A new study by scientists at Johns Hopkins Medicine has found the hepatitis C virus (HCV) in the choroid plexus which is the fluid-producing lining of the brain, they are said to be found in individuals diagnosed with schizophrenia and bipolar disorder.
The findings, published 14 July in Translational Psychiatry, suggest a potential biological link between viral infection and psychiatric symptoms in a subset of patients.
Choroid Plexus Linked to Viral Presence in Psychiatric Conditions
The study, which is led by Dr. Sarven Sabunciyan, investigated the choroid plexus rather than brain tissue, based on its susceptibility to viral infections.
The team, using high-throughput sequencing on postmortem brain tissue, identified more viral presence in individuals diagnosed with schizophrenia and bipolar disorder. The Twist panel enabled detection across thousands of viruses. One particular virus emerged repeatedly in affected samples.
HCV Exclusively Detected in Schizophrenia and Bipolar Brain Linings
Hepatitis C virus (HCV) was identified solely in the choroid plexus of individuals diagnosed with schizophrenia and bipolar disorder. It was absent in samples from those with major depressive disorder and in unaffected control subjects.
The virus was not present in every person with chronic HCV, suggesting variability in how the infection reaches brain structures. “Our findings show that it’s possible that some people may be having psychiatric symptoms because they have an infection,” said Dr. Sabunciyan.
“And since the hepatitis C infection is treatable, it might be possible for this patient subset to be treated with antiviral drugs and not have to deal with psychiatric symptoms.”
Health Record Analysis Confirms Disparity in HCV Prevalence
The researchers examined anonymised electronic health records from the TriNetX database to further test their hypothesis, representing 285 million patients globally. The data showed HCV prevalence in:
- 3.6% of those with schizophrenia
- 3.9% with bipolar disorder
- 1.8% with major depression
- 0.5% of the general control population
Researchers also tested whether drug use could explain these findings. They found that substance use alone did not account for the increased rates of HCV among patients with schizophrenia and bipolar disorder compared to those with depression, suggesting a biological factor beyond behavioural risk.
HCV May Influence Brain Without Direct Infection of Brain Tissue
Although the virus was not found in the hippocampus—the region responsible for memory and cognitive function—HCV’s presence in the brain lining appeared to alter gene expression in that area. Therefore it supports the theory that peripheral infections can still impact central brain function through inflammatory or genetic signalling pathways.
The Johns Hopkins team now plans to explore the potential of screening psychiatric patients for HCV to determine whether antiviral treatment could reduce or eliminate some symptoms.
“We hope to collaborate with mental health professionals to screen for HCV in people with bipolar disorder and schizophrenia to learn whether treating the infection will ease or stop symptoms,” Sabunciyan said.