Constipation Increases Disability and Decreases Dopamine Levels in the Nigrostriatal System through Gastric Inflammatory Factors in Parkinson's Disease

Constipation is associated with emotional and cognitive impairment in patients with Parkinson's disease: A clinical and brain functional study

OBJECTIVE

Constipation frequently occurs in patients with Parkinson's disease (PD) and may be related to cognitive and emotional disorders. The aim of this study is to investigate the clinical and brain functional characteristics of patients with PD presenting with constipation.

METHODS

The motor and non-motor symptoms of patients with PD were evaluated, and a resting-state functional magnetic resonance imaging (RS-fMRI) study was conducted based on propensity score matching. Alterations in brain function were analyzed using regional homogeneity (ReHo) and functional connectivity (FC).

RESULTS

Compared with patients without constipation (PD-NC group), patients with constipation (PD-C group) had more serious motor and non-motor symptoms (including cognitive and emotional disorders along with visual hallucinations). Further, emotional and cognitive disorders were correlated with the occurrence of constipation in patients with PD. Compared with the PD-NC group, the PD-C group showed a reduced ReHo of the right insula and bilateral orbitofrontal cortex (OFC), increased ReHo of the left postcentral gyrus, and enhanced FC between the right OFC and the left middle temporal gyrus (MTG) and middle occipital gyrus (MOG). Additionally, the activity of the OFC and insula was significantly correlated with the constipation, mood, and cognitive levels of patients with PD.

CONCLUSIONS

Constipation in patients with PD is closely related to emotional and cognitive impairments, abnormal activity and FC of brain regions such as the right insula and bilateral OFC may play an important role in this.

PET brain imaging in neurological disorders

Brain disorders are a series of conditions with damage or loss of neurons, such as Parkinson's disease (PD), Alzheimer's disease (AD), or drug dependence. These individuals have gradual deterioration of cognitive, motor, and other central nervous system functions affected. This degenerative trajectory is intricately associated with dysregulations in neurotransmitter systems. Positron Emission Tomography (PET) imaging, employing radiopharmaceuticals and molecular imaging techniques, emerges as a crucial tool for detecting brain biomarkers. It offers invaluable insights for early diagnosis and distinguishing brain disorders. This article comprehensively reviews the application and progress of conventional and novel PET imaging agents in diagnosing brain disorders. Furthermore, it conducts a thorough analysis on merits and limitations. The article also provides a forward-looking perspective in the future development directions of PET imaging agents for diagnosing brain disorders and proposes potential innovative strategies. It aims to furnish clinicians and researchers with an all-encompassing overview of the latest advancements and forthcoming trends in the utilization of PET imaging for diagnosing brain disorders.

Interactions between gut microbiota and Parkinson's disease: The role of microbiota-derived amino acid metabolism

Non-motor symptoms (NMS) of Parkinson's disease (PD), such as constipation, sleep disorders, and olfactory deficits, may emerge up to 20 years earlier than motor symptoms. A series of evidence indicates that the pathology of PD may occur from the gastrointestinal tract to the brain. Numerous studies support that the gut microbiota communicates with the brain through the immune system, special amino acid metabolism, and the nervous system in PD. Recently, there is growing recognition that the gut microbiota plays a vital role in the modulation of multiple neurochemical pathways via the “gut microbiota-brain axis” (GMBA). Many gut microbiota metabolites, such as fatty acids, amino acids, and bile acids, convey signaling functions as they mediate the crosstalk between gut microbiota and host physiology. Amino acids' abundance and species alteration, including glutamate and tryptophan, may disturb the signaling transmission between nerve cells and disrupt the normal basal ganglia function in PD. Specific amino acids and their receptors are considered new potential targets for ameliorating PD. The present study aimed to systematically summarize all available evidence on the gut microbiota-derived amino acid metabolism alterations associated with PD.

Constipation is Associated with Development of Cognitive Impairment in de novo Parkinson's Disease: A Longitudinal Analysis of Two International Cohorts

BACKGROUND

Constipation is regarded as one of the prodromal features of Parkinson's disease (PD) and there is emerging evidence linking gastrointestinal dysfunction and cognitive impairment (CI) in PD.

OBJECTIVE

We explored whether constipation is associated with development of CI in two independent cohorts of de novo PD patients (n = 196 from the Non-motor International Longitudinal Study [NILS] and n = 423 from the Parkinson's Progression Markers Initiative [PPMI] study).

METHODS

Constipation was clinically defined using the Non-Motor Symptoms Scale (NMSS) item-21 [NILS] and Scales for Outcomes in PD-Autonomic (SCOPA-AUT) item-5 [PPMI]. We assessed baseline group differences (PD with or without constipation) in CI, global non-motor symptoms burden, motor dysfunction, and striatal dopaminergic denervation. Kaplan-Meier method estimated group differences in cumulative proportion of patients with incident CI over three years. In PPMI, we subsequently performed univariate and multivariate Cox survival analyses to evaluate whether constipation predicts incident mild cognitive impairment or dementia over a 6-year period, including constipation and other known predictors of CI as covariates.

RESULTS

Patients with constipation had greater motor and global non-motor burden in both cohorts at baseline (p < 0.05). Kaplan-Meier plots showed faster conversion to CI in patients with constipation in both cohorts (p < 0.05). In PPMI, 37 subjects developed dementia during a mean follow-up of 4.9 years, and constipation was an independent predictor of dementia onset (hazard ratio = 2.311; p = 0.02).

CONCLUSION

Constipation in de novo PD patients is associated with development of cognitive decline and may serve as a clinical biomarker for identification of patients at risk for cognitive impairment.

The Gastrointestinal Dysfunction Scale for Parkinson's Disease

BACKGROUND

Gastrointestinal dysfunction is an important feature of Parkinson's disease (PD), and there is increasing evidence that it may play a key role in the disease process. However, its assessment is limited by different tools and underlying differences in diagnostic criteria for gastrointestinal dysfunction. To date, there is no psychometric instrument for quantitative evaluation of gastrointestinal symptoms specifically designed for use in PD.

OBJECTIVE

The objective of this study was to develop a self-report questionnaire-based instrument, the Gastrointestinal Dysfunction Scale for Parkinson's Disease, and to evaluate its psychometric properties.

METHODS

We performed a literature review and conducted 3 focus groups to develop the Gastrointestinal Dysfunction Scale for Parkinson's Disease. Three hundred and sixteen patients with PD and 55 controls completed the Gastrointestinal Dysfunction Scale for Parkinson's Disease, the Non-Motor Symptom Scale, the Hospital Anxiety and Depression Scale, and a stool diary adapted from the Bristol Stool Chart.

RESULTS

The Gastrointestinal Dysfunction Scale for Parkinson's Disease demonstrated good internal consistency (Cronbach's α = 0.82) and test-retest stability (0.79 < ICCs > 0.94). Correlation analyses supported good convergent and divergent validity. Receiver operating characteristic analysis demonstrated that a cutoff score of ≥9 on the Gastrointestinal Dysfunction Scale for Parkinson's Disease Constipation subscale discriminates between PD patients with and without constipation.

CONCLUSIONS

The Gastrointestinal Dysfunction Scale for Parkinson's Disease is a novel disease-specific self-report tool to quantitatively assess the presence and severity of gastrointestinal dysfunction features in patients with PD, with strong reliability and validity. Further longitudinal studies are needed to demonstrate its utility in tracking gastrointestinal dysfunction in PD clinical cohorts. © 2021 International Parkinson and Movement Disorder Society.

Posture Instability Is Associated with Dopamine Drop of Nigrostriatal System and Hypometabolism of Cerebral Cortex in Parkinson Disease

BACKGROUND

Posture instability (PI) is known to be a severe complication in Parkinson's disease (PD), and its mechanism remains poorly understood. Our study aims to explore the changes of brain network in PI of PD, and further investigate the role of peripheral inflammation on activities of different brain regions in PD with PI.

METHODS

167 individuals were recruited, including 36 PD cases with PI and 131 ones without PI. We carefully assessed the status of motor and cognitive function, measured serum inflammatory factors, and detected the dopaminergic pathways and the metabolism of different brain regions by positron emission tomography (PET). Data analysis was conducted by variance, univariate analysis, chi-square analysis, logistic regression, and partial correlation.

RESULT

No difference was found for age or onset age between the two groups (P>0.05). Female patients were susceptible to posture impairment and had a 2.14-fold risk for PI compared with male patients in PD (P<0.05). Patients with PI had more severe impairment of motor and cognitive function for a longer duration than those without PI (P<0.05). The mean uptake ratios of presynaptic vesicular monoamine transporter (VMAT2), which were detected in the caudate nucleus and putamen, were lower in PI group than those without PI (P<0.05). There were lower activities of the midbrain, caudate nucleus, and anterior medial temporal cortex in PI group than those in the non-PI group (P<0.05). Although serum concentrations of immunoglobulins (IgG, IgM, and IgA) and complements (C3, C4) were higher in PI group than those in the non-PI group, only serum IgM concentration had a significant difference between the two groups (P<0.05). We further explored significant inverse correlations of IgG, IgM, IgA, and C4 with activities of some cerebral cortex in PI of PD (P<0.05).

CONCLUSION

Female patients were susceptible to posture instability and had a 2.14-fold risk for PI of PD. Patients with PI had more severe impairments of motor and cognitive function for a longer duration than those without PI. PI was associated with dopamine drop of the nigrostriatal system and lower activities of the limbic cortex in PD. Peripheral inflammation may be involved in degeneration of the cerebral cortex in PD combined with PI.

Early constipation predicts faster dementia onset in Parkinson's disease

Constipation is a common but not a universal feature in early PD, suggesting that gut involvement is heterogeneous and may be part of a distinct PD subtype with prognostic implications. We analysed data from the Parkinson's Incidence Cohorts Collaboration, composed of incident community-based cohorts of PD patients assessed longitudinally over 8 years. Constipation was assessed with the MDS-UPDRS constipation item or a comparable categorical scale. Primary PD outcomes of interest were dementia, postural instability and death. PD patients were stratified according to constipation severity at diagnosis: none (n = 313, 67.3%), minor (n = 97, 20.9%) and major (n = 55, 11.8%). Clinical progression to all three outcomes was more rapid in those with more severe constipation at baseline (Kaplan-Meier survival analysis). Cox regression analysis, adjusting for relevant confounders, confirmed a significant relationship between constipation severity and progression to dementia, but not postural instability or death. Early constipation may predict an accelerated progression of neurodegenerative pathology.

Protein Deimination Signatures in Plasma and Plasma-EVs and Protein Deimination in the Brain Vasculature in a Rat Model of Pre-Motor Parkinson's Disease

The identification of biomarkers for early diagnosis of Parkinson’s disease (PD) is of pivotal importance for improving approaches for clinical intervention. The use of translatable animal models of pre-motor PD therefore offers optimal opportunities for novel biomarker discovery in vivo. Peptidylarginine deiminases (PADs) are a family of calcium-activated enzymes that contribute to protein misfolding through post-translational deimination of arginine to citrulline. Furthermore, PADs are an active regulator of extracellular vesicle (EV) release. Both protein deimination and extracellular vesicles (EVs) are gaining increased attention in relation to neurodegenerative diseases, including in PD, while roles in pre-motor PD have yet to be investigated. The current study aimed at identifying protein candidates of deimination in plasma and plasma-EVs in a rat model of pre-motor PD, to assess putative contributions of such post-translational changes in the early stages of disease. EV-cargo was further assessed for deiminated proteins as well as three key micro-RNAs known to contribute to inflammation and hypoxia (miR21, miR155, and miR210) and also associated with PD. Overall, there was a significant increase in circulating plasma EVs in the PD model compared with sham animals and inflammatory and hypoxia related microRNAs were significantly increased in plasma-EVs of the pre-motor PD model. A significantly higher number of protein candidates were deiminated in the pre-motor PD model plasma and plasma-EVs, compared with those in the sham animals. KEGG (Kyoto encyclopedia of genes and genomes) pathways identified for deiminated proteins in the pre-motor PD model were linked to “Alzheimer’s disease”, “PD”, “Huntington’s disease”, “prion diseases”, as well as for “oxidative phosphorylation”, “thermogenesis”, “metabolic pathways”, “Staphylococcus aureus infection”, gap junction, “platelet activation”, “apelin signalling”, “retrograde endocannabinoid signalling”, “systemic lupus erythematosus”, and “non-alcoholic fatty liver disease”. Furthermore, PD brains showed significantly increased staining for total deiminated proteins in the brain vasculature in cortex and hippocampus, as well as increased immunodetection of deiminated histone H3 in dentate gyrus and cortex. Our findings identify EVs and post-translational protein deimination as novel biomarkers in early pre-motor stages of PD.

Peripheral Humoral Immune Response Is Associated With the Non-motor Symptoms of Parkinson's Disease

Background

Non-motor symptoms are common in Parkinson’s disease (PD) and can even be used as part of the supportive criteria for diagnosis. Chronic inflammation is involved in every stage of PD. Disorders of the immune system affect the peripheral blood. Whether the humoral immune response is associated with the non-motor symptoms of PD remains unknown.

Methods

Mann–Whitney tests and Bonferroni correction were used to compare the serum levels of IgG, IgA, IgM, C3, and C4 between 180 sporadic PD patients and 187 healthy controls. Multiple regression models were conducted to assess the associations among these indicators of humoral immunity and the clinical features of PD patients.

Results

Male PD patients had lower levels of C3 and C4 than healthy controls [0.87 (0.22) vs. 0.96 (0.19); 0.19 (0.06) vs. 0.22 (0.07), respectively, Pc < 0.01] and lower levels of C3 than female PD patients [0.87 (0.22) vs. 1.02 (0.23), Pc < 0.01]. Patients suffering from attention/memory problems had significantly lower levels of IgA and C3 than those without these problems [1.92 (1.21) vs. 2.57 (0.76); 0.89 (0.24) vs. 0.97 (0.24), respectively, Pc < 0.04]. In addition, serum IgG levels were negatively associated with mood/cognition problem scores and were positively associated with gastrointestinal tract problem scores (adjusted R² = 0.063, F = 1.805, p = 0.038). Serum C3 levels were negatively associated with being male, age, and sleep/fatigue problem scores (adjusted R² = 0.123, F = 2.678, p = 0.001).

Conclusion

The peripheral humoral immune response might be correlated with the non-motor symptoms of PD.