Effects of fecal microbiota transplantation in patients with Parkinson’s disease and amyotrophic lateral sclerosis: systematic review and meta-analysis
TL;DR
Although the intervention does not significantly reduce motor symptoms, it may be associated with consistent benefits in anxiety and constipation-related quality of life, suggesting an overall improvement in quality of life.
Abstract
Background: The gut–brain axis plays a relevant role in the pathogenesis of neurodegenerative diseases, such as Parkinson’s disease (PD) and Amyotrophic Lateral Sclerosis (ALS), in which intestinal dysbiosis may promote neuroinflammation and functional decline. In this context, Fecal Microbiota Transplantation (FMT) emerges as a promising strategy to restore eubiosis and modulate neuroactive metabolites potentially involved in the progression of these conditions. In addition to possible neuroprotective effects, FMT may contribute to reducing non-motor symptoms, such as chronic constipation and anxiety, promoting an overall improvement in quality of life. Objective: To evaluate, through a systematic review and meta-analysis following PRISMA guidelines, the effects of FMT in patients with PD and ALS, focusing on motor symptoms, anxiety, and constipation. Methods: A systematic review and meta-analysis were conducted in accordance with PRISMA guidelines, with searches performed in PubMed, Cochrane, LILACS, and WPRIM databases. Clinical trials and clinical studies assessing FMT in PD and ALS were included, considering motor, anxiety, and constipation outcomes. Four duplicates were removed; 16 studies were excluded during the initial screening and 8 after full-text review due to methodological inadequacy, incorrect population/intervention, or unavailability of the full text. Ultimately, 4 studies were included in the meta-analysis. Results: The meta-analysis included 3 studies evaluating motor symptoms (UPDRS III), totaling 64 participants in the intervention group and 66 in the control group. The UPDRS III analysis showed a standardized mean difference (SMD) of -0.85 (95% CI [-2,64; 0.93]), indicating no significant improvement with the intervention, with very high heterogeneity (I2 = 93.9%; p < 0.0001) and a non-significant global effect test (p = 0.35). In contrast, for anxiety symptoms (HAMA), 2 studies included 29 participants in the intervention group and 28 in the control group, demonstrating a significant improvement with the intervention (SMD = -0.96; 95% CI [-1.52; -0.41]; p < 0.01). Similarly, constipation-related quality of life (PAC-QOL), assessed in 2 studies with the same sample sizes, showed a significant improvement (SMD = -0.96; 95% CI [-1.52; -0.41]; p < 0.01). These findings suggest that although the intervention does not significantly reduce motor symptoms, it may be associated with consistent benefits in anxiety and constipation-related quality of life. Conclusion: FMT did not show significantimprovement in motor symptoms in PD and ALS; however, it demonstrated consistent benefits in reducing anxiety and improving constipation-related quality of life. The high heterogeneity in motor outcomes highlights the need for further well-designed studies, with larger sample sizes and methodological standardization, to better define its clinical role.