Which way does the axis tip? IBD increases the risk of Parkinson’s disease

In Gut , Villumsen et al 1 report a statistically significant association between UC and the risk of parkinsonism in a Danish nested case–control study. Patients with Crohn’s disease and UC with at least one inpatient or outpatient encounter for IBD between 1977 and 2014 were compared with age-matched and sex-matched controls (76 477 IBD; 7 548 259 controls). Follow-up started at the time of the first IBD encounter (or the corresponding date for the controls) until the first diagnosis of Parkinson’s disease or multiple system atrophy. Parkinsonism was increased among patients with UC (HR 1.35 (95% CI 1.20 to 1.52)), but not Crohn’s disease (HR 1.12 (95% CI 0.89 to 1.40)). Parkinson’s disease and multiple system atrophy were rare both in patients …