Objectives Imbalances in the composition and function of intestinal microbes have been reported in neurological and other diseases. We sought to determine whether faecal microbe composition differs between motor neuron disease (MND) patients and an age- and sex-matched control population.

Methods MND (n=26) and control participants (n=24) provided faecal samples for 16S gDNA analysis of the presence of bacteria and archaeal species. For MND participants, body composition, metabolic status, site of symptom onset, and functional capacity (as determined by ALSFRS-R) was recorded. 16S metagenomics aggregate reports were completed for each sample (2017 Illumina, Inc.), and the entropy of species-level classifications determined across all samples using the Shannon Species Diversity index. Functional and species diversity interactions are currently under assessment using PICRUSt and QIIME data analysis pipelines.

Results In all participants metagenomics aggregate reports revealed an increase in species diversity within individuals with increasing age. Compared with control participants, a higher number of faecal microbial species, and a greater species diversity were observed in MND patients. The greater species diversity was primarily seen in patients with bulbar onset disease.

Conclusions Greater diversity of faecal microbe content in MND participants with bulbar onset disease suggest that changes in the gut microbiome composition in this cohort of patients could occur secondary to changes in dietary intake as a consequence of dysphagia. Ongoing studies aim to clarify these findings in a larger cohort of individuals, while considering the functional implications of a shift in gut microbe diversity in MND.