Gastrointestinal Dysfunction in Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disease. Patients show deposits of pathological, aggregated alpha-synuclein not only in the brain but throughout almost the entire length of the digestive tract. This gives rise to non-motor symptoms particularly within the gastrointestinal tract and patients experience a wide range of frequent and burdensome symptoms such as dysphagia, bloating, and constipation. Recent evidence suggests that progressive accumulation of gastrointestinal pathology is underway several years before a clinical diagnosis of PD. Notably, constipation has been shown to increase the risk of developing PD and in contrast, truncal vagotomy seems to decrease the risk of PD. Animal models have demonstrated gut-to-brain spreading of pathological alpha-synuclein and it is currently being intensely studied whether PD begins in the gut of some patients. Gastrointestinal symptoms in PD have been investigated by the use of several different questionnaires. However, there is limited correspondence between subjective gastrointestinal symptoms and objective dysfunction along the gastrointestinal tract, and often the magnitude of dysfunction is underestimated by the use of questionnaires. Therefore, objective measures are important tools to clarify the degree of dysfunction in future studies of PD. Here, we summarize the types and prevalence of subjective gastrointestinal symptoms and objective dysfunction in PD. The potential importance of the gastrointestinal tract in the etiopathogenesis of PD is briefly discussed.

Automated summary

Parkinson's disease is the second most common neurodegenerative disease characterized by pathological alpha-synuclein deposits in both the brain and the entire digestive tract. Gastrointestinal symptoms such as dysphagia, bloating, and constipation are common in PD patients. The accumulation of gastrointestinal pathology may begin years before a clinical diagnosis of PD, with constipation shown to increase the risk of PD and truncal vagotomy potentially decreasing the risk.