The composition of intestinal bacteria in patients with Parkinson’s disease is correlated with disease severity and a worse prognosis, a study has found.
The study, “Gut microbiota are related to Parkinson’s disease and clinical phenotype,” was published in Movement Disorders.
Parkinson’s disease is a chronic and progressive neurodegenerative disorder, caused by the gradual loss of dopamine-producing neurons in the substantia nigra, a region of the brain responsible for movement control. Although the condition is mostly associated with motor symptoms, such as tremors, body rigidity, and balance instability, patients may also experience a series of non-motor symptoms.
Gastrointestinal problems, in particular constipation, are some of the most common non-motor symptoms of Parkinson’s. They are estimated to affect up to 80 percent of all patients and can occur years before the onset of the first motor symptoms.
Previous studies have shown that gut bacteria involved in the regulation of intestinal transit interact with the nervous system, “influencing brain activity, behavior, as well as levels of neurotransmitter receptors and neurotrophic factors,” according to the study. However, the impact of intestinal bacteria in neurological disorders, such as Parkinson’s disease, had never been investigated.
“Based on the early gastrointestinal involvement in PD [Parkinson’s disease] and the vast potential of microbiome-host interactions, we … hypothesized that the fecal microbiome of PD patients differs from that of matched control subjects in terms of bacterial diversity,” the researchers wrote.
To test this hypothesis, the University of Helsinki researchers compared the composition of intestinal bacteria found in stool samples from 72 patients with Parkinson’s disease and 72 healthy controls by genetic sequencing.
Data from the observational study (NCT01536769) revealed that patients with Parkinson’s had a 77.6% reduction in the amount of bacteria belonging to the Prevotellaceae family compared with controls. This family of bacteria, which includes the Prevotella genus, is a group of nonharmful bacteria that live in the colon and help break down complex foods.
“Our findings indicate that the Prevotella associated gut microbiome enterotype [bacteria that live in the intestine] could be underrepresented among PD patients. Investigating whether high abundance of Prevotellaceae has protective effects against PD or whether low abundance is rather an indicator of disturbed mucosal barrier function will be important,” the investigators wrote.
Interestingly, the amount of bacteria from the Enterobacteriaceae family was much higher in patients with postural instability and gait difficulty than in those with tremor-dominant (TD) symptoms. This family of bacteria includes several pathogens, such as Escherichia coli, and other species of harmless bacteria.
“In comparison with TD patients, patients with a non-TD phenotype progress faster [and] have a worse prognosis. Our results suggest that this may be associated with higher abundance of Enterobacteriaceae in the fecal microbiome of non-TD patients,” the researchers wrote.
“Further studies are warranted to elucidate the temporal and causal relationships between gut microbiota and PD and the suitability of the microbiome as a biomarker,” they added.
https://parkinsonsnewstoday.com/2018/12/11/gut-bacteria-composition-correlated-parkinsons-disease-severity-study/
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