Parkinson’s disease is a neurodegenerative disorder that affects nerve cells in the substantia nigra, a part of the midbrain that controls muscle movement. Symptoms include tremor, rigidity, slowed movement and difficulty with balance. You can have a genetic risk of developing the disease if you have an affected first-degree relative – a parent, child or sibling – or if you have had significant exposure to herbicides and pesticides. Men are more likely to develop Parkinson’s disease than women.
Hepatitis C is a chronic viral infection of the liver that causes inflammation and tissue damage. The virus is transmitted by infected blood via blood transfusions, hemodialysis, or by sharing needles with intravenous drug users. The infection progresses slowly and can destroy liver cells and impair liver function even before obvious symptoms develop.
Hepatitis B is a serious liver infection caused by a different virus (HBV), spread via contact with blood and body fluids of an infected person as a result of unprotected sex, sharing needles, razors or toothbrushes or getting a tattoo or piercing with unsterilized tools. While a percentage of individuals will develop a chronic infection, most affected adults recover fully, even if their signs and symptoms are severe.
Research from Taiwan published in 2016 established a connection between hepatitis C and Parkinson’s. One year later, a study from the UK’s University of Oxford found an association between both hepatitis B and C and Parkinson’s. The Oxford researchers examined British hospital records of people diagnosed with a first case of hepatitis B, hepatitis C, autoimmune hepatitis, chronic active hepatitis and HIV from 1999 to 2011. They checked the records later to see which of these patients developed Parkinson’s. Results showed a 76 percent increased risk of Parkinson’s among people with hepatitis B and a 51 percent increased risk among those with hepatitis C. No additional risk was seen in people with autoimmune hepatitis, chronic active hepatitis or HIV.
In actual numbers, the study found that 44 people with hepatitis B developed Parkinson’s compared to 25 cases expected in the general population. Among people with hepatitis C, 73 developed Parkinson’s, compared to 49 cases expected in the general population. The researchers noted that they were unable to adjust for lifestyle factors, such as smoking and alcohol use, which could affect the risk for Parkinson’s.
The reasons for the newly recognized connections aren’t yet known. Study author Julia Pakpoor suggests, “The hepatitis virus itself or perhaps the treatment for the infection could play a role in triggering Parkinson’s.” Another possibility: “People who are susceptible to hepatitis infections are also more susceptible to Parkinson’s disease,” she said, adding that the researchers hope that “identifying this relationship may help us to better understand how Parkinson’s disease develops.”
According to the Centers for Disease Control and Prevention (CDC), an estimated 850,000 to 2.2 million people in the United States have chronic hepatitis B and 2.7 to 3.9 million people have chronic hepatitis C. Parkinson’s disease affects an estimated one million people in the U.S. and 10 million worldwide.
Andrew Weil, M.D.
Julia Pakpoor et al, “Viral hepatitis and Parkinson disease. ” Neurology, March 29, 2017, doi.org/10.1212/WNL.0000000000003848