[Frequency of bowel movements and risk of Parkinson's disease: a prospective cohort study in adults in China].

Objective: To evaluate the association between the frequency of bowel movement (BMF) and the risk of Parkinson's disease (PD). Methods: In this study, 510 134 participants from the China Kadoorie Biobank (CKB) were included after excluding those who reported to had been diagnosed with cancer at baseline survey. The baseline survey was conducted from 2004 to 2008. The study used the data from the baseline survey and follow-up until December 31, 2016. Cox proportional hazards regression models were used to estimate the HRs and the 95%CIs of risk of PD diagnosis with BMF. Results: During an average follow-up period of (9.9±1.9) years, 808 participants were diagnosed with PD. Compared with participants who had bowel movements every day, the multivariable-adjusted HR (95%CI) for those who had bowel movements<3 times/week, once every 2-3 days, and>1 time/day were 3.62 (2.88-4.54), 2.13 (1.74-2.60), and 0.81 (0.63-1.05), respectively. The linear trend test results of the association between BMF and risk of PD diagnosis was significant (P<0.001). Compared with the participants who had bowel movements ≥1 time/day, the multivariable-adjusted HR (95%CI) for those who had bowel movements<1 time/day was 3.13 (2.32-4.23) within the 5 years of follow- up and was 2.48 (2.05-3.01) beyond the 5 years of follow-up. The gender specific results were similar. The association of BMF<1 time/day with risk of PD diagnosis was stronger in older participants. Conclusions: The participants with low BMF at baseline survey would have higher risk for PD diagnosis in the subsequent 10 years on average. Since abnormal decrease of BMF is easy to be found, programs could be set up for the early screening of PD in older people, along with other early symptoms of PD.