Risk of Parkinson's disease among patients with herpes zoster: A nationwide longitudinal study

Several studies suggested a potential role of viral infection in the pathophysiology of Parkinson's disease (PD). However, the association between herpes zoster and PD was not investigated well till now. Methods Using the Taiwan National Health Insurance Research Database, 13 083 patients aged ≥45 years with herpes zoster and 52 332 (1:4) age-/sex-matched controls were enrolled between 1998 and 2008 and followed to the end of 2011. Those who developed PD during the follow-up period were identified. Results The Cox regression analysis with adjustment of demographic characteristics, health system utilization, and comorbidities demonstrated that patients with herpes zoster had an increased risk (hazard ratio [HR]: 1.80, 95% confidence interval [CI]: 1.43-2.28) of developing PD in later life compared to the control group. Sensitivity tests after excluding the first year (HR: 1.50, 95% CI: 1.16-1.93) and first 2-year (HR: 1.44, 95% CI: 1.10-1.88) observation periods showed consistent results. Conclusions Patients with herpes zoster were more likely to develop PD in later life compared to the controls. Additional studies are necessary for validating our results and to clarify the underlying pathophysiology between herpes zoster and PD.