Infection with hepatitis C virus (HCV) may increase the risk of developing Parkinson’s disease (PD), according to a study from Taiwan, reported in Neurology.

Researchers followed 49,967 people with viral hepatitis and 199,868 uninfected controls for an average of 12 years. Most hepatitis patients were infected with hepatitis B virus (71.3 per cent), while 20.6 per cent had HCV and 8.1 per cent both viruses.

After allowing for con-founders – including age, sex and co-morbidities – HCV positive people were 29 per cent more likely to develop PD than controls. People infected with hepatitis B or both viruses were no more or less likely to develop PD.

PD patients show marked neuroinflammation. Previous studies suggest that viral infections can trigger inflammation. The authors remark, however, that “additional clinical studies are required to confirm the association between HCV infection, neuroinflammation, and PD”.