Experimental studies showing motor symptom improvement induced by probiotic interventions in PD.
| Study (year) | Probiotic(s) | Duration | Dose/Presentation | Motor outcome |
|---|---|---|---|---|
| Human studies | ||||
| Lu et al. (2021) [53] | Lactobacillus plantarum PS128 | 12 weeks | Two capsules containing PS128 (30 billion colony-forming units per capsule) daily, oral | Improvement in UPDRS motor scores in both ON and OFF states (p = 0.004 and 0.007, respectively). Decreased akinesia subscores in the OFF state (p = 0.012). Reduced duration of OFF periods (p = 0.04) and increased ON periods (p = 0.031). |
| Sun et al. (2022) [82] | Probio-M8 (Bifidobacterium animalis subsp. lactis) | 3 months | 2 g of Probio-M8 powder (3 × 1010 CFU/day; maltodextrin as excipient) daily | Significant reduction in UPDRS part III at 1 and 3 months (p = 0.037, 0.016, respectively). |
| Zali et al. (2024) [104] | BioZen D® containing: Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus reuteri, Lactobacillus paracasei, Bifidobacterium longum, Bacillus coagulans + vitamin D | 12 weeks | 2 × 109 CFU + 400 IU vitamin D per capsule, 1 oral capsule a day | Significant improvement in all MDS-UPDRS domains (parts I, III, and IV), except for part II (p ≤ 0.001). |
| Zeng et al. (2024) [93] | Bacteroides fragilis 839 + earthworm protein supplement | 12 weeks | 10 g of BF839 + earthworm protein supplement solution (contains 106 BF839 and 0.3 g earthworm protein) dissolved in 200 mL of water, twice daily | Reduction in all UPDRS subscale scores, including part III (p varying from 0.001 to 0.026 in UPDRS parts I to IV). |
| In vivo studies of animals | ||||
| Hsieh et al. (2020) [105] | Bifidobacterium bifidum, Bifidobacterium longum, Lactobacillus rhamnosis, Lactobacillus rhamnosus GG, Lactobacillus plantarum LP28, Lactococcus lactis subsp. Lactis | 16 weeks | 1010 CFU/mouse/day, oral | Improved balance and coordination (beam walking test and reduced traversal time, p < 0.05 to p < 0.001), and gait (measured by walking speed, step length, stride length, step width, stance and swing phase times, p < 0.05); preserved TH + dopaminergic neurons in substantia nigra pars compacta (p < 0.05). |
| Sun et al. (2021) [56] | Clostridium butyricum | 4 weeks | 5 × 108 CFU/mouse/day, intragastric | Shorter pole descent times, reduced beam latency and foot slips, decreased immobility, and increased open field crossings (all with a p < 0.01). |
| Parra et al. (2023) [106] | Microbiot®: Lactobacillus rhamnosus GG + Bifidobacterium animalis ssp. lactis Bb12) | 15 days | 1 × 109 CFU/strain/day, oral | Partial motor benefits: reduced type 3 step errors (day 7, p < 0.05) and improved stand phase (day 13, p < 0.01). |
| Castelli et al. (2020) [18] | SLAB51 (Bifidobacterium and Lactobacillus strains) | 5 weeks (2 pre + 3 post-lesion) | Oral gavage, daily (dose not specified in summary) | Restored contralateral forelimb use (p < 0.005), reduced biased swings (p < 0.005), and decreased apomorphine-induced rotations (p < 0.005). |
| Wang et al. (2023) [58] | Clostridium butyricum-pMTL007-GLP-1 (engineered strain expressing GLP-1) | 7 days | 1 × 108 CFU/mL, oral gavage, resuspended in saline with 0.01% gelatin | Significant motor improvement in MPTP-induced PD mice: reduced pole test descent time (p < 0.01), improved hanging wire test score, increased total distance traveled, and central area exploration in the open field test (both p < 0.01). |
PD: Parkinson’s disease; MDS-UPDRS: Movement Disorder Society-Unified Parkinson’s Disease Rating Scale; TH: tyrosine hydroxylase; MPTP: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine.
SPG: Conceptualization, Formal analysis, Investigation, Methodology, Project administration, Resources, Supervision, Visualization, Writing—original draft, Writing—review & editing. DHT: Conceptualization, Formal analysis, Investigation, Resources, Writing—original draft. FES: Conceptualization, Formal analysis, Investigation, Resources, Writing—original draft. GEB: Conceptualization, Project administration, Supervision, Writing—review & editing. MCRO: Conceptualization, Project administration, Supervision, Writing—review & editing. MGB: Conceptualization, Project administration, Supervision, Writing—review & editing, Funding acquisition. All authors read and approved the submitted version.
All authors meet the authorship criteria as defined by the International Committee of Medical Journal Editors (ICMJE), declare that they have no conflicts of interest, and confirm that no related papers from the same study, nor any similar manuscripts, have been published elsewhere.
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Miguel Germán Borda was supported by the Norwegian Health Association. In addition, this paper represents independent research supported by the Norwegian government, through hospital owner Helse Vest (Western Norway Regional Health Authority). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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