Hepatitis B and C may be linked to increased incidence of Parkinson's disease

In a study to examine the associations between viral hepatitis and Parkinson’s disease (PD), researchers discovered that the viruses hepatitis B and C may both be associated with an increased risk of Parkinson’s disease, according to a study published in the March 29, 2017, online issue of Neurology^®, the medical journal of the American Academy of Neurology.

It is estimated that anywhere from 850,000 to 2.2 million people in the United States have chronic hepatitis B virus infection and anywhere from 2.7 to 3.9 million people have chronic hepatitis C, according to data from the Centers for Disease Control and Prevention (CDC). While both viruses can lead to serious illness, many people manifest few symptoms and do not realize they have the virus, especially initially.

Researchers explained that hepatitis B is spread through contact with blood and body fluids of an infected person, such as through unprotected sex, sharing needles, getting a tattoo or piercing with unsterilized tools, or sharing razors or toothbrushes with an infected person.

Hepatitis C is spread through blood-to-blood contact such as sharing needles, razors, and toothbrushes and is passed on at birth by infected mothers.

“The development of Parkinson’s disease is complex, with both genetic and environmental factors,” said study author Julia Pakpoor, BM, BCh, of the University of Oxford in the United Kingdom. “It’s possible that the hepatitis virus itself or perhaps the treatment for the infection could play a role in triggering Parkinson’s disease or it’s possible that people who are susceptible to hepatitis infections are also more susceptible to Parkinson’s disease. We hope that identifying this relationship may help us to better understand how Parkinson’s disease develops.”

In the study, researchers went through hospital records from a large British database. They examined records of people with a first case of hepatitis B, hepatitis C, autoimmune hepatitis, chronic active hepatitis, and HIV from 1999 to 2011. Then those people were compared with the hospital records of people with relatively minor conditions such as cataract surgery, bunions, and knee replacement surgery. For all of the participants, researchers looked at the records to see who subsequently developed Parkinson’s disease.

Study authors found that there were 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. They were compared with more than 6 million people with minor conditions.

The study found that people with hepatitis B were found to be 76% more likely to develop Parkinson’s disease than those in the comparison group; and people with hepatitis C were found to be 51% more likely to develop Parkinson’s disease. A total of 44 people with hepatitis B developed Parkinson’s disease, compared with 25 cases that would be expected in the general population. For individuals with hepatitis C, 73 of them developed Parkinson’s disease, where about 49 cases would have been expected in the general population.

People who had autoimmune hepatitis, chronic active hepatitis, and HIV did not have an increased rate of developing Parkinson’s disease.

A previous study from Taiwan demonstrated a relationship between hepatitis C and Parkinson’s disease, but it did not show any relationship with hepatitis B.

Pakpoor stated that limitations of the current study include that they could not adjust for lifestyle factors such as smoking and alcohol use, which could affect Parkinson’s disease risk; and that the study was based solely on people who were evaluated at a hospital.

Other authors involved in the study included Alastair Noyce, MRCP, PhD; Raph Goldacre, MSc; Marianna Selkihova, MRCP, PhD; Stephen Mullin, BSc, MRCP; Anette Schrag, FRCP, PhD; Andrew Lees, FRCP, MD; and Michael Goldacre, FFPH, FRCP.

The British National Institute for Health Research funded the development of the datasets and software.