A study in Kerala sheds light on the link between gut bacteria and Parkinson’s disease

Researchers found higher levels of bacteria potentially associated with inflammation and lower levels of beneficial bacteria that produce short-chain fatty acids that help maintain a healthy gut lining and regulate the immune system in patients with Parkinson’s disease. | Photo credit: Getty Images/iStockphoto

Trillions of bacteria living in the human gut may play a role in Parkinson’s disease, a brain disorder that causes tremors, stiffness and slowed movements, according to a new study involving patients from Kerala.

Researchers from Cochin University of Science and Technology (CUSAT) and Sree Chitra Tirunal Institute for Medical Sciences and Technology (SCTIMST), Thiruvananthapuram, have found significant differences between the gut bacteria of Parkinson’s disease patients and that of healthy individuals. The findings were published online in npj Parkinson’s Disease, an international scientific journal.

Parkinson’s disease occurs when nerve cells in the brain that produce dopamine, a chemical that helps control movement, gradually die. Scientists have long suspected that the gut and brain are in constant communication, and that an imbalance of gut bacteria could contribute to inflammation affecting the brain. Studies have shown that non-motor symptoms, including constipation and other gastrointestinal problems, can appear years before the onset of tremors in patients with Parkinson’s disease.

The study involved 65 patients with Parkinson’s disease attending the SCTIMST Comprehensive Care Center for Movement Disorders and 65 healthy individuals, most of whom were spouses of the patients. Spouses were included as healthy subjects for comparison, as they were more likely to share similar diets and living conditions.

Metagenomic sequencing

The researchers analyzed the stool samples using metagenomic sequencing (16S rRNA gene amplicon sequencing), a technique that identifies the bacteria present and helps assess their potential functions in the gut. In patients with Parkinson’s disease, they found higher levels of bacteria potentially associated with inflammation and lower levels of beneficial bacteria that produce short-chain fatty acids that help maintain a healthy gut lining and regulate the immune system.

The researchers suggest that a shift in bacterial communities could weaken the gut barrier and allow inflammation to spread.

“The study found that differences in the abundance of these bacteria were strongly associated with disease severity and other clinical features of Parkinson’s disease,” said Baby Chakrapani PS, director of the Neuroscience Center and assistant professor in the Department of Biotechnology at CUSAT. “The findings also suggest that gut bacteria may be linked to disease progression through their influence on processes involving dopamine, glutamate and GABA, chemicals that play an important role in brain function.”

The study, funded by the Indian Council of Medical Research (ICMR), was conducted by Aneesa PA, Research Associate at CUSAT, under the supervision of Mr. Chakrapani and Dr. Syama Krishnan of SCTIMST.

The composition of gut bacteria is influenced by factors such as diet, age, gender and lifestyle. Differences in these factors, as well as genetics, could explain why studies in different populations report inconsistent associations between specific bacteria and Parkinson’s disease.

According to the researchers, this is the first study in an Indian population to integrate the composition of the gut microbiome with its functional role in Parkinson’s disease. The findings could help future research into simple tests for early disease diagnosis and treatments aimed at restoring gut health.

Published – 29 Oct 2026 10:44 IST