Lin WY, Lin MS, Weng YH, et al. - In a cohort study of 188,152 patients with hepatitis C virus (HCV) infection, researchers identified the risk of Parkinson disease (PD) development in patients with HCV infection who were receiving antiviral treatment, as well as in patients who were not receiving this treatment. An equal number (n = 39,936) and similar features of participants were engaged in the treated group and untreated group following matching. The incidence density of PD was 1.00 and 1.39 per 1,000 person-years, respectively, in the treated group and in the untreated group. The advantage of antiviral therapy attained statistical importance at the 5-year follow-up, and this advantage proceeded to rise until the end of follow-up. Thus, in patients with chronic HCV infection who received interferon-based antiviral therapy, lower PD incidence was evident—supporting the hypothesis that HCV could be a risk factor for PD.