointestinal hormones, and autonomic function. Preliminary randomized trials have shown that acupuncture significantly improves constipation symptoms, bowel movements, and comfort compared to sham or drug treatments and is well-tolerated. The mechanisms of action may involve regulating the gut microbiota and mucosal immunity to improve dysbiosis and gastrointestinal motility. However, more rigorous studies are required to optimize acupuncture protocols and determine long-term efficacy and safety. In summary, acupuncture shows promise as an adjunct therapy for PDC, but further research is needed to confirm its efficacy and safety.

Mutant LRRK2 exacerbates immune response and neurodegeneration in a chronic model of experimental colitis

The link between the gut and the brain in Parkinson's disease (PD) pathogenesis is currently a subject of intense research. Indeed, gastrointestinal dysfunction is known as an early symptom in PD and inflammatory bowel disease (IBD) has recently been recognised as a risk factor for PD. The leucine-rich repeat kinase 2 (LRRK2) is a PD- and IBD-related protein with highest expression in immune cells. In this study, we provide evidence for a central role of LRRK2 in gut inflammation and PD. The presence of the gain-of-function G2019S mutation significantly increases the disease phenotype and inflammatory response in a mouse model of experimental colitis based on chronic dextran sulphate sodium (DSS) administration. Bone marrow transplantation of wild-type cells into G2019S knock-in mice fully rescued this exacerbated response, proving the key role of mutant LRRK2 in immune cells in this experimental colitis model. Furthermore, partial pharmacological inhibition of LRRK2 kinase activity also reduced the colitis phenotype and inflammation. Moreover, chronic experimental colitis also induced neuroinflammation and infiltration of peripheral immune cells into the brain of G2019S knock-in mice. Finally, combination of experimental colitis with overexpression of α-synuclein in the substantia nigra aggravated motor deficits and dopaminergic neurodegeneration in G2019S knock-in mice. Taken together, our results link LRRK2 with the immune response in colitis and provide evidence that gut inflammation can impact brain homeostasis and contribute to neurodegeneration in PD.

Overview of the Gut-Brain Axis: From Gut to Brain and Back Again

The gut-brain axis refers to a bidirectional communication pathway linking the gastrointestinal system to the central nervous system. The hardware of this multifaceted pathway takes many forms, at once structural (neurons, microglia, intestinal epithelial cell barrier), chemical (neurotransmitters, enteroendocrine hormones, bacterial metabolites), and cellular (immune signaling, inflammatory pathways). The gut-brain axis is exquisitely influenced by our environment, diet, and behaviors. Here, we will describe recent progress in understanding the gut-brain axis in neurological disease, using Parkinson's disease as a guide. We will see that each component of the gut-brain axis is heavily mediated by intestinal microbiota and learn how gut-brain communication can go awry in microbial dysbiosis.

Effect of Lacticaseibacillus paracasei strain Shirota supplementation on clinical responses and gut microbiome in Parkinson's disease

Parkinson's disease (PD) is a common neurodegenerative disease characterized by motor issues and a range of non-motor symptoms. Microbial therapy may be a useful approach for the treatment of PD. However, comprehensive analyses of the impact of probiotic supplementation on motor and non-motor symptoms are still lacking and the mechanisms whereby the treatment works remain unclear. This study investigated Lacticaseibacillus paracasei strain Shirota (LcS) supplementation on clinical responses, gut microbiota and faecal metabolites in PD patients. Patients (n = 128) were randomised to receive either probiotics (LcS-fermented milk, containing 1 × 1010 living LcS cells) or placebo for 12 weeks. All participants were examined and the basic clinical features were recorded using questionnaires. Fecal and blood samples were collected at the baseline and after 12 weeks for further omics analysis. We found that LcS intervention significantly alleviated patients' constipation-related symptoms and non-motor symptoms. We found no significant shifts in the composition of gut microbiota or faecal metabolites. Several taxa were differentially abundant between the groups, especially with regard to LcS intake, which increased the abundance of the genus Lacticaseibacillus in the probiotic group compared with those at the baseline and in the placebo group. The faecal concentration of L-tyrosine was significantly decreased and the plasma concentration of L-tyrosine was increased in the probiotic group compared with the placebo group. Our study demonstrated that although supplementation with LcS did not induce major changes in the global gut microbiome, the probiotic had favorable effects in managing constipation and other non-motor symptoms in PD patients. This study was registered at the Chinese Clinical Trial Registry: ChiCTR1800016795.

Sex and Age Differences in a Progressive Synucleinopathy Mouse Model

The mutation and overexpression of the alpha-synuclein protein (αSyn), described as synucleinopathy, is associated with Parkinson's disease (PD)-like pathologies. A higher prevalence of PD is documented for men versus women, suggesting female hormones' implication in slowing PD progression. The nigrostriatal dopamine (DA) neurons in rodent males are more vulnerable to toxins than those in females. The effect of biological sex on synucleinopathy remains poorly described and was investigated using mice knocked out for murine αSyn (SNCA-/-) and also overexpressing human αSyn (SNCA-OVX) compared to wildtype (WT) mice. All the mice showed decreased locomotor activity with age, and more abruptly in the male than in the female SNCA-OVX mice; anxiety-like behavior increased with age. The SNCA-OVX mice had an age-dependent accumulation of αSyn. Older age was associated with the loss of nigral DA neurons and decreased striatal DA contents. The astrogliosis, microgliosis, and cytokine concentrations increased with aging. More abrupt nigrostriatal DA decreases and increased microgliosis were observed in the male SNCA-OVX mice. Human αSyn overexpression and murine αSyn knockout resulted in behavioral dysfunctions, while only human αSyn overexpression was toxic to DA neurons. At 18 months, neuroprotection was lost in the female SNCA-OVX mice, with a likely loss of estrus cycles. In conclusion, sex-dependent αSyn toxicity was observed, affecting the male mice more significantly.

Constipation in multiple system atrophy: a pilot study in Chinese patients

Objective

This study aimed to investigate the prevalence and clinical characteristics of subjective constipation in Chinese patients with multiple system atrophy (MSA), as well as the timing of constipation onset relative to the occurrence of motor symptoms.

Methods

A total of 200 patients who were consecutively admitted to two large Chinese hospitals from February 2016 to June 2021 and subsequently diagnosed with probable MSA were enrolled in this cross-sectional study. Demographic and constipation-related clinical data were collected, and motor and non-motor symptoms were assessed using various scales and questionnaires. Subjective constipation was defined using ROME III criteria.

Results

The frequency of constipation was 53.5, 59.7, and 39.3% in MSA, MSA with predominately parkinsonism (MSA-P), and MSA with predominately cerebellar ataxia (MSA-C), respectively. MSA-P subtype and high total UMSARS scores were associated with constipation in MSA. Similarly, the high total UMSARS scores were associated with constipation in MSA-P and MSA-C patients. Among the 107 patients with constipation, 59.8% began experiencing it before the onset of motor symptoms, and the interval between constipation and occurrence of motor symptoms was significantly longer in these patients than in those who experienced constipation after onset of motor symptoms.

Conclusion

Constipation is a highly prevalent non-motor symptom in MSA and more often occurs before the onset of motor symptoms. The results of this study may help guide future research into MSA pathogenesis in its earliest stages.

When the microbiome helps the brain-current evidence

The gut microbiota-brain axis has been recognized as a network of connections that provides communication between the gut microflora and both central and autonomic nervous system. The gut microbiota alteration has been targeted for therapy in various neurodegenerative and psychiatric disbalances. Psychobiotics are probiotics that contribute beneficially to the brain function and the host mental health as a result of an interaction with the commensal gut bacteria, although their mechanism of action has not been completely revealed. In this state-of-art review, the findings about the potential therapeutic effects of the psychobiotics alone or in combination with conventional medicine in the treatment of neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease, as well as in some psychiatric diseases like depression, schizophrenia, and bipolar disorder, have been summarized. The evidence of the psychobiotics therapeutic outcomes obtained in preclinical and clinical trials have been given respectively for the observed neurodegenerative and psychiatric disorders.

Neurodegenerative and Neurodevelopmental Diseases and the Gut-Brain Axis: The Potential of Therapeutic Targeting of the Microbiome

The human gut microbiome contains the largest number of bacteria in the body and has the potential to greatly influence metabolism, not only locally but also systemically. There is an established link between a healthy, balanced, and diverse microbiome and overall health. When the gut microbiome becomes unbalanced (dysbiosis) through dietary changes, medication use, lifestyle choices, environmental factors, and ageing, this has a profound effect on our health and is linked to many diseases, including lifestyle diseases, metabolic diseases, inflammatory diseases, and neurological diseases. While this link in humans is largely an association of dysbiosis with disease, in animal models, a causative link can be demonstrated. The link between the gut and the brain is particularly important in maintaining brain health, with a strong association between dysbiosis in the gut and neurodegenerative and neurodevelopmental diseases. This link suggests not only that the gut microbiota composition can be used to make an early diagnosis of neurodegenerative and neurodevelopmental diseases but also that modifying the gut microbiome to influence the microbiome-gut-brain axis might present a therapeutic target for diseases that have proved intractable, with the aim of altering the trajectory of neurodegenerative and neurodevelopmental diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, autism spectrum disorder, and attention-deficit hyperactivity disorder, among others. There is also a microbiome-gut-brain link to other potentially reversible neurological diseases, such as migraine, post-operative cognitive dysfunction, and long COVID, which might be considered models of therapy for neurodegenerative disease. The role of traditional methods in altering the microbiome, as well as newer, more novel treatments such as faecal microbiome transplants and photobiomodulation, are discussed.

The role of the microbiota-gut-brain axis and intestinal microbiome dysregulation in Parkinson's disease

Parkinson's disease (PD) is a complex progressive neurodegenerative disease associated with aging. Its main pathological feature is the degeneration and loss of dopaminergic neurons related to the misfolding and aggregation of α-synuclein. The pathogenesis of PD has not yet been fully elucidated, and its occurrence and development process are closely related to the microbiota-gut-brain axis. Dysregulation of intestinal microbiota may promote the damage of the intestinal epithelial barrier, intestinal inflammation, and the upward diffusion of phosphorylated α-synuclein from the enteric nervous system (ENS) to the brain in susceptible individuals and further lead to gastrointestinal dysfunction, neuroinflammation, and neurodegeneration of the central nervous system (CNS) through the disordered microbiota-gut-brain axis. The present review aimed to summarize recent advancements in studies focusing on the role of the microbiota-gut-brain axis in the pathogenesis of PD, especially the mechanism of intestinal microbiome dysregulation, intestinal inflammation, and gastrointestinal dysfunction in PD. Maintaining or restoring homeostasis in the gut microenvironment by targeting the gut microbiome may provide future direction for the development of new biomarkers for early diagnosis of PD and therapeutic strategies to slow disease progression.

Gastrointestinal Dysfunction in Parkinson's Disease: Neuro-Gastroenterology Perspectives on a Multifaceted Problem

Patients with Parkinson's disease (PD) face a multitude of gastrointestinal (GI) symptoms, including nausea, bloating, reduced bowel movements, and difficulties with defecation. These symptoms are common and may accumulate during the course of PD but are often under-recognized and challenging to manage. Objective testing can be burdensome to patients and does not correlate well with symptoms. Effective treatment options are limited. Evidence is often based on studies in the general population, and specific evidence in PD is scarce. Upper GI dysfunction may also interfere with the pharmacological treatment of PD motor symptoms, which poses significant management challenges. Several new less invasive assessment tools and novel treatment options have emerged in recent years. The current review provides an overview and a practical approach to recognizing and diagnosing common upper and lower GI problems in PD, e.g., dyspepsia, gastroparesis, small bowel dysfunction, chronic constipation, and defecatory dysfunction. Management aspects are discussed based on the latest evidence from the PD and general populations, with insights for future research pertaining to GI dysfunction in PD.

The Gut Dysmotility Questionnaire for Parkinson's disease: Insights into development and pretest studies

Objective

A total of 48% of patients with Parkinson's disease (PD) present symptoms of gastrointestinal dysfunction, particularly constipation. Furthermore, gastrointestinal tract (GIT)-related non-motor symptoms (NMSs) appear at all stages of PD, can be prodromal by many years and have a relevant impact on the quality of life. There is a lack of GIT-focused validated tools specific to PD to assess their occurrence, progress, and response to treatment. The aim of this study was to develop and evaluate a novel, disease- and symptom-specific, self-completed questionnaire, titled Gut Dysmotility Questionnaire (GDQ), for screening and monitoring gastrointestinal dysmotility of the lower GIT in patients with PD.

Methods

In phase 1, a systematic literature review and multidisciplinary expert discussions were conducted. In phase 2, cognitive pretest studies comprising standard pretests, interviews, and evaluation questionnaires were performed in patients with PD (n = 21), age- and sex-matched healthy controls (HC) (n = 30), and neurologists (n = 11). Incorporating these results, a second round of cognitive pretests was performed investigating further patients with PD (n = 10), age- and sex-matched HC (n = 10), and neurologists (n = 5). The questionnaire was adapted resulting in the final GDQ, which underwent cross-cultural adaptation to the English language.

Results

We report significantly higher GDQ total scores and higher scores in five out of eight domains indicating a higher prevalence of gastrointestinal dysmotility in patients with PD than in HC (p &lt; 0.05). Cognitive pretesting improved the preliminary GDQ so that the final GDQ was rated as relevant (100/100%), comprehensive (100/90%), easy to understand concerning questions and answer options (100/90%), and of appropriate length (80/100%) by neurologists and patients with PD, respectively. The GDQ demonstrated excellent internal consistency (Cronbach‘s alpha value of 0.94). Evidence for good construct validity is given by moderate to high correlations of the GDQ total score and its domains by intercorrelations (rs = 0.67–0.91; p &lt; 0.001) and with validated general NMS measures as well as with specific items that assess gastrointestinal symptoms.

Interpretation

The GDQ is a novel, easy, and quick 18-item self-assessment questionnaire to screen for and monitor gastrointestinal dysmotility with a focus on constipation in patients with PD. It has shown high acceptance and efficacy as well as good construct validity in cognitive pretests.

Electroacupuncture for motor dysfunction and constipation in patients with Parkinson's disease: a randomised controlled multi-centre trial

BACKGROUND

Motor disturbances and non-motor disturbances such as constipation are the main factors affecting the quality of life in patients with Parkinson's disease (PD). We investigated the efficacy and safety of electroacupuncture combined with conventional pharmacological treatment on motor dysfunction and constipation in PD.

METHODS

In this multi-centre randomised controlled trial, we enrolled 166 eligible participants between September 19, 2018 and September 25, 2019 in four hospitals in China. Participants were randomly assigned (1:1) to the electroacupuncture (EA) group and the waitlist control group. Each participant in both groups received the conventional pharmacological treatment, EA group received 3 sessions of electroacupuncture per week for 12 weeks. The primary outcome was the change in the Unified Parkinson's Disease Rating Scale (UPDRS) score from baseline to week 12. The secondary outcomes included the evaluation of functional disability in motor symptoms and constipation, the adherence and adverse events were also recorded. Registered with Chictr.org.cn, ChiCTR1800019517.

FINDINGS

At week 12, the change in the UPDRS score of the EA group was significantly higher than that of the control group, with a difference of -9.1 points (95% CI, -11.8 to -6.4), and this difference continued into weeks 16 and 24. From baseline to week 12, the 39-item Parkinson Disease Question (PDQ-39) decreased by 10 points (interquartile range, IQR -26.0 to 0.0) in the EA group and 2.5 points (IQR: -11.0 to 4.0) in the control group, the difference was statistically significant. The time and steps for the 20-m walk at week 12, as well as the changes from baseline in the EA group, were comparable with that in the control group. But the EA group had a greater decrease than the control group from baseline in the times for 20-m walks at weeks 16 and 24. From week 4 to week 24, the median values of spontaneous bowel movements (SBMs) per week in the EA group were higher than that in the control group, the differences were all statistically significant. The incidence of EA-related adverse events during treatment was low, and they are mild and transient.

INTERPRETATION

The findings of our study suggested that compared with conventional pharmacological treatment, conventional pharmacological treatment combined with electroacupuncture significantly enhances motor function and increased bowel movements in patients with PD, electroacupuncture is a safe and effective treatment for PD.

FUNDING

Shanghai "Science and Technology Innovation Action Plan" Clinical Medicine Field Project (18401970700), Shanghai Special Project on Aging and Women's and Children's Health Research (020YJZX0134), Shanghai Clinical Research Centre for Acupuncture and Moxibustion (20MC1920500).

Sodium butyrate ameliorates gut dysfunction and motor deficits in a mouse model of Parkinson's disease by regulating gut microbiota

Background

A growing body of evidence showed that gut microbiota dysbiosis might be associated with the pathogenesis of Parkinson's disease (PD). Microbiota-targeted interventions could play a protective role in PD by regulating the gut microbiota-gut-brain axis. Sodium butyrate (NaB) could improve gut microbiota dysbiosis in PD and other neuropsychiatric disorders. However, the potential mechanism associated with the complex interaction between NaB and gut microbiota-gut-brain communication in PD needs further investigation.

Methods

C57BL/6 mice were subjected to a rotenone-induced PD model and were treated intragastrically with NaB for 4 weeks. The gut function and motor function were evaluated. The α-synuclein expression in colon and substantia nigra were detected by western blotting. Tyrosine hydroxylase (TH)-positive neurons in substantia nigra were measured by immunofluorescence. Moreover, gut microbiota composition was analyzed by 16S rRNA sequencing. Fecal short chain fatty acids (SCFAs) levels were determined by liquid chromatography tandem mass spectrometry (LC-MS). The levels of glucagon like peptide-1 (GLP-1) in tissues and serum were evaluated using enzyme-linked immunosorbent assay (ELISA).

Results

NaB ameliorated gut dysfunction and motor deficits in rotenone-induced mice. Meanwhile, NaB protected against rotenone-induced α-synuclein expression in colon and substantia nigra, and prevented the loss of TH-positive neurons. In addition, NaB could remodel gut microbiota composition, and regulate gut SCFAs metabolism, and restore GLP-1 levels in colon, serum, and substantia nigra in PD mice.

Conclusion

NaB could ameliorate gut dysfunction and motor deficits in rotenone-induced PD mice, and the mechanism might be associated with the regulation of gut microbiota dysbiosis.

Effects of a probiotic suspension Symprove™ on a rat early-stage Parkinson's disease model

An increasing number of studies in recent years have focused on the role that the gut may play in Parkinson's Disease (PD) pathogenesis, suggesting that the maintenance of a healthy gut may lead to potential treatments of the disease. The health of microbiota has been shown to be directly associated with parameters that play a potential role in PD including gut barrier integrity, immunity, function, metabolism and the correct functioning of the gut-brain axis. The gut microbiota (GM) may therefore be employed as valuable indicators for early diagnosis of PD and potential targets for preventing or treating PD symptoms. Preserving the gut homeostasis using probiotics may therefore lead to a promising treatment strategy due to their known benefits in improving constipation, motor impairments, inflammation, and neurodegeneration. However, the mechanisms underlying the effects of probiotics in PD are yet to be clarified. In this project, we have tested the efficacy of an oral probiotic suspension, Symprove™, on an established animal model of PD. Symprove™, unlike many commercially available probiotics, has been shown to be resistant to gastric acidity, improve symptoms in gastrointestinal diseases and improve gut integrity in an in vitro PD model. In this study, we used an early-stage PD rat model to determine the effect of Symprove™ on neurodegeneration and neuroinflammation in the brain and on plasma cytokine levels, GM composition and short chain fatty acid (SCFA) release. Symprove™ was shown to significantly influence both the gut and brain of the PD model. It preserved the gut integrity in the PD model, reduced plasma inflammatory markers and changed microbiota composition. The treatment also prevented the reduction in SCFAs and striatal inflammation and prevented tyrosine hydroxylase (TH)-positive cell loss by 17% compared to that observed in animals treated with placebo. We conclude that Symprove™ treatment may have a positive influence on the symptomology of early-stage PD with obvious implications for the improvement of gut integrity and possibly delaying/preventing the onset of neuroinflammation and neurodegeneration in human PD patients.

REM sleep behavior disorder correlates with constipation in de novo Chinese Parkinson's disease patients

BACKGROUND

Constipation, rapid eye movement sleep behavior disorder (RBD) and hyposmia are common prodromal symptoms of Parkinson's disease (PD), and they may represent two distinct types of disease origin, from the body or the brain. Our study aimed to compare the clinical characteristics of de novo PD patients with and without constipation and identify which prodromal symptoms were associated with constipation.

METHODS

A total of 111 de novo, drug-naïve Chinese PD patients were consecutively enrolled from Jan 2017 to Sept 2021. Patients were classified into PD with and without constipation based on item 5 of the Scales for Outcomes in Parkinson's disease-Autonomic Dysfunction (SCOPA-AUT). The demographic data, motor, and non-motor symptoms were compared between the two groups. The associated factors of constipation were analyzed by the multivariate logistic regression analysis.

RESULTS

In total, 44.1% (n = 49) of de novo PD patients had constipation. PD patients with constipation were older (p = 0.028), had higher proportions of Hoehn and Yahr (H-Y) stage [Formula: see text] 2 (p = 0.002), clinical possible RBD (cpRBD) (p = 0.002) and depression (p = 0.023), as well as marginal increase of hyposmia (p = 0.058) and freezing of gait (p = 0.069). After adjusting for H-Y stage and other confounding factors, cpRBD (OR = 3.508, p = 0.009), rather than hyposmia or depression, was closely related to constipation in de novo Chinese PD patients.

CONCLUSIONS

RBD is closely associated with constipation in de novo Chinese PD patients. Our results support the theory that prodromal symptoms that represent the same pathological origin are closely related to each other.

A postmortem study suggests a revision of the dual-hit hypothesis of Parkinson's disease

The dual-hit hypothesis of Parkinson's disease (PD) originally postulated that a neurotropic pathogen leads to formation of α-synuclein pathology in the olfactory bulb (OB) and dorsal motor nucleus of the vagus (DMV) and then invades the brain from these two entry points. Little work has been conducted to validate an important underlying premise for the dual-hit hypothesis, namely that the initial Lewy pathology does arise simultaneously in the OB and the enteric nervous system (ENS) plexuses and DMV at the earliest disease stage. We conducted a focused re-analysis of two postmortem datasets, which included large numbers of mild Lewy body disease (LBD) cases. We found that cases with α-synuclein pathology restricted to the peripheral autonomic nervous system and/or lower brainstem (early body-first LBD cases) very rarely had any OB pathology, suggesting that Lewy pathology commonly arises in the ENS without concomitant involvement of the OB. In contrast, cases with mild amygdala-predominant Lewy pathology (early brain-first LBD cases) nearly always showed OB pathology. This is compatible with the first pathology being triggered in the OB or amygdala followed by secondary spreading to connected structures, but without early involvement of the ENS or lower brainstem. These observations support that the pathologic process starts in either the olfactory bulb or the ENS, but rarely in the olfactory bulb and gut simultaneously. More studies on neuropathological datasets are warranted to reproduce these findings. The agreement between the revised single-hit hypothesis and the recently proposed brain-first vs. body-first model of LBD is discussed.

Fecal microbiome alterations in treatment-naive de novo Parkinson's disease

Gut microbiota alterations in Parkinson's disease (PD) have been found in several studies and are suggested to contribute to the pathogenesis of PD. However, previous results could not be adequately adjusted for a potential confounding effect of PD medication and disease duration, as almost all PD participants were already using dopaminergic medication and were included several years after diagnosis. Here, the gut microbiome composition of treatment-naive de novo PD subjects was assessed compared to healthy controls (HC) in two large independent case-control cohorts (n = 136 and 56 PD, n = 85 and 87 HC), using 16S-sequencing of fecal samples. Relevant variables such as technical batches, diet and constipation were assessed for their potential effects. Overall gut microbiome composition differed between PD and HC in both cohorts, suggesting gut microbiome alterations are already present in de novo PD subjects at the time of diagnosis, without the possible confounding effect of dopaminergic medication. Although no differentially abundant taxon could be replicated in both cohorts, multiple short chain fatty acids (SCFA) producing taxa were decreased in PD in both cohorts. In particular, several taxa belonging to the family Lachnospiraceae were decreased in abundance. Fewer taxonomic differences were found compared to previous studies, indicating smaller effect sizes in de novo PD.

Probiotics for constipation and gut microbiota in Parkinson's disease

INTRODUCTION

Constipation is one of the common non-motor symptoms in Parkinson's disease that significantly impacts patient quality of life. Probiotics supplementation may improve constipation symptoms, but its effect on the gut microbiota population is unclear.

METHODS

In this randomized controlled study, 46 PD patients with constipation according to Rome Ⅲ criteria were recruited. The number of complete bowel movements per week, degree of defecation effort, Bristol stool Scale (BSS), Patient Assessment of Constipation symptom (PAC-SYM) and Patient assessment of constipation quality of life questionnaire (PAC-QOL) were collected pre- and post-intervention to evaluate the constipation symptoms. In addition, fresh feces of subjects before and after intervention and healthy controls were collected for 16s rRNA gene V3-V4 region sequencing to compare bacterial flora differences.

RESULTS

Compared with the control group, the treatment group increased the average number of complete bowel movements per week (1.09 ± 1.24 vs. 0.04 ± 0.64, P < 0.001). Probiotics supplementation reduced the BSS score (0.65 ± 0.93 vs. -0.17 ± 0.94, P = 0.004), PAC-SYM score (4.09 ± 6.31 vs. -1.83 ± 4.14, P < 0.001), PAC-QOL score (10.65 ± 16.53 vs. 0.57 ± 12.82, P = 0.042), and degree of defecation effort score (1.00 ± 0.80 vs. 0.00 ± 0.30, P < 0.001). The improvement rate of constipation in the probiotics group was significantly higher than that in the control group (52.2% vs. 8.7%, P = 0.001). PD patients showed intestinal flora disorders compared to healthy controls. After 12 weeks of probiotics treatment, g_Christensenella_sp._Marseille-P2437 significantly increased, while g_Eubacterium_oxidoreducens_group, g_Eubacterium_hallii_group and s_Odoribacter_sp._N54.MGS-14 decreased (p < 0 0.05).

CONCLUSIONS

Probiotics treatment can effectively improve the constipation symptoms of PD patients and positively affected the gut microbiota.

Intestinal microbiota and neuroinflammation in Parkinson's disease: At the helm of the gut-brain axis

Emerging data suggest that disrupted intestinal microbiota, or dysbiosis, may be responsible for multiple features of Parkinson's disease (PD), from initiation, to progression, to therapeutic response. We have progressed greatly in our understanding of microbial signatures associated with PD, and have gained important insights into how dysbiosis and intestinal permeability promote neurodegeneration through neuroinflammation and Lewy body formation. These insights underscore the potential of microbiota-directed therapies, which include dietary, pharmacologic, and lifestyle interventions.

Gut microenvironmental changes as a potential trigger in Parkinson's disease through the gut-brain axis

Parkinson's disease (PD) is the second most common neurodegenerative disease attributed to the synergistic effects of genetic risk and environmental stimuli. Although PD is characterized by motor dysfunction resulting from intraneuronal alpha-synuclein accumulations, termed Lewy bodies, and dopaminergic neuronal degeneration in the substantia nigra, multiple systems are involved in the disease process, resulting in heterogenous clinical presentation and progression. Genetic predisposition to PD regarding aberrant immune responses, abnormal protein aggregation, autophagolysosomal impairment, and mitochondrial dysfunction leads to vulnerable neurons that are sensitive to environmental triggers and, together, result in neuronal degeneration. Neuropathology studies have shown that, at least in some patients, Lewy bodies start from the enteric nervous system and then spread to the central dopaminergic neurons through the gut-brain axis, suggesting the contribution of an altered gut microenvironment in the pathogenesis of PD. A plethora of evidence has revealed different gut microbiomes and gut metabolites in patients with PD compared to unaffected controls. Chronic gut inflammation and impaired intestinal barrier integrity have been observed in human PD patients and mouse models of PD. These observations led to the hypothesis that an altered gut microenvironment is a potential trigger of the PD process in a genetically susceptible host. In this review, we will discuss the complex interplay between genetic factors and gut microenvironmental changes contributing to PD pathogenesis.

Intestinal Transit in Early Moderate Parkinson’s Disease Correlates with Probable RBD: Subclinical Esophageal Dysmotility Does Not Correlate

Background

Nonmotor symptoms, including constipation and dysphagia, are very common in Parkinson's disease (PD) and Lewy pathology is widespread in the gastrointestinal tract, particularly in the lower esophagus. Constipation and REM sleep behavior disorder (RBD) may present prior to clinical diagnosis. Yet, little is known about esophageal dysfunction and its connection to constipation in early PD.

Objective

This study aimed to investigate esophageal and colonic transit in early moderate PD and to study correlations between symptoms and objective measures.

Methods

Thirty early moderate PD patients and 28 healthy controls (HC) were included in this cross-sectional study. Esophageal transit times were determined by esophageal scintigraphy and colonic transit times by CT after radio-opaque marker ingestion. Olfaction tests, clinical evaluation, and nonmotor questionnaires were also performed.

Results

Distal esophageal transit times and colonic transit times were both significantly prolonged in the PD group compared to HC (p < 0.05 andp < 0.01, respectively) and a moderate-strong positive correlation was found between colonic transit time (CTT) and RBDSQ score (r = 0.61,p < 0.001). Significant correlations were also found between CTT and SCOPA-AUT scores as well as between CTT and ROME III functional constipation scores.

Conclusion

Colonic transit correlates with probable RBD and is more severely prolonged in early moderate PD than is the distal esophageal transit time.

A 10-Year Bibliometric Analysis of Global Research on Gut Microbiota and Parkinson's Disease: Characteristics, Impact, and Trends

Objective

To perform a bibliometric analysis of scientific production related to gut microbiota and Parkinson's disease between 2011 and 2020.

Methods

A descriptive, retrospective, cross-sectional, and bibliometric study was carried out. The Scopus database was used as a source to evaluate the worldwide scientific production on intestinal microbiota and its relationship with Parkinson's disease. Data were extracted from Scopus using a formula developed with thesaurus terms MeSH (Medline) and Emtree (Embase).

Results

A total of 591 documents were found. The retrieved manuscripts received an average of 41.9 citations per document. Four of the 10 most productive authors were Italian. The University of Helsinki (Finland) was the institution with the highest scientific production (19 papers) and the highest impact (5921 citations). In terms of productivity and impact, Movement Disorders ranked first with 38 papers and 2782 citations, and those papers published in Q1 quartile journals exceeded the sum of the remaining quartiles. Papers with international collaboration were the most cited. Keyword analysis showed that the terms Parkinson Disease, Disease, and Intestine Flora were the most frequent.

Conclusion

The number of papers on Parkinson's disease and gut microbiota has been increasing; however, high-quality journals maintain the same high publication rate. International collaboration from high-income countries played an important role in the impact generated by the publications.

The Pathological Mechanism Between the Intestine and Brain in the Early Stage of Parkinson's Disease

Parkinson's disease (PD) is the second most common chronic progressive neurodegenerative disease. The main pathological features are progressive degeneration of neurons and abnormal accumulation of α-synuclein. At present, the pathogenesis of PD is not completely clear, and many changes in the intestinal tract may be the early pathogenic factors of PD. These changes affect the central nervous system (CNS) through both nervous and humoral pathways. α-Synuclein deposited in the intestinal nerve migrates upward along the vagus nerve to the brain. Inflammation and immune regulation mediated by intestinal immune cells may be involved, affecting the CNS through local blood circulation. In addition, microorganisms and their metabolites may also affect the progression of PD. Therefore, paying attention to the multiple changes in the intestinal tract may provide new insight for the early diagnosis and treatment of PD.

Practical pearls to improve the efficacy and tolerability of levodopa in Parkinson's disease

INTRODUCTION

Levodopa is the most effective medication for the treatment of motor symptoms of Parkinson's disease (PD). Several factors may affect the efficacy and tolerability of levodopa. These include the timing, dosage and administration of levodopa, concomitant drugs, food, PD-associated non motor symptoms, and various neurologic and non-neurologic comorbidities. If not appropriately addressed, these issues may limit levodopa efficacy, tolerability, and compliance.

AREAS COVERED

This article reviews the basics of the metabolism of orally administered levodopa, its side effects, and the factors that may affect its tolerability and efficacy. We provide several practical pearls to improve the tolerability and efficacy of levodopa.

EXPERT OPINION

Protein-rich food delays and reduces levodopa absorption. Hence, levodopa should preferably be administered in a relatively empty stomach. Carbidopa dosing is crucial as it not only enhances the entry of levodopa into the central nervous system, but also reduces levodopa's peripheral adverse effects. Patients experiencing the early side effects such as nausea/vomiting should be prescribed with anti-nausea medications that do not block dopamine receptors. Non-oral routes of administration can be used to obviate persistent gastrointestinal side effects. Implementation of these and other tips may help improve the tolerability and efficacy of levodopa.

Parkinson's Disease Is Associated with Impaired Gut-Blood Barrier for Short-Chain Fatty Acids

BACKGROUND

Short-chain fatty acids (SCFAs) produced by gut microbiota are reduced in feces but paradoxically increased in plasma of patients with Parkinson's disease (PD), which may stem from intestinal wall leakage. Gut function should be taken into consideration when conducting microbial-metabolite research.

OBJECTIVE

The objective was to investigate synchronous changes of SCFAs in feces and plasma of patients with PD, taking constipation as a confounder to better disentangle the SCFA metabolism exclusively associated with PD.

METHODS

The concentrations of fecal and plasma SCFAs in 33 healthy control subjects and 95 patients with PD were measured using liquid and gas chromatography mass spectrometry, respectively. Patients with PD were divided into patients with PD without constipation (n = 35) and patients with PD with constipation (n = 60). Gut-blood barrier (GBB) permeability was assessed by plasma/fecal ratio of SCFA concentrations and fecal α1-antitrypsin concentration.

RESULTS

Patients with PD displayed decreased concentrations of fecal acetic, propionic, and butyric acid and increased concentrations of plasma acetic and propionic acid. Fecal acetic, isobutyric, and isovaleric acid were lower and plasma acetic and propionic acid were higher in patients with PD with constipation than in patients with PD without constipation. Constipation aggravated GBB permeability in patients with PD. Combined fecal and plasma SCFAs could discriminate patients with PD from healthy control subjects. Fecal SCFAs, except propionic acid, were negatively correlated with disease severity, while plasma acetic, propionic, and valeric acid showed a positive correlation.

CONCLUSIONS

Our study showed alterations of fecal and plasma SCFAs in patients with PD that were associated with an impaired GBB and might be aggravated by constipation. © 2022 International Parkinson and Movement Disorder Society.

Movement Disorders and the Gut: A Review

There is a close link between multiple movement disorders and gastrointestinal dysfunction. Gastrointestinal symptoms may precede the development of the neurologic syndrome or may arise following the neurologic presentation. This review will provide an overview of gastrointestinal accompaniments to several well-known as well as lesser known movement disorders. It will also highlight several disorders which may not be considered primary movement disorders but have an overlapping presentation of both gastrointestinal and movement abnormalities.

Constipation Predicts Cognitive Decline in Parkinson's Disease: Results from the COPPADIS Cohort at 2-Year Follow-up and Comparison with a Control Group

BACKGROUND

Constipation has been linked to cognitive impairment development in Parkinson's disease (PD).

OBJECTIVE

Our aim was to analyze cognitive changes observed in PD patients and controls from a Spanish cohort with regards to the presence or not of constipation.

METHODS

PD patients and controls recruited from 35 centers of Spain from the COPPADIS cohort from January 2016 to November 2017 were followed-up during 2 years. The change in cognitive status from baseline (V0) to 2-year follow-up was assessed with the PD-CRS (Parkinson's Disease Cognitive Rating Scale). Subjects with a score ≥1 on item 21 of the NMSS (Non-Motor Symptoms Scale) at baseline (V0) were considered as "with constipation". Regression analyses were applied for determining the contribution of constipation in cognitive changes.

RESULTS

At V0, 39.7% (198/499) of PD patients presented constipation compared to 11.4% of controls (14/123) (p < 0.0001). No change was observed in cognitive status (PD-CRS total score) neither in controls without constipation (from 100.24±13.72 to 100.27±13.68; p = 0.971) and with constipation (from 94.71±10.96 to 93.93±13.03; p = 0.615). The PD-CRS total score decreased significantly in PD patients with constipation (from 89.14±15.36 to 85.97±18.09; p < 0.0001; Coehn's effect = -0.35) compared to patients without constipation (from 93.92±15.58 to 93.14±17.52; p = 0.250) (p = 0.018). In PD patients, to suffer from constipation at V0 was associated with a decrease in the PD-CRS total score from V0 to V2 (β= -0.1; 95% CI, -4.36 - -0.27; p = 0.026) and having cognitive impairment at V2 (OR = 1.79; 95% CI, 1.01 - 3.17; p = 0.045).

CONCLUSION

Constipation is associated with cognitive decline in PD patients but not in controls.

Importance of blinding and expectations in opioid-induced constipation: evidence from a randomized controlled trial

OBJECTIVES

Previous studies have found little association between objective measures and the subjective experience of opioid-induced constipation. The subjective experience of opioid-induced constipation may be influenced by treatment expectations. While most trials control for treatment expectations through blinding, success rate is generally low. This study aimed to explore the association between objective measures and the subjective experience of opioid-induced constipation, while considering blinding success and treatment expectations, and other psychological factors.

METHODS

Data from a randomized, double-blinded, placebo-controlled crossover trial including 21 healthy male participants was analyzed. Participants received either placebo, tapentadol, or oxycodone (in equipotent doses) for 14 days. They were assessed on objective and subjective measures of opioid-induced constipation (gastrointestinal transit time and the Patient Assessment of Constipation-Symptoms questionnaire, respectively), treatment guesses to indicate blinding success, and psychological factors.

RESULTS

There was a strong association between objective and subjective measures of opioid-induced constipation when participants were treated with oxycodone (r=0.676, p=0.006). Furthermore, participants were able to guess that they received active treatment when treated with oxycodone (p<0.001), suggesting that treatment expectations may have influenced the subjective experience of symptoms. Finally, patterns of moderate associations between opioid-induced constipation and other psychological factors emerged, although none reached significance (p>0.05).

CONCLUSIONS

Results indicate that treatment expectations could play an important role in the subjective experience of opioid-induced constipation, and support the importance of assessing blinding success in study trials. Besides expectations, other psychological factors may be associated with opioid-induced constipation.

To the Gut Microbiome and Beyond: The Brain-First or Body-First Hypothesis in Parkinson's Disease

There is continued debate regarding Parkinson’s disease etiology and whether it originates in the brain or begins in the gut. Recently, evidence has been provided for both, with Parkinson’s disease onset presenting as either a “body-first” or “brain-first” progression. Most research indicates those with Parkinson’s disease have an altered gut microbiome compared to controls. However, some studies do not report gut microbiome differences, potentially due to the brain or body-first progression type. Based on the etiology of each proposed progression, individuals with the body-first progression may exhibit altered gut microbiomes, i.e., where short-chain fatty acid producing bacteria are reduced, while the brain-first progression may not. Future microbiome research should consider this hypothesis and investigate whether gut microbiome differences exist between each type of progression. This may further elucidate the impact of the gut microbiome in Parkinson’s disease and show how it may not be homogenous across individuals with Parkinson’s disease.

Gastrointestinal involvement in Parkinson's disease: pathophysiology, diagnosis, and management

Growing evidence suggests an increasing significance for the extent of gastrointestinal tract (GIT) dysfunction in Parkinson's disease (PD). Most patients suffer from GIT symptoms, including dysphagia, sialorrhea, bloating, nausea, vomiting, gastroparesis, and constipation during the disease course. The underlying pathomechanisms of this α-synucleinopathy play an important role in disease development and progression, i.e., early accumulation of Lewy pathology in the enteric and central nervous systems is implicated in pharyngeal discoordination, esophageal and gastric motility/peristalsis impairment, chronic pain, altered intestinal permeability and autonomic dysfunction of the colon, with subsequent constipation. Severe complications, including malnutrition, dehydration, insufficient drug effects, aspiration pneumonia, intestinal obstruction, and megacolon, frequently result in hospitalization. Sophisticated diagnostic tools are now available that permit more detailed examination of specific GIT impairment patterns. Furthermore, novel treatment approaches have been evaluated, although high-level evidence trials are often missing. Finally, the burgeoning literature devoted to the GIT microbiome reveals its importance for neurologists. We review current knowledge about GIT pathoanatomy, pathophysiology, diagnosis, and treatment in PD and provide recommendations for management in daily practice.

Dysautonomia in Parkinson’s Disease: Impact of Glucocerebrosidase Gene Mutations on Cardiovascular Autonomic Control

Evidence from clinical practice suggests that PD patients with the Glucocerebrosidase gene mutations (GBA-PD) are characterized by more severe dysautonomic symptoms than patients with idiopathic PD (iPD). Therefore, an accurate assessment of cardiovascular autonomic control (CAC) is necessary to clarify the role of GBA mutations in the pathophysiology of PD. We evaluated the CAC at rest and during orthostatic challenge of 15 iPD, 15 GBA-PD and 15 healthy controls (CTR). ECG and respiration were recorded in supine position and during active standing. The analysis of Heart Rate Variability (HRV) was performed on ECG recordings using two different approaches, linear spectral analysis and non-linear symbolic analysis. GBA-PD patients presented more frequently an akinetic-rigid phenotype and cognitive dysfunction than iPD patients. Both iPD and GBA-PD group were characterized by a lower spectral HRV than CTR group. At rest, the GBA-PD group was characterized by a lower parasympathetic modulation and a shift of the sympathovagal balance toward a sympathetic predominance compared to the CTR group. Moreover, the GBA-PD patients presented a lower HR increment and a lower or absent reduction of the vagal modulation in response to the active standing than iPD patients. Lastly, the cardiovascular autonomic dysfunction in PD patients was associated with longer disease duration, and with the occurrence of REM sleep behavior disorder and constipation. Our findings suggest a more severe impairment of the CAC in PD patients with GBA mutations. These results and further studies on the role of GBA mutations could allow a stratification based on cardiovascular risk in PD patients and the implementation of specific prevention programs.

Gastrointestinal Dysfunction in Parkinson’s Disease: Current and Potential Therapeutics

Abnormalities in the gastrointestinal (GI) tract of Parkinson’s disease (PD) sufferers were first reported over 200 years ago; however, the extent and role of GI dysfunction in PD disease progression is still unknown. GI dysfunctions, including dysphagia, gastroparesis, and constipation, are amongst the most prevalent non-motor symptoms in PD. These symptoms not only impact patient quality of life, but also complicate disease management. Conventional treatment pathways for GI dysfunctions (i.e., constipation), such as increasing fibre and fluid intake, and the use of over-the-counter laxatives, are generally ineffective in PD patients, and approved compounds such as guanylate cyclase C agonists and selective 5-hyroxytryptamine 4 receptor agonists have demonstrated limited efficacy. Thus, identification of potential targets for novel therapies to alleviate PD-induced GI dysfunctions are essential to improve clinical outcomes and quality of life in people with PD. Unlike the central nervous system (CNS), where PD pathology and the mechanisms involved in CNS damage are relatively well characterised, the effect of PD at the cellular and tissue level in the enteric nervous system (ENS) remains unclear, making it difficult to alleviate or reverse GI symptoms. However, the resurgence of interest in understanding how the GI tract is involved in various disease states, such as PD, has resulted in the identification of novel therapeutic avenues. This review focuses on common PD-related GI symptoms, and summarizes the current treatments available and their limitations. We propose that by targeting the intestinal barrier, ENS, and/or the gut microbiome, may prove successful in alleviating PD-related GI symptoms, and discuss emerging therapies and potential drugs that could be repurposed to target these areas.

New approaches to treatments for sleep, pain and autonomic failure in Parkinson's disease - Pharmacological therapies

Non-motor symptoms (NMSs) are highly prevalent throughout the course of Parkinson's disease (PD). Pain, autonomic dysfunction and sleep disturbances remain at the forefront of the most common NMSs; their treatment is challenging and their effect on the quality of life of both patients and caregivers detrimental. Yet, the landscape of clinical trials in PD is still dominated by therapeutic strategies seeking to ameliorate motor symptoms; subsequently, effective strategies to successfully treat NMSs remain a huge unmet need. Wider awareness among industry and researchers is thus essential to give rise to development and delivery of high-quality, large-scale clinical trials in enriched populations of patients with PD-related pain, autonomic dysfunction and sleep. In this review, we discuss recent developments in the field of pharmacological treatment strategies designed or re-purposed to target three key NMSs: pain, autonomic dysfunction and sleep disturbances. We focus on emerging evidence from recent clinical trials and outline some exciting and intriguing findings that call for further investigations.

Lower GDNF Serum Level Is a Possible Risk Factor for Constipation in Patients With Parkinson Disease: A Case–Control Study

Background: Constipation is a significant symptom of Parkinson's disease (PD). Glial-derived neurotrophic factor (GDNF) is important for the morphogenesis of the enteric nervous system and plays a critical role in the preservation of mucosal integrity under enteric glia surveillance. The aim of this work was to evaluate the serum levels of GDNF in patients with PD with and without constipation.

Methods: This work included 128 patients with PD. The patients were classified into three groups: those with PD but no constipation (nCons-PD) (n = 49), those with prodromal stage constipation (Cons-Pro-PD) (n = 48), and those with clinical stage constipation (Cons-Clinic-PD) (n = 31). The association between serum GDNF concentration and constipation was explored using logical regression.

Results: The nCons-PD group's mean GDNF levels were 528.44 pg/ml, which was higher than the Cons-Pro-PD group's 360.72 pg/ml and the Cons-Clinic-PD group's 331.36 pg/ml. The results of binary logistic regression indicated that GDNF was a protective factor in the prevention of constipation. Cons-Clinic-PD group had a higher score of MDS-UPDRS-II, MDS-UPDRS-III, MDS-UPDRS-IV, and a higher H-Y staging as compared with nCons-PD group. Relative to the nCons-PD group, Cons-Clinic-PD had higher NMSS scores, lower MoCA and PDSS scores, and were more likely to have RBD.

Conclusions: GDNF serum levels are lower in patients with PD who are constipated. A low GDNF level is a potential risk factor for constipation in patients with PD.

Clinical and imaging evidence of brain-first and body-first Parkinson's disease

Braak's hypothesis has been extremely influential over the last two decades. However, neuropathological and clinical evidence suggest that the model does not conform to all patients with Parkinson's disease (PD). To resolve this controversy, a new model was recently proposed; in brain-first PD, the initial α-synuclein pathology arise inside the central nervous system, likely rostral to the substantia nigra pars compacta, and spread via interconnected structures - eventually affecting the autonomic nervous system; in body-first PD, the initial pathological α-synuclein originates in the enteric nervous system with subsequent caudo-rostral propagation to the autonomic and central nervous system. By using REM-sleep behavior disorder (RBD) as a clinical identifier to distinguish between body-first PD (RBD-positive at motor symptom onset) and brain-first PD (RBD-negative at motor symptom onset), we explored the literature to evaluate clinical and imaging differences between these proposed subtypes. Body-first PD patients display: 1) a larger burden of autonomic symptoms - in particular orthostatic hypotension and constipation, 2) more frequent pathological α-synuclein in peripheral tissues, 3) more brainstem and autonomic nervous system involvement in imaging studies, 4) more symmetric striatal dopaminergic loss and motor symptoms, and 5) slightly more olfactory dysfunction. In contrast, only minor cortical metabolic alterations emerge before motor symptoms in body-first. Brain-first PD is characterized by the opposite clinical and imaging patterns. Patients with pathological LRRK2 genetic variants mostly resemble a brain-first PD profile whereas patients with GBA variants typically conform to a body-first profile. SNCA-variant carriers are equally distributed between both subtypes. Overall, the literature indicates that body-first and brain-first PD might be two distinguishable entities on some clinical and imaging markers.

Enhanced Contractive Tension and Upregulated Muscarinic Receptor 2/3 in Colorectum Contribute to Constipation in 6-Hydroxydopamine-Induced Parkinson's Disease Rats

Constipation and defecatory dysfunctions are frequent symptoms in patients with Parkinson’s disease (PD). The pathology of Lewy bodies in colonic and rectal cholinergic neurons suggests that cholinergic pathways are involved in colorectal dysmotility in PD. However, the underlying mechanism is unclear. The aim of the present study is to examine the effect of central dopaminergic denervation in rats, induced by injection 6-hydroxydopamine into the bilateral substania nigra (6-OHDA rats), on colorectal contractive activity, content of acetylcholine (ACh), vasoactive intestinal peptide (VIP) and expression of neural nitric oxide synthase (nNOS) and muscarinic receptor (MR). Strain gauge force transducers combined with electrical field stimulation (EFS), gut transit time, immunohistochemistry, ELISA, western blot and ultraperformance liquid chromatography tandem mass spectrometry were used in this study. The 6-OHDA rats exhibited outlet obstruction constipation characterized by prolonged transit time, enhanced contractive tension and fecal retention in colorectum. Pretreatment with tetrodotoxin significantly increased the colorectal motility. EFS-induced cholinergic contractions were diminished in the colorectum. Bethanechol chloride promoted colorectal motility in a dose-dependent manner, and much stronger reactivity of bethanechol chloride was observed in 6-OHDA rats. The ACh, VIP and protein expression of nNOS was decreased, but M₂R and M₃R were notably upregulated in colorectal muscularis externa. Moreover, the number of cholinergic neurons was reduced in sacral parasympathetic nucleus (SPN) of 6-OHDA rats. In conclusion, central nigrostriatal dopaminergic denervation is associated with decreased cholinergic neurons in SPN, decreased ACh, VIP content, and nNOS expression and upregulated M₂R and M₃R in colorectum, resulting in colorectal dysmotility, which contributes to outlet obstruction constipation. The study provides new insights into the mechanism of constipation and potential therapeutic targets for constipation in PD patients.