Inflammatory bowel disease and Parkinson’s disease

We read with interest the study by Villumsen et al on the risk of Parkinson’s disease (PD) in patients with IBD.1 This study took advantage of the long series of nation-wide data from 1977 to 2014 in the Danish Population and Patient Registers. For each person ever living in Denmark during this period, the register data include dates of birth, immigration, emigration, death, diagnosis with IBD and diagnosis with PD. This allows for a cohort design with accumulation of person-years and …