Study Links Gut Bacteria Composition to Several Markers of Parkinson’s

The variability and abundance of gut bacteria are associated with several early risk markers of Parkinson’s disease, particularly those related to motor impairments and constipation, study finds.

Future studies investigating the impact of gut bacteria composition on the risk of Parkinson’s and on its early manifestations are needed, researchers noted.

The study, “Gut microbiome signatures of risk and prodromal markers of Parkinson’s disease,” was published in the journal Annals of Neurology.

Changes in gut bacteria composition, the presence of alpha-synuclein deposits in the gastrointestinal (GI) tract, and persistent constipation in patients with clinically-confirmed and prodromal (early) Parkinson’s, all indicate the gut plays a key role in the development of the disease.

“However, little is known about whether such alterations [in gut bacteria composition] precede disease onset and how they relate to risk and prodromal markers of [Parkinson’s disease],” researchers wrote.

To investigate the possible relationship between gut bacteria composition and known risk and prodromal markers of Parkinson’s, researchers analyzed the diversity and abundance of gut bacteria found in patient stool samples.

They then correlated their findings with 18 pre-established risk and prodromal markers, which were estimated based on information found in patient medical records regarding diet, lifestyle, GI function, and medication history.

The study was based on data from 666 patients with a mean age of 68.4 years, who participated in the Tübingen evaluation of Risk factors for Early detection of NeuroDegeneration (TREND) study, a study designed to collect information on early markers of Parkinson’s and Alzheimer’s disease.

From the 18 risk and prodromal markers considered, sex, physical activity, constipation, smoking, occupational solvent exposure, and REM‐sleep behavior disorder (RBD), all were found to be associated with different measures of gut bacteria diversity.

Patients’ age and the use of medications that reduce urate levels also were found to be associated with different measures of gut bacteria diversity. Notably, higher urate levels have been associated with a lower risk of developing Parkinson’s disease.

Researchers also found that patients who had lower levels of physical activity and those who had constipation tended to have a higher number of bacteria belonging to the Firmicutes phylum in their stool samples.

Conversely, those who had a higher number of bacteria belonging to the Prevotella genus were found to be less likely to have constipation and early motor deficits associated with parkinsonism.

Moreover, differences in the abundance of gut bacteria species were found to be linked to constipation, physical activity, RBD, smoking, and motor impairments indicative of parkinsonism.

However, no clear associations were found between gut bacteria composition and other risk and prodromal markers of Parkinson’s, including depression, olfactory loss, urinary and erectile dysfunction, and family history of the disease.

“Several risk and prodromal markers of PD are associated with gut microbiome composition. However, the impact of the gut microbiome on PD risk and potential microbiome-dependent subtypes in the prodrome of PD need further investigation,” the researchers concluded.