Amyotrophic Lateral Sclerosis: The State of the Art on Treatments and the Therapeutic Role of the Intestinal Microbiome in Human Studies

Amyotrophic lateral sclerosis (ALS) is a common neurodegenerative disorder; to date, there is no long-term effective treatment. Recently, a relationship has been discovered between the human intestinal microbiome and the pathogenesis of ALS, on which basis faecal microbiota transplantation (FMT) has been proposed as a potential treatment for ALS. In this review, we compare three existing case studies examining the effect of FMT on the course of ALS, highlighting differences in methodology and results. In two of the studies, a halt in the progression of ALS symptoms was observed following FMT, accompanied by improvement in patient health. However, in the third and largest study, no significant effect of FMT was observed. The possible explanation for this discrepancy may be the intentional depletion of intestinal microorganisms using antibiotics prior to FMT in the third study. Future studies and/or completion of the ongoing clinical studies will help clarify the therapeutic effectiveness of FMT in ALS patients.