Effects of probiotic supplementation on gastrointestinal motility, inflammation, motor and non-motor symptoms in Parkinson's disease: a meta-analysis of randomized controlled trials

Abstract

Parkinson’s disease (PD) is the second most common neurodegenerative disease. It is believed that “gut dysbiosis” can cause PD; therefore, whether probiotics can be used as adjuvants in the treatment of PD is being actively investigated. We performed a systematic review and meta-analysis to evaluate the effectiveness of probiotic therapy in PD patients. PUBMED/MEDLINE, EMBASE, Cochrane, Scopus, PsycINFO and Web of Science databases were searched till January 9, 2023. The meta-analysis used a random effects model and the effect size was calculated as mean difference or standardized mean difference. Ten studies with 760 participants were included in the final analysis. The meta-analysis revealed a significant improvement in gastrointestinal motility (standardized mean difference [95% confidence interval]) (0.78 [0.57-0.98]) and antioxidant capacity (1.73 [0.26 to 3.21]). Serum inflammatory markers (-8.64 [-16.05 to -1.23]), diabetes risk (-3.41 [-4.65 to -2.17]), Unified PD Rating Scale Part III (-4.12 [-7.81 to -0.43]), non-motor symptom (-5.55 [-8.30 to -2.80]), quality of life (-1.13 [-1.86 to -0.40]), anxiety scale (-2.21 [-3.41 to -1.00]) and depression scale (-1.53 [-1.99 to -1.07]) demonstrated a significant decrease. The Bristol stool scale, constipation and risk of dyslipidemia were not significantly improved. In a subgroup analysis, capsules further improved gastrointestinal motility than fermented milk. This review found that probiotic supplements may be suitable for increasing gastrointestinal motility, reducing inflammation, and improving motor and non-motor symptoms of PD. Further research is warranted to determine the mechanism of action of probiotics and the optimal treatment protocol.