Studies on gut bacteria in Parkinson’s disease differ in their findings and important methodological details, according to a new review that highlights these differences and proposes strategies to mitigate them in the future.

The study, titled “ Increasing Comparability and Utility of Gut Microbiome Studies in Parkinson’s Disease: A Systematic Review,” was published in the Journal of Parkinson’s Disease.

Although Parkinson’s is often thought of as a disorder of the brain, the gut likely plays an important role in the disease, but it has only been seriously studied in recent years. A number of studies have recently focused on how the gut microbiome — the bacteria that live inside the intestines — might impact Parkinson’s.