Obsessive-Compulsive Disorder and Risk of Parkinson Disease: A Nationwide Longitudinal Study

Several small-scale studies have suggested a biological link between obsessive-compulsive disorder (OCD) and Parkinson disease (PD). However, the temporal association of OCD and subsequent PD remained unclear.Here, we used Taiwan National Health Insurance Research Database and included the data of 28,722 patients with OCD ( International Classification of Diseases, Ninth Revision, Clinical Modification code: 300.3) and 287,220 matched controls between 2001 and 2009. They were followed until the end of 2011 to identify diagnosis of new-onset PD ( International Classification of Diseases, Ninth Revision, Clinical Modification code: 332.0). The frequency of psychiatric outpatient visits for OCD per year (<5, 5-10, and >10) was identified as a proxy of OCD severity.Using the stratified Cox regression model, the hazard ratio of developing PD among patients with OCD was 2.70 (95% confidence interval = 1.74-4.18) compared with matched controls. Among patients with OCD, those with >10 psychiatric outpatient visits per year for OCD (hazard ratio = 3.18, 95% confidence interval = 2.06-4.93) were more likely to develop PD during the follow-up period compared with those with <5 psychiatric outpatient visits per years for OCD.OCD was found to be an independent risk factor for PD. The mechanisms underlying the temporal association between OCD and subsequent PD require further investigation.