“Growing evidence suggests an increasing significance for the extent of gastrointestinal tract (GIT) dysfunction in Parkinson’s disease (PD). Most patients suffer from GIT symptoms, including dysphagia, sialorrhea, bloating, nausea, vomiting, gastroparesis, and constipation during the disease course. The underlying pathomechanisms of this α-synucleinopathy play an important role in disease development and progression, i.e., early accumulation of Lewy pathology in the enteric and central nervous systems is implicated in pharyngeal discoordination, esophageal and gastric motility/peristalsis impairment, chronic pain, altered intestinal permeability and autonomic dysfunction of the colon, with subsequent constipation.”

“Dysfunction of the upper GIT in PD, especially oropharyngeal dysphagia, are complex syndromes occurring early in disease that often remain unnoticed until severe complications, such as aspiration pneumonia, become manifest. In the lower GIT, constipation is a widespread and debilitating symptom with the potential of leading to severe bowel complications and even cognitive dysfunction.”
Warnecke T, et al Gastrointestinal involvement in Parkinson’s disease: pathophysiology, diagnosis, and management. NPJ Parkinsons Dis. 2022 Mar 24;8(1):31. Free Full Text