Association between irritable bowel syndrome and Parkinson's disease: A systematic review and meta-analysis

Association between irritable bowel syndrome and Parkinson's disease by Cohort study and Mendelian randomization analysis

This study aimed to investigate the association between irritable bowel syndrome (IBS) and Parkinson's disease (PD) utilizing prospective cohort study and Mendelian randomization. The dataset contained a substantial cohort of 426,911 participants from the UK Biobank, discussing the association between IBS and PD with Cox proportional hazards models and case-control analysis while adjusting for covariates such as age, gender, ethnicity and education level. In univariate Cox regression model, the risk of PD was reduced in IBS patients (HR: 0.774, 95%CI: 0.625-0.956, P = 0.017), but the statistical significance diminished in the three models after adjusting for other variables. In a few subgroup analyses, IBS patients are less likely to develop into PD, and patients diagnosed with IBS after 2000 also had a lower risk (HR: 0.633, 95%CI: 0.403-0.994, P = 0.047) of subsequently developing PD. In addition, we matched five healthy control participants based on gender and age at the end of the study for each IBS patient diagnosed during the follow-up period, and logistic regression results (OR:1.239, 95%CI: 0.896-1.680, P = 0.181) showed that IBS was not associated with the risk of PD. Mendelian randomization did not find significant evidence of the causal relationship between IBS and Parkinson's disease (OR: 0.801, 95%CI: 0.570-1.278, P = 0.204). Overall, we suggest that IBS status is not associated with the risk of developing PD, and that these findings provide valuable insights into the clinical management and resource allocation of patients with IBS.

"Sentinel or accomplice": gut microbiota and microglia crosstalk in disorders of gut-brain interaction

Abnormal brain-gut interaction is considered the core pathological mechanism behind the disorders of gut-brain interaction (DGBI), in which the intestinal microbiota plays an important role. Microglia are the "sentinels" of the central nervous system (CNS), which participate in tissue damage caused by traumatic brain injury, resist central infection and participate in neurogenesis, and are involved in the occurrence of various neurological diseases. With in-depth research on DGBI, we could find an interaction between the intestinal microbiota and microglia and that they are jointly involved in the occurrence of DGBI, especially in individuals with comorbidities of mental disorders, such as irritable bowel syndrome (IBS). This bidirectional regulation of microbiota and microglia provides a new direction for the treatment of DGBI. In this review, we focus on the role and underlying mechanism of the interaction between gut microbiota and microglia in DGBI, especially IBS, and the corresponding clinical application prospects and highlight its potential to treat DGBI in individuals with psychiatric comorbidities.

Irritable bowel syndrome based on Rome IV diagnostic criteria associates with non-motor symptoms of Parkinson's disease

BACKGROUND

Recent concepts suggest that the neuropathological hallmark of Parkinson's disease (PD) may in part originate from the enteric nervous system. We evaluated the frequency of functional gastrointestinal disorders in PD patients using Rome IV criteria and correlated the clinical severity of PD.

METHODS

PD patients and matched controls were recruited between January 2020 and December 2021. Rome IV criteria were used to diagnose constipation and irritable bowel syndrome (IBS). Severity of PD motor symptoms was evaluated using UPDRS part III scores and non-motor symptoms using Non-motor Symptoms Scale (NMSS).

RESULTS

A total of 99 PD patients and 64 controls were enrolled. The prevalence of constipation (65.7% vs. 34.3%, P < 0.001) and IBS (18.1% vs 5%, P = 0.02) were significantly higher in PD patients than controls. The prevalence of IBS was higher in early-stage PD than advanced-stage PD (14.43% vs. 8.25%, P = 0.02), whereas constipation was more common in advanced stages (71.43% vs. 18.56%, P < 0.001). PD patients with IBS had higher NMSS total scores (P < 0.01) than those without IBS. The severity of IBS correlated with NMSS scores (r = 0.71, P < 0.001), especially subscores in domain 3 assessing mood disorders (r = 0.83, P < 0.001), but not UPDRS part III scores (r = 0.06, P = 0.45). The severity of constipation correlated with the UPDRS part III scores (r = 0.59, P < 0.001) but not the domain 3 mood subscores (r = 0.15, P = 0.07).

CONCLUSION

The prevalence of IBS and constipation was higher in PD patients than controls and phenotypic correlation supported the occurrence of IBS with higher non-motor symptom burden, especially mood symptoms, in PD patients.

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.

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 Symptoms in Multiple System Atrophy Using Rome Criteria and Their Impact on Personalized Medicine

Constipation is one of the most common non-motor symptoms in multiple system atrophy (MSA); however, it has not been evaluated according to the standard diagnostic criteria for constipation in patients with MSA. We evaluated the characteristics of constipation in patients with MSA by using Rome criteria (Rome III), which has been validated and the widely used for gastrointestinal disorders. Fifty-one patients with MSA (29 female) were enrolled in the study. Based on the Rome III criteria, constipation was diagnosed in 29 patients (56.9%); irritable bowel syndrome was not detected. Thirty-seven patients (72.5%) were aware of their constipation. The most common constipation symptom was the sensation of anorectal obstruction (68.6%). Patients’ self-awareness of constipation was most strongly correlated to the sensation of incomplete evacuation (odds ratio: 7.377, 95% confidence interval: 1.402−38.817). The number of constipation-related symptoms was correlated with the total levodopa equivalent dose (p < 0.05). Rome criteria, which can detect various constipation symptoms, are useful for evaluating constipation in MSA, and these findings may greatly impact personalized medicine.