Evaluating the effectiveness of probiotics in relieving constipation in Parkinson’s disease: A systematic review and meta-analysis

OBJECTIVES: The aim of this study was to evaluate the effects of probiotics on the treatment of constipation in patients with Parkinson’s disease (PD) by analyzing data from published randomized clinical trials (RCTs). PD is a neurodegenerative disease characterized by clinical symptoms such as rigidity, bradykinesia, and resting tremor. Constipation is a common complaint reported by PD patients. Probiotics are often used to treat functional constipation. The potential mechanisms behind PD-related constipation include dysfunction of the enteric nervous system due to alpha-synuclein aggregation, dyssynergic contractions of the puborectalis muscle, and alterations of the gut microbiome. METHOD: To conduct this study, we searched Scopus, PubMed, and Google Scholar for published articles on PD, probiotics, and constipation. We selected RCTs from 944 studies, and ultimately included 3 RCTs in our meta-analysis. The frequency of bowel movements per week was the only index that could be summarized among the records. We extracted and analyzed the results as means and standard deviations. RESULT: We calculated a standardized mean difference (SMD) of 0.92 (95% CI, 0.65 to 1.19; I-squared = 57.0%; p < 0.001) to determine the treatment effect in terms of frequency of bowel movements per week in the RCTs. CONCLUSION: Our results show that probiotic intake has beneficial effects on constipation in PD patients. Further research, including multicenter studies, is needed to assess the long-term efficacy and safety of probiotic supplements in neurodegenerative diseases.