World Parkinson's Disease Day 2025: How digestive health may hold the key to Parkinson’s care

World Parkinson's Day, celebrated every year on April 11, is a strong reminder of the high-impact nature of this neurodegenerative disorder. It also points towards an increasingly prominent field of research that is changing our view of this complicated neurological disorder by finding unconventional links and symptoms to the disease, like the gut-brain axis.
For decades, Parkinson's disease (PD) has primarily been studied by taking inferences from motor symptoms and neurodegeneration in the brain. However, emerging scientific developments emphasize the gut plays a vital role in PD, a concept that has tremendous implications for early diagnosis, treatment, and disease prevention.
Parkinson’s disease has typically been characterized by symptoms such as tremors, rigidity, and bradykinesia. However, patients may present non-motor symptoms such as constipation or gastrointestinal dysfunction, which occur earlier in the disease process than the motor symptoms, including tremors, rigidity and bradykinesia. Dr Viviane Labrie and her co-authors published a pivotal study, which found that patients who had chronic constipation had a greater baseline risk of experiencing Parkinson’s disease at a later time and was found as a red flag for the disease process. This correlation was not merely incidental. The study suggested that pathological alpha-synuclein — the protein that accumulates abnormally in PD — may first appear in the enteric nervous system of the gut well before it reaches the brain.
Further strengthening this theory, a comprehensive study led by Dr. Heiko Braak proposed the "Braak Hypothesis," which postulates that environmental toxins or pathogens could initiate PD pathology in the gastrointestinal tract. From there, through the vagus nerve — the critical superhighway between the gut and the brain — these misfolded proteins might travel and spark neurodegeneration. Notably, supportive evidence from a JAMA Neurology (2016) study observed that individuals who had undergone vagotomy (a surgical procedure to remove the vagus nerve) had a considerably lower likelihood of developing Parkinson's disease later in life, providing clinical support in a real-world context to this hypothesis.

What does this mean for patients and caregivers? In simple terms, our gastrointestinal health may not only give clues, but it could also provide an important opportunity in the fight against Parkinson’s. Identifying and addressing gut-associated symptoms early could also help in timely diagnosis and decrease disease progression. Additionally, research is underway to determine whether a range of interventions aimed at altering the gut microbiome (e.g., diet, probiotics, and prebiotics) could be utilized therapeutically. For example, clinical trials at Johns Hopkins and the University of Helsinki are researching whether altering the gut microbiome could decrease neuroinflammation and improve PD symptoms.
As we explore the effects of Parkinson's, the gut-brain axis reminds us of the need for wider approaches towards neurodegenerative care. Being more informed about digestive health empowers the patients, while also strengthening their pathways to more effective, personal treatment options. As we observe World Parkinson's Awareness Day, we should widen the narrative to incorporate gut health as a key message, support early screening of gastrointestinal symptoms, and keep supporting holistic research that will change the way we approach this difficult disease.
(By Dr. Sanjay Pandey, Professor and Head, Neurology and Stroke Medicine, Amrita Hospital, Faridabad)