Treating hepatitis C virus (HCV) may lower the risk of Parkinson’s disease, according to a new analysis published in JAMA Neurology.

Wey-Yil Lin, MD, of the Landseed International Hospital in Taoyuan, Taiwan, and colleagues analyzed data from the Taiwan National Health Insurance Research Database on 242,568 people with hep C, covering 2003 to 2013.

They excluded from their analysis those with a history of severe liver disease, stroke, dementia or Parkinson’s. This left a cohort of 188,152 people, 45% of whom were female. The average age was 52 years old.

The study authors divided the cohort members into two matched groups: those who did and did not receive treatment with interferon and ribavirin. (The data derived from the period before direct-acting antiviral treatment made interferon obsolete as a therapy for HCV.)

The Parkinson’s diagnosis rate per 1,000 years of follow-up was 1.0 case among those who were treated for HCV compared with 1.39 cases among those who were not treated. Five years following treatment, this difference reached statistical significance, meaning it is unlikely to have been driven by chance. At that point, interferon and ribavirin treatment was associated with a 25% reduced risk of Parkinson’s. By the end of all follow-up, this figure had increased to 29%.

The investigators concluded that their findings may support the notion that HCV is a risk factor for Parkinson’s.

To read the study, click here.