Parkinson's disease linked to hepatitis

Hepatitis B and C infections increase the risk of developing Parkinson’s disease, according to researchers who used data from England collected between 1999 and 2011.

The researchers compared the risk of developing Parkinson’s disease in 100,390 patients with hepatitis B, hepatitis C, autoimmune hepatitis, chronic active hepatitis or HIV and approximately 6.1 million controls. People with hepatitis B and C were 76% and 51% more likely to develop Parkinson’s disease than controls. The 59% increase in PD risk among people with autoimmune hepatitis was not statistically significant, probably because relatively few people had this uncommon condition.

Plausibly, healthcare professionals may diagnose Parkinson’s disease more often because people with hepatitis B and C are followed more closely than controls (so-called surveillance bias). In addition, theoretically, pre-existing Parkinson’s disease could increase the risk of contracting hepatitis, but the liver disease was detected first (so-called reverse causality).