Bowel movement frequency and difficult defecation using constipation assessment scale in patients with isolated REM sleep behavior disorder.

Introduction: This study evaluated constipation, including reduced bowel movement frequency and difficult defecation, in patients with isolated rapid eye movement sleep behavior disorder (IRBD), which is prodromal Parkinson's disease (PD) or dementia with Lewy bodies (DLB) in middle-aged and older adults. Methods: We used a validated Japanese version of the Constipation Assessment Scale (CAS-J) to evaluate bowel habits over 1 month in 117 men aged 50-86 years and 34 women aged 56-86 years with video-polysomnography-confirmed IRBD and 22 controls. Furthermore, we performed a longitudinal assessment of outcomes at follow-up visits. Results: The CAS-J score was higher in the 22 IRBD patients than in 22 age- and gender-matched paired controls. In 151 IRBD patients, the CAS-J score was higher for women than for men. At baseline, the CAS-J score was similar between patients who developed PD and DLB, but the three IRBD patients who developed multiple system atrophy had a low CAS-J score. Those with constipation (CAS-J score ≥ 2) converted to PD or DLB in a significantly shorter time duration (i.e., time frame for phenoconversion) than those with CAS-J score < 2 (log-rank test, p < 0.001). When adjusted for age and gender, Cox hazards analysis revealed that the CAS-J score significantly predicted phenoconversion to PD or DLB (hazard ratio: 5.9, 95 % confidence interval: 1.8-19.1, p = 0.003). Conclusions: Constipation, i.e., reduced bowel movement frequency and difficult defecation, was common in middle-aged and elderly patients with IRBD, and CAS-J score predicted phenoconversion to PD or DLB.