• The Role of Gut Microbiome in Parkinson’s Disease Progression: From Dysbiosis to Novel Therapeutics
  • Hessan Hosseinzadeh Bandbafha,1,* Bahare Pakpour,2 Maryam Tajabadi Ebrahimi,3
    1. Department of Biology, CT.C., Islamic Azad University, Tehran, Iran.
    2. Department of Biology, CT.C., Islamic Azad University, Tehran, Iran
    3. Department of Biology, CT.C., Islamic Azad University, Tehran, Iran


  • Introduction: Parkinson’s disease (PD) is a progressive neurological disorder characterized by the loss of dopaminergic neurons in the substantia nigra, leading to both motor and non-motor symptoms. Alterations in the gut microbiome play a critical role in disease progression. Dysbiosis can increase intestinal permeability, systemic inflammation, and disrupt the gut-brain axis, exacerbating neuronal damage and PD symptoms. Probiotics, particularly Lactobacillus paracasei and Bacillus coagulans, modulate the gut microbiome and reduce inflammation, improving motor and non-motor symptoms. This review examines molecular mechanisms, preclinical and clinical evidence, and the therapeutic potential of probiotics in PD management.
  • Methods: This article presents a systematic review of studies published between 2015 and 2025 investigating the relationship between gut microbiome and Parkinson’s disease. Databases searched included PubMed, Web of Science, Scopus, SID, and Magiran. Keywords included “Parkinson’s disease,” “gut microbiome,” “probiotics,” “dysbiosis,” and “gut-brain axis.” Inclusion criteria comprised preclinical and clinical studies providing experimental data on the effects of probiotics or microbiome alterations on PD symptoms. Non-relevant, duplicate, and low-quality studies were excluded.
  • Results: Dysbiosis and PD: Animal and human studies indicated that decreased microbial diversity and increased inflammatory bacteria are associated with PD severity. Probiotics and symptom improvement: Lactobacillus paracasei supplementation improved motor symptoms and increased BDNF expression. Bacillus coagulans and inflammation: Reduced inflammatory cytokines, including IL-6 and TNF-α, improving non-motor symptoms. Clinical studies: Co-administration of probiotics and vitamin D decreased disease severity and improved quality of life in PD patients.
  • Conclusion: Evidence suggests that gut-brain axis and dysbiosis play crucial roles in PD progression. Probiotics can modulate the gut microbiome, reduce systemic inflammation, and increase neurotrophic gene expression, providing protective effects and symptom improvement. Further studies combining probiotics with diet or pharmacotherapy could lead to novel therapeutic strategies. Dysbiosis and PD: Animal and human studies indicated that decreased microbial diversity and increased inflammatory bacteria are associated with PD severity. Probiotics and symptom improvement: Lactobacillus paracasei supplementation improved motor symptoms and increased BDNF expression. Bacillus coagulans and inflammation: Reduced inflammatory cytokines, including IL-6 and TNF-α, improving non-motor symptoms. Clinical studies: Co-administration of probiotics and vitamin D decreased disease severity and improved quality of life in PD patients.
  • Keywords: Parkinson’s disease, gut microbiome, dysbiosis, probiotics, gut-brain axis