Objective Colonic Dysfunction is Far more Prevalent than Subjective Constipation in Parkinson's Disease: A Colon Transit and Volume Study

Background: Gastrointestinal function has received increased interest in the context of Parkinson's disease (PD). Constipation is among the most frequent non-motor symptoms, but our understanding of the underlying pathology is limited. Subjective constipation correlates poorly with objective markers. Objective: The aims were to evaluate colonic transit time and volume in PD and to correlate these measures with subjective symptoms and gastric emptying. Methods: Thirty-two PD patients and 26 controls were included. Colonic transit time, computed tomography-based volume estimation, and gastric emptying were performed as objective markers of gastrointestinal function. Subjective gastrointestinal symptoms were evaluated by three different questionnaires. Results: Seventy-nine percent of PD patients displayed prolonged colonic transit time (p < 0.0001) and 66% of patients had significantly increased colonic volume (p = 0.0002). Particularly the transverse and rectosigmoid segments were affected. There was no difference in gastric emptying time between groups. The prevalence of subjective constipation in PD patients was significantly lower and ranged from 3% to 38% depending on the type of questionnaire. Conclusions: Significantly delayed colonic transit time and increased volume were frequent findings in PD patients, and objective dysfunction was considerably more prevalent than subjective constipation symptoms. Also, the prevalence of subjective constipation varied widely depending upon which questionnaire was employed. These findings highlight the need for more research on how to define constipation in PD and also the need for improved understanding of the relationship between subjective symptoms and objective dysfunction.