Gastrointestinal Dysfunction in Parkinson's Disease

Parkinson's disease is an age-associated neurodegenerative disorder characterised by motor deficits due to dopaminergic neuronal loss, but non-motor manifestations such as gastrointestinal dysfunction often emerge years earlier. Symptoms range from dysphagia and sialorrhoea to delayed gastric emptying, small-intestinal transit delay and chronic constipation, impacting quality of life and complicating medication absorption. Accumulation of misfolded α-synuclein in the enteric nervous system and subsequent propagation via the vagus nerve underpin the gut-brain axis hypothesis, suggesting the gastrointestinal tract as a potential initiation site for disease pathology. Objective assessments reveal that subjective symptom scales frequently underestimate the extent of motility impairments, highlighting the importance of diagnostic tools such as manometry, scintigraphy and wireless motility capsules. Untreated gastrointestinal symptoms can exacerbate malnutrition, dehydration and suboptimal pharmacotherapy, emphasising the clinical imperative for early recognition and multidisciplinary management strategies.

Research from Nature Portfolio

Recent investigations have characterised constipation as affecting around 61 % of patients and identified it as preceding motor onset in nearly a quarter of cases. Older age, advanced disease stage, and greater motor and non-motor symptom burden—including cognitive and emotional disturbances—emerged as predictors of constipation severity. Multivariable analysis demonstrated that age, disease stage and neuropsychiatric factors independently increased constipation risk, underlining the multifactorial nature of gastrointestinal involvement in Parkinson’s disease and its substantial impact on activities of daily living and quality of life.

Gastrointestinal Dysfunction in Parkinson's Disease publication trend

The graph below shows the total number of articles in gastrointestinal dysfunction in parkinson's disease across all publications each year (not limited to Nature Index journals).

Technical terms

α-Synucleinopathy: Accumulation of misfolded α-synuclein protein within neurons, a pathological hallmark of Parkinson’s disease.

Enteric nervous system (ENS): Network of neurons governing gastrointestinal motility and secretion independent of the central nervous system.

Gastroparesis: Delayed gastric emptying in the absence of mechanical obstruction, leading to nausea and bloating.

Small intestinal bacterial overgrowth (SIBO): Excessive bacterial proliferation in the small intestine, resulting in bloating, diarrhoea and nutrient malabsorption.

Probiotics: Live microorganisms that, when administered in adequate amounts, confer health benefits by modulating the gut microbiota.

Tyrosine decarboxylase: Enzyme produced by certain gut bacteria that converts levodopa to dopamine in the gut, reducing its therapeutic availability.

References

1. Gastrointestinal Dysfunctions in Parkinson’s Disease: Symptoms and Treatments. Parkinson's Disease (2016).
2. The gut-brain axis and Parkinson disease: clinical and pathogenetic relevance. Annals of Medicine (2021).
3. Gastrointestinal Dysfunction in Parkinson’s Disease. Journal of Clinical Medicine (2021).
4. Gastrointestinal involvement in Parkinson’s disease: pathophysiology, diagnosis, and management. npj Parkinson's Disease (2022).
5. Parkinson disease with constipation: clinical features and relevant factors. Scientific Reports (2018).
6. Efficacy and safety of probiotics in Parkinson’s constipation: A systematic review and meta-analysis. Frontiers in Pharmacology (2023).
7. Mechanisms of peripheral levodopa resistance in Parkinson’s disease. npj Parkinson's Disease (2022).