Despite being recognised primarily as a motor disorder, gastrointestinal (GI) dysfunction is one of the first symptoms reported by individuals with Parkinson’s disease (PD). This is hypothesised to result from a change in microbiota towards an inflammatory, dysbiotic composition.

Results indicate that PD patients have significantly worse GI symptoms (e.g. acid reflux, decreased passage of stools and nausea/vomiting (p < 0.05)), when compared to healthy controls. Subsequently, the study identified that both relative abundance and diversity of microbial phyla/genera were significantly different in patients with PD when compared to healthy controls (p<0.05). Specifically, Firmicutes, Proteobacteria and Verrucomicrobia were all increased within PD. Reduced microbial diversity was significantly associated with greater disease and GI symptom severity.