Hepatitis C infection may increase the risk of Parkinson’s disease, according to a nationwide population-based study published online ahead of print December 23, 2015, in Neurology. Researchers analyzed 10 years of data from the Taiwan National Health Insurance Research Database, which included 49,967 patients with viral hepatitis—35,619 with hepatitis B infection, 10,286 with hepatitis C, and 4,062 with both—and 199,868 noninfected controls.
Individuals with hepatitis C infection had a 29% greater incidence of Parkinson’s disease after adjustment for confounders such as sex, age, heart disease, stroke, and head injury. The researchers found no significant associations between hepatitis B or coinfection and Parkinson’s disease risk.
Age was the most common risk factor for Parkinson’s disease across all cohorts, and in the control group, comorbidities such as hyperlipidemia, hypertension, ischemic heart disease, diabetes, and head injury all were associated with a significant increase in the risk of Parkinson’s disease. Among individuals with hepatitis C infection, however, only ischemic heart disease and head injury remained significantly associated with Parkinson’s disease risk.
The possibility of an association between hepatitis C infection and Parkinson’s disease has emerged recently, with evidence showing that the virus is neurotropic and can replicate in the CNS, reported Hsin-Hsi Tsai, MD, a neurologist at the National Taiwan University Hospital in Taipei, and coauthors.
“Parkinsonism is rarely a described feature in patients with hepatitis C virus. However, a recent study has discovered that hepatitis C virus can induce dopaminergic neuron death, suggesting a possible association between hepatitis C virus infection and” Parkinson’s disease, said the authors.
The study also showed that the association between hepatitis C infection and Parkinson’s disease was more significant in individuals younger than 65, who had a 61% greater risk of developing the neurodegenerative disease.
“Some of the risk factors for hepatitis C virus infection, such as illicit drug use and associated behaviors, may be confounding factors in this age group,” said the authors. They pointed out, however, that in Taiwan, use of IV drugs was not known to be a risk factor for infection. Commenting on a possible mechanism for the association between hepatitis C infection and Parkinson’s disease, Dr. Tsai and associates suggested that the hepatitis C virus could be a possible viral candidate for triggering the neuroinflammation that is a characteristic feature of Parkinson’s disease.
“An earlier imaging study that involved using magnetic resonance spectroscopy to investigate the cerebral effect of hepatitis C virus showed that chronic hepatitis C virus infection was associated with elevated choline/creatinine ratios, a biomarker indicating inflammatory and infective conditions, in the basal ganglia and white matter,” they said.
—Bianca Nogrady