There has long been speculation that viral infection may cause dopamine responsive Parkinson’s disease — at least in a subset of patients. The most famous case examples were depicted in the 1990 movie Awakenings starring Robin Williams and Robert De Niro (based on Oliver Sacks’ 1973 memoir) where Parkinsonian patients (presumed to have been suffering from a viral flu or sleeping sickness) awaken when exposed to dopamine. Though more common viruses have been considered as potential Parkinson’s disease triggers, there has been a lack of evidence to support this notion. Tsai and colleagues recently studied hepatitis C virus (HCV) infection as a potential risk factor for the later development of Parkinson’s disease. In this month’s What’s Hot column we will explore this potential association.
Tsai acquired data from the Taiwan National Health Insurance Research Database. The data was drawn from a ten-year period and included 49,967 patients with viral hepatitis (hepatitis B, hepatitis C, or both B and C co-infection) and 199,868 patients without hepatitis. The authors reported an association between HCV and the later development of Parkinson’s disease. There was not a clear association with the other forms of hepatitis. The authors adjusted the data to be sure age, sex, and other medical diseases did not influence the results. They concluded that in this Taiwanese cohort, HCV infection increased the risk of later developing Parkinson’s disease.
The idea that viruses such as HCV can enter the brain and lead to Parkinson’s related cell loss is not new (substantia nigra or the black dopamine containing brain cells). This recent study documented a strong association. The large number of patients in the Taiwanese cohort lends credence to the findings. The results must be interpreted cautiously because of the lack of diagnostic certainty of PD, and because of the missing details in the case histories (details such as transfusion history, drug abuse and other potentially important factors). Also, the findings will need to be replicated in other countries. Patients and family members should be aware that a diagnosis of HCV may be a risk factor for the later development of Parkinson’s disease. The threshold for seeking a neurological examination if you have HCV and potential Parkinsonian symptoms should probably be lower. What we don’t know is whether treating the HCV infection will reduce the later risk for the development of Parkinson’s disease.
You can find out more about our National Medical Director, Dr. Michael S. Okun, by also visiting the Center of Excellence, University of Florida Health Center for Movement Disorders and Neurorestoration. Dr. Okun is also the author of the Amazon #1 Parkinson's Best Seller 10 Secrets to a Happier Life and 10 Breakthrough Therapies for Parkinson's Disease. You can read more from Dr. Okun in the What's Hot in PD? archives.