Frequency of bowel movements and the future risk of Parkinson’s disease

TLDR

Constipation is common in Parkinson’s disease, but its timing relative to clinical onset is unclear and further study is needed to determine whether it reflects early disease processes or merely a susceptibility marker. The study aims to determine whether constipation precedes Parkinson’s disease by examining the association between bowel movement frequency and future PD risk. The authors analyzed bowel movement frequency data collected from 1971–1974 in 6,790 men aged 51–75 without PD in the Honolulu Heart Program and followed them for 24 years to identify incident PD cases. Men with fewer than one bowel movement per day had a 2.7‑fold higher risk of developing Parkinson’s disease compared with those having one per day, and a 4.5‑fold higher risk compared with those having more than two per day, after adjusting for age, smoking, coffee, laxatives, exercise, and diet.

Abstract

Constipation is frequent in PD, although its onset in relation to clinical PD has not been well described. Demonstration that constipation can precede clinical PD could provide important clues to understanding disease progression and etiology. The purpose of this report is to examine the association between the frequency of bowel movements and the future risk of PD.Information on the frequency of bowel movements was collected from 1971 to 1974 in 6790 men aged 51 to 75 years without PD in the Honolulu Heart Program. Follow-up for incident PD occurred over a 24-year period.Ninety-six men developed PD an average of 12 years into follow-up. Age-adjusted incidence declined consistently from 18.9/10,000 person-years in men with <1 bowel movement/day to 3.8/10,000 person-years in those with >2/day (p = 0.005). After adjustment for age, pack-years of cigarette smoking, coffee consumption, laxative use, jogging, and the intake of fruits, vegetables, and grains, men with <1 bowel movement/day had a 2.7-fold excess risk of PD versus men with 1/day (95% CI: 1.3, 5.5; p = 0.007). The risk of PD in men with <1 bowel movement/day increased to a 4.1-fold excess when compared with men with 2/day (95% CI: 1.7, 9.6; p = 0.001) and to a 4.5-fold excess versus men with >2/day (95% CI: 1.2, 16.9; p = 0.025).Findings indicate that infrequent bowel movements are associated with an elevated risk of future PD. Further study is needed to determine whether constipation is part of early PD processes or is a marker of susceptibility or environmental factors that may cause PD.