Objective: Objective: To assess the impact of probiotic supplementation on depression symptoms and the gut microbiome in people living with Parkinson’s disease (PwPD).

Background: Background: PD is the second most common neurodegenerative disorder with cases slated to double between 2015 and 2040(1). While primarily characterised as a movement disorder, PwPD experience a wide range of comorbidities including disordered mood, cognition, and gastrointestinal difficulties at significantly higher rates than the general population(2,3). Given these comorbidities, evidence that PD starts in the gut in many cases, and evidence that probiotics can decrease depression symptoms, further study of probiotic supplementation of PwPD is warranted(4,5). The probiotic is a multi-strain formulation of 9 common probiotics: Mostly anaerobic, lactic acid-fermenting species implicated in SCFA synthesis.

Method: Methods: ProD is a double-blinded, randomized controlled Phase 2 feasibility pilot study  currently in the recruitment and data collection phase. PD patients (n = 60, ages 40-80, mild to moderate PD severity, mild to moderate depression) are currently being recruited at the Pacific Parkinson’s Research Centre in Vancouver, Canada. The treatment is to be taken twice daily for 12 weeks. On-site visits with biological samples are at weeks 0 and 12 with phone check-ins at weeks 4 and 8. The primary outcome is depressive symptoms. Secondary outcomes are PD motor and non-motor symptoms, cognition, anxiety, apathy, stool frequency, and more. Microbial signatures include fecal shotgun metagenomic sequencing with classification and diversity assessed with QIIME2. Microbial reads from shotgun sequencing will be classified with Kraken2, with functional profiling using Super-Focus. Inflammatory markers for this study include blood serum cytokine and metabolite analysis. Other molecules to be assayed include sex hormones, cortisol, various neurotransmitters and more. Multiple regression analysis to be adjusted for covariates as indicated. Primary analysis to be based on intention-to-treat

Results: Results: Actively recruiting and collecting data. Preliminary data will be available for presentation by October 2025.

Conclusion: Conclusions: This study will help illuminate connections between the gut-brain axis and PD, as well as provide evidence for a larger Phase 3 trial.

References: References
1. Dorsey ER, Sherer T, Okun MS, Bloem BR. The emerging evidence of the Parkinson pandemic. J Parkinsons Dis. 2018;8(s1):S3–8.
2. Fasano A, Visanji NP, Liu LWC, Lang AE, Pfeiffer RF. Gastrointestinal dysfunction in Parkinson’s disease. Lancet Neurol. 2015 Jun;14(6):625–39.
3. Marsh L. Depression and Parkinson’s disease: current knowledge. Curr Neurol Neurosci Rep. 2013 Dec;13(12):409.
4. Braak H, Rüb U, Gai WP, Del Tredici K. Idiopathic Parkinson’s disease: possible routes by which vulnerable neuronal types may be subject to neuroinvasion by an unknown pathogen. J Neural Transm (Vienna). 2003 May;110(5):517–36.
5. Akkasheh G, Kashani-Poor Z, Tajabadi-Ebrahimi M, Jafari P, Akbari H, Taghizadeh M, et al. Clinical and metabolic response to probiotic administration in patients with major depressive disorder: A randomized, double-blind, placebo-controlled trial. Nutrition. 2016 Mar;32(3):315–20.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/probiotic-treatment-for-depression-and-associated-mood-disorders-in-parkinsons-disease-a-randomized-placebo-controlled-trial-short-title-prod/