The new study involved 49,967 people with hepatitis and 199,868 people without hepatitis. Participants with hepatitis were placed into three groups: those infected with Hepatitis B Virus (71 percent), those with Hepatitis C Virus (21 percent), and those who had both viruses (8 percent). The participants were followed for an average of 12 years to see who developed Parkinson’s disease. Of those with hepatitis, 270 developed Parkinson’s disease, including 120 people with hepatitis C. Among those who did not have hepatitis, 1,060 developed Parkinson’s disease.
|[Stages in Parkinson's Disease]|
While the exact causes of Parkinson's are unclear, past studies have suggested it may be triggered by a combination of environmental and genetic factors. Pinpointing the possible causes of Parkinson's is key to finding a much-needed cure, and this latest research may have uncovered another risk factor for the disease.
“Many factors clearly play a role in the development of Parkinson’s disease,” said study author Chia-Hung Kao from China Medical University in Taichung, Taiwan. “This nation-wide study, using the National Health Insurance Research Database of Taiwan, suggests that hepatitis caused specifically by the Hepatitis C Virus may increase the risk of developing the disease. More research is needed to investigate this link.”
The World Health Organization estimates that 130 to 150 million people have hepatitis C worldwide. While Hepatitis C can lead to serious illness, many people have few symptoms and do not even realize they have the virus, especially at first.
 Hsin-Hsi Tsai et al: Hepatitis C virus infection as a risk factor for Parkinson disease in Neurology - 2015