Category: Parkinson's Disease: Non-Motor Symptoms
Objective: To evaluate whether patients with PD exhibit 1) a bloom in sulfate-reducing bacteria based on the detection of hydrogen-sulfide (H2S) during lactulose breath testing and 2) an association between H2S and clinical outcomes.
Background: Gastrointestinal dysfunction occurs early in the course of PD, with evidence that it can develop up to 20 years prior to diagnosis. A perturbed gut microbiome (dysbiosis) characterized by a bloom in sulfate-reducing bacteria may be particularly important to PD disease pathogenesis or progression.1,2 We hypothesize that patients with PD exhibit elevated H2S following lactulose ingestion, suggestive of a bloom in sulfate-reducing bacteria.
Method: 16 PD and 17 matched HC underwent motor assessments, comprehensive neuropsychological evaluation, and a lactulose breath test that included H2, CH4, and H2S measurements. Chi-squared tests evaluated whether patients with PD exhibited higher rates of small intestinal bacterial overgrowth (SIBO) or H2S positivity relative to HC. Bootstrap analyses evaluated whether patients with PD exhibited increased gastrointestinal symptoms and H2, CH4 and H2S levels relative to HC accounting for age and sex. Finally, Spearman correlation analyses evaluated associations between H2, CH4 and H2S levels and clinical outcomes (age of onset, motor and cognitive symptoms).
Results: Patients with PD reported significantly more gastrointestinal symptoms relative to HC, including: more severe frequency and levels of current constipation (p<0.001), lifetime frequency of stools (p=0.048), and severity of stool strain (p=0.006). Both groups had elevated rates of SIBO (SIBO Positive: 70.59% PD; 70.59% HC). 62.5% of the patients with PD were H2S positive, whereas only 29.41% of the HC were H2S positive, though this did not significantly differ based on chi-squared tests (p = 0.12). However, mean and max H2S were inversely associated with both age of first PD symptom (mean: rho=-0.36, p=0.03) and visuospatial functioning (mean: rho=-0.39, p=0.03).
Conclusion: Our results highlight elevated gastrointestinal symptoms in PD relative to HC, despite similar, high rates of SIBO across both groups. A bloom in sulfate-reducing bacteria may contribute to earlier disease onset and worse visuospatial functioning. Future work in larger cohorts is necessary to further understand if a bloom in sulfate-reducing is present early in the disease course and if it progresses with clinical symptoms.
References: 1. Murros KE, Huynh VA, Takala TM, Saris PEJ. Desulfovibrio bacteria are associated with Parkinson’s disease. Front Cell Infect Microbiol. 2021;11:652617.
2. Ryman S, Vakhtin AA, Richardson SP, Lin HC. Microbiome–gut–brain dysfunction in prodromal and symptomatic Lewy body diseases. J Neurol. 2023;270(2):746-758.
To cite this abstract in AMA style:
K. Julio, A. Vakhtin, H. Lin, A. Birg, N. Hoffman, S. Nitschke, N. Shaff, E. Erhardt, A. Mayer, D. Sugar, G. Suarez Cedeno, A. Deligtisch, S. Pirio Richardson, S. Ryman. Gastrointestinal Dysbiosis and Clinical Outcomes in Parkinson’s Disease [abstract]. Mov Disord. 2024; 39 (suppl 1). https://www.mdsabstracts.org/abstract/gastrointestinal-dysbiosis-and-clinical-outcomes-in-parkinsons-disease/. Accessed October 5, 2024.« Back to 2024 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/gastrointestinal-dysbiosis-and-clinical-outcomes-in-parkinsons-disease/