REM sleep behavior disorder correlates with constipation in de novo Chinese Parkinson's disease patients

Background Constipation, rapid eye movement sleep behavior disorder (RBD) and hyposmia are common prodromal symptoms of Parkinson's disease (PD), and they may represent two distinct types of disease origin, from the body or the brain. Our study aimed to compare the clinical characteristics of de novo PD patients with and without constipation and identify which prodromal symptoms were associated with constipation. Methods A total of 111 de novo, drug-naive Chinese PD patients were consecutively enrolled from Jan 2017 to Sept 2021. Patients were classified into PD with and without constipation based on item 5 of the Scales for Outcomes in Parkinson's disease-Autonomic Dysfunction (SCOPA-AUT). The demographic data, motor, and non-motor symptoms were compared between the two groups. The associated factors of constipation were analyzed by the multivariate logistic regression analysis. Results In total, 44.1% (n= 49) of de novo PD patients had constipation. PD patients with constipation were older (p = 0.028), had higher proportions of Hoehn and Yahr (H-Y) stage >= 2 (p = 0.002), clinical possible RBD (cpRBD) (p = 0.002) and depression (p = 0.023), as well as marginal increase of hyposmia (p = 0.058) and freezing of gait (p = 0.069). After adjusting for H-Y stage and other confounding factors, cpRBD (OR =3.508, p =0.009), rather than hyposmia or depression, was closely related to constipation in de novo Chinese PD patients. Conclusions RBD is closely associated with constipation in de novo Chinese PD patients. Our results support the theory that prodromal symptoms that represent the same pathological origin are closely related to each other.