Gastrointestinal manifestations in Parkinson's disease: prevalence and occurrence before motor symptoms

To assess the prevalence of gastrointestinal symptoms (GIS) in Parkinson's disease (PD) compared to control subjects and their timing of appearance in relationship to the onset of motor symptoms. There is a rostrocaudal gradient of alpha-synuclein (α-SYN) neuropathology in the enteric nervous system at early stages of PD with higher burden in the upper than the lower gut. However, only constipation has been recognized as a premotor gastrointestinal manifestation of PD. 129 PD patients and 120 controls underwent a structured questionnaire to assess the presence of GIS and, in PD patients, the time of their appearance respect to the onset of motor manifestations. GIS significantly more prevalent in PD patients were dry mouth, drooling, dysphagia, constipation and defecatory dysfunction. Constipation and defecatory dysfunction preceded motor manifestations. Whereas gastroparesis symptoms preceded motor manifestations, their prevalence was not significantly different from controls. Despite evidence of a higher α-SYN burden in the upper gut, only constipation and defecatory dysfunction were prominent premotor GIS of PD.