Probiotics for Parkinson's disease: Current evidence and future directions

Abstract

The gut–brain axis is a hot topic in Parkinson's disease (PD). It has been postulated that gut pathogens and dysbiosis can contribute to peripheral inflammatory states or trigger downstream metabolic effects that exacerbate the neurodegenerative process in PD. Several preclinical and clinical studies have demonstrated disrupted intestinal permeability, intestinal inflammation, altered gut microbiome, and reduced fecal short‐chain fatty acids in PD. In this regard, microbial‐directed therapies such as probiotics are emerging as potential therapeutic options. Probiotic supplementation is postulated to confer a variety of health benefits due to the diverse functions of these live microorganisms, including inhibition of pathogen colonization, modulation/“normalization” of the microbiome and/or its function, immunomodulatory effects (e.g. reducing inflammation), and improved host epithelial barrier function. Interestingly, several PD animal model studies have demonstrated the potential neuroprotective effects of probiotics in reducing dopaminergic neuronal degeneration. Notably, two randomized placebo‐controlled trials have provided class I evidence for probiotics as a treatment for constipation in PD. However, the effects of probiotics on other PD aspects, such as motor disability and cognitive function, and its long‐term efficacy (including effects on PD drug absorption in the gut) have not been investigated adequately. Further targeted animal and human studies are also warranted to understand the mechanisms of actions of probiotics in PD and to tailor probiotic therapy based on individual host profiles to improve patient outcomes in this disabling disorder.

The Possible Role of Bifidobacterium longum BB536 and Lactobacillus rhamnosus HN001 on Locomotor Activity and Oxidative Stress in a Rotenone‐Induced Zebrafish Model of Parkinson’s Disease

“…The most powerful vehicle used in clinical practice to diminish PD-related symptomatology and the associated comorbidities causative or not are probiotics [13]. These are live microorganisms known to have a helpful role in improving digestive function [14,15].…”

Probiotics: Not just good for the gut but for the brain too

“…In this issue of JGH Open , Tan et al . have summarized some of the current evidence for the role of probiotics in PD 6 . They reported that probiotics not only led to a reduction in neurotoxic metabolites but was able to improve motor function in studies conducted on mouse models of PD.…”

“…Constipation is extremely common, causing significant distress to patients with PD, and is notoriously resistant to current laxatives 7 . Two randomized controlled trials have demonstrated the superiority of multistrain probiotics over placebo in improving constipation in PD over a 4‐week period 6 …”

“…5 In this issue of JGH Open, Tan et al have summarized some of the current evidence for the role of probiotics in PD. 6 They reported that probiotics not only led to a reduction in neurotoxic metabolites but was able to improve motor function in studies conducted on mouse models of PD. Probiotics have also been shown to downregulate proinflammatory cytokines and upregulate anti-inflammatory cytokines in cellular model studies using blood samples from PD patients.…”

“…7 Two randomized controlled trials have demonstrated the superiority of multistrain probiotics over placebo in improving constipation in PD over a 4-week period. 6 As constipation is recognized to predate the onset of motor symptoms in PD, 8 it is possible that prolonged or higher doses of probiotics may be able to reduce debilitating motor symptoms, but this is yet to be proven. PD is also known to have a significant number of nonmotor symptoms such as cognitive impairment, anxiety, depression, and psychosis.…”