A recent study has strengthened the hypothesis that Parkinson’s disease may originate in the gut, challenging the longstanding belief that it begins in the brain. Researchers discovered that individuals with upper gastrointestinal issues, such as ulcers and esophageal damage, are at a higher risk of developing Parkinson’s later in life. “A growing body of evidence suggests that, at least for some individuals, Parkinson’s disease starts in the gut before impacting the central nervous system,” stated Trisha S. Pasricha, a neurogastroenterologist and director of Clinical Research at the Institute for Gut-Brain Research at Beth Israel Deaconess Medical Center (BIDMC).

Pasricha explained to The Harvard Gazette, “Many people with Parkinson’s experience gastrointestinal symptoms like constipation and nausea for years—sometimes decades—before showing motor symptoms such as tremors or difficulty walking. Our research aims to shed light on this ‘gut-first’ pathway of Parkinson’s disease, which could lead to new strategies for early intervention and treatment.”

This fresh perspective on Parkinson’s may reshape how we approach its early detection and management. Understanding the gut-brain connection could pave the way for more effective strategies to manage symptoms and slow disease progression. Dr. Pranav Honnavara Srinivasan, a consultant gastroenterologist at Fortis Hospital Bengaluru, provides insights into this development.

The ‘Gut-First’ Hypothesis Gains Traction

The Harvard study presents compelling evidence for the ‘gut-first’ hypothesis of Parkinson’s disease. Dr. Srinivasan elaborates, “Researchers found that misfolded alpha-synuclein proteins, crucial to Parkinson’s progression, can originate in the gut and travel to the brain via the vagus nerve. This supports the notion that the disease may initiate in the gastrointestinal tract, where it can remain dormant before affecting the brain.”

This theory contrasts with the traditional ‘brain-first’ hypothesis, which posits that Parkinson’s begins in the brain and later impacts other areas, including the gut. The growing support for the ‘gut-first’ theory is bolstered by numerous reports from Parkinson’s patients who experience gastrointestinal issues—like constipation—years prior to the onset of motor symptoms.

Gastrointestinal Conditions as Early Warning Signs

Dr. Srinivasan emphasizes the significance of gastrointestinal symptoms for early detection. “Chronic conditions such as constipation, ulcers, and esophageal damage are now recognized as potential early indicators of Parkinson’s. The Harvard study suggests these issues may reflect underlying problems within the enteric nervous system, where misfolded proteins could accumulate before spreading to the brain.”

He points out that patients with chronic gut issues may be at an increased risk of developing Parkinson’s. “Symptoms like constipation can emerge decades before motor dysfunction, providing a crucial window for diagnosis. Esophageal problems, including difficulty swallowing or acid reflux, may also indicate disruptions in gut-brain communication, potentially serving as early markers of Parkinson’s.”

Changing Approaches to Diagnosis and Prevention

This new understanding of Parkinson’s origins could lead to significant shifts in diagnostic and preventive care. Dr. Srinivasan proposes that doctors start screening for gastrointestinal symptoms, particularly in high-risk individuals, such as those with a family history of Parkinson’s or long-standing digestive issues.

“By identifying and monitoring individuals with chronic constipation or gut inflammation, we could develop early interventions to slow or prevent the disease’s progression to the brain.” This approach may also change preventive care strategies, with an emphasis on promoting gut health through diet, probiotics, and other interventions to reduce Parkinson’s risk.

Emerging Treatments Targeting the Gut-Brain Axis

The focus on the gut-brain connection is opening new treatment avenues. Dr. Srinivasan notes, “Emerging therapies are increasingly focusing on the gut-brain axis as a potential intervention point for Parkinson’s. Probiotics and microbiome-modulating treatments are being explored to restore gut health, which may help mitigate protein misfolding in the gut and slow disease progression.”

He adds that anti-inflammatory treatments targeting the gut and therapies that modulate the vagus nerve are also under investigation. While these treatments are still in the experimental phase, early trials show promise.

Dr. Srinivasan concludes, “The evolving research from Harvard and other institutions offers new hope for Parkinson’s patients by underscoring the gut’s critical role in the disease’s development. By addressing gastrointestinal symptoms early, we may significantly alter the course of the disease.”