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GI Symptoms in Parkinson’s Disease Correlate With Less Microbial Diversity



Gastrointestinal symptoms are more common and severe in patients with Parkinson’s disease than in controls and may relate to an altered microbiome composition and reduced microbial diversity, according to research presented online as part of the 2020 American Academy of Neurology Science Highlights.

Jade E. Kenna, a PhD candidate and research assistant at the Perron Institute of Neurological and Translational Science in Perth, Australia, described findings from a multicenter assessment of 167 patients with Parkinson’s disease and 100 controls from movement disorders clinics in Australia. Participants completed the self-report Gastrointestinal Symptom Rating Scale (GSRS), which rates the frequency and severity of 15 GI symptoms. In addition, stool samples were analyzed using targeted sequencing to characterize gut microbiome composition.

Although Parkinson’s disease is recognized primarily as a motor disorder, GI dysfunction may be one of the first symptoms. “This is hypothesized to result from a change in microbiota towards an inflammatory, dysbiotic composition,” Ms. Kenna said. A limited number of studies have reported an association between altered microbiota composition, GI symptoms, and Parkinson’s disease, but not in Australian cohorts.

Total GSRS score was significantly higher in patients with Parkinson’s disease, compared with controls. Eight of the symptoms – heartburn, acid reflux, nausea or vomiting, borborygmus, increased flatus, decreased passage of stools, feeling of incomplete evacuation, and passing hard stools – were significantly increased in patients with Parkinson’s disease. GSRS symptoms can be categorized as upper, lower, general, hypoactive, or hyperactive, and patients with Parkinson’s disease had significantly increased ratings in the upper, lower, and hypoactive GI symptom domains.

“This is quite a novel finding as not only has this not been assessed in an Australian cohort of individuals before, but the majority of existing literature focuses on the presence of constipation only,” Ms. Kenna said. “The treatment and understanding of nonmotor symptoms of Parkinson’s disease, in particular GI symptoms, remain as one of the top unmet needs reported by patients with Parkinson’s disease themselves. Therefore, a better, more thorough understanding of these symptoms is clearly needed, and research into this area has such value in terms of improving current therapeutic approaches, management strategies, and patient education.”

Microbial analyses found that Firmicutes and Proteobacteria were significantly increased and Verrucomicrobia trended toward an increase in patients with Parkinson’s disease. Fusobacteria was increased in controls.

Proteobacteria and Verrucomicrobia are known to promote inflammation, which can lead to GI symptoms. Furthermore, Faecalibacterium and Ruminococcus, which are reduced in [Parkinson’s disease], can metabolize various substrates to produce [short-chain fatty acids] like butyrate, which are known to aid against intestinal barrier dysfunction and inflammation,” she said.

Individuals with Parkinson’s disease had significantly less microbial diversity. As Parkinson’s disease severity and GI symptom severity increased, microbiome diversity decreased, Ms. Kenna said. “As reduced diversity is associated with increased intestinal inflammation, this indicates that the altered microbiome we saw in [individuals with Parkinson’s disease] may be instigating the increase in incidence and severity of GI symptoms.”

Ms. Kenna reported that she had no disclosures.

SOURCE: Kenna JE. AAN 2020, Abstract S17.006

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