Infections with the viruses that cause hepatitis B and hepatitis C are associated with increased rates of Parkinson’s disease (PD), according to a study published in the March 29 online edition of Neurology. More research is needed to explain this connection.
Hepatitis is a general term for an inflamed liver. Certain viruses can cause hepatitis, including the hepatitis B and C viruses, leading to serious illness. Yet many people carry these viruses for years and do not realize it. A person can also develop hepatitis when their immune system cells mistakenly attack the liver, so-called autoimmune hepatitis.
Recent research from Taiwan suggested a link between hepatitis C and PD. Following up on this finding, researchers led by Michael Goldacre, M.Sc., F.F.P.H., F.R.C.P., at the University of Oxford in the United Kingdom, examined hospital records entered in a large, national British database between 1999 and 2011. From these they culled the records of people admitted with a first case of hepatitis B, hepatitis C, autoimmune hepatitis, chronic active hepatitis or HIV (a different viral infection). The researchers compared these records with records from more than six million people with minor conditions unrelated to viral infections, e.g., ingrown toenails or appendectomy.
- The researchers identified hospital records from nearly 22,000 people with hepatitis B, 48,000 with hepatitis C, 6,000 with autoimmune hepatitis, 4,000 with chronic active hepatitis and nearly 20,000 with HIV.
- People with hepatitis B were 76 percent more likely to develop Parkinson’s than those in the comparison group (44 people with hepatitis B developed PD, compared to the 25 cases that would be expected in the general population).
- People with hepatitis C were 51 percent more likely to develop PD than those in the comparison group (73 people developed PD, whereas about 49 cases would be expected in the general population).
- People with autoimmune hepatitis, chronic active hepatitis or HIV did not have an increased rate of PD.
What Does It Mean?
The study finds a significantly increased risk of PD among people infected with the hepatitis B or C viruses — relatively common viruses that are likely carried by several million Americans. This association opens many questions, which should be examined by follow up studies.
The study authors suggest that the increased risk of PD could be the result of something specific to hepatitis B and C (as opposed to other types of hepatitis). In this case, infection with these viruses might increase PD risk. An alternative explanation to the association is that PD and viral hepatitis share underlying mechanisms, or share a genetic or environmental susceptibility. Alternatively, it is possible that the treatments for viral hepatitis could induce PD symptoms as has rarely been reported. More research is needed to confirm the nature of the connection between hepatitis B and C and PD, the result of which could potentially advance a broader understanding of the causes of PD.
"This study adds to existing evidence linking viral hepatitis and Parkinson's, although it does not yet explain why this connection exists," added James Beck, Ph.D., Chief Scientific Office, Parkinson's Foundation. "That said, the results may point us toward a promising area of research. Knowledge of this link may help scientists to pinpoint mechanisms underlying Parkinson's, which would advance research into better treatments for millions worldwide."
Pakpoor J, Noyce A, Goldacre R, et al. (2017). Viral Hepatitis and Parkinson Disease: A National Record-Linkage Study. Neurology 88: 1-4