Association of Tic Disorders and Enterovirus Infection A Nationwide Population-Based Study

There has been growing interest in the association between infectious disease and mental disorders, but an association between enterovirus (EV) infection and tic disorders has not been sufficiently explored. Herein, we aim to investigate the association between EV infection and incidence of tic disorders in a nationwide population based sample using Taiwan's National Health Insurance Research Database. We identified individuals aged <= 18 years prior to 2005 with an inpatient diagnosis of EV infection and/or history of EV infection. Tic disorder was operationalized using International Classification of Disease, Revision 9, Clinical Modification (ICD-9-CM) codes 307.20-307.23. A total of 47,998 individuals with history of EV infection were compared to 47,998 sex-, age-, and urbanization-matched controls on incidence of tic disorders. The mean +/- standard deviation follow-up period for all subjects was 9.7 +/- 3.6 years; the mean latency period between initial EV infection and incident diagnosis of tic disorder diagnosis was 5.4 +/- 2.8 years. EV infection was significantly associated with greater incidence of tic disorders (hazard ratio [HR] = 1.24, 95% CI: 1.07-1.45). When subgrouped on the basis of central nervous system (CNS) involvement, EV infection with CNS involvement was not significantly associated with greater incidence of tic disorders when compared to controls (HR = 1.25, 95% CI: 0.64-2.43); EV infection without CNS involvement was significantly associated greater incidence of tic disorders when compared to controls (HR = 1.24, 95% CI: 1.07-1.45). In addition, hospitalization for an EV infection did not increase the hazard for greater incidence of tic disorders (HR = 1.32, 95% CI: 1.04-1.67 with hospitalization and 1.22, 95% CI: 1.04-1.44 without hospitalization). EV infection is temporally associated with incidence of tic disorders. Our observations add to the growing body of literature implicating immune-inflammatory system in the pathoctiology of brain disorders in a subpopulation of individuals and serve as a clarion call for surveillance of symptoms suggestive of tic disorders in individuals with history of EV infection.