A recent study suggests that the hepatitis C virus (HCV) might be involved in the development of psychiatric conditions like schizophrenia, bipolar disorder, and major depressive disorder.
Longstanding Suspicions About Viruses and Mental Illness
Researchers have long observed correlations between certain mental health disorders and viral infections, yet direct detection of these viruses in the human brain has remained elusive.
Now, scientists have discovered remnants of 13 different viruses in the brain’s protective barrier. Among them, HCV showed a notably strong correlation with both schizophrenia and bipolar disorder when compared to individuals without these conditions.
Led by a research team from Johns Hopkins University, the study examined postmortem brain tissue from individuals diagnosed with schizophrenia, bipolar disorder, and major depression, as well as from unaffected control subjects.
The researchers focused their attention on the choroid plexus—a network of capillaries and connective tissue that regulates the production of cerebrospinal fluid (CSF). CSF cushions the brain and spinal cord, clears metabolic waste, and manages the exchange of various molecules between the brain and body.
Viral Target Identified in Brain Lining
Because the choroid plexus is known to be susceptible to viral infections—and because earlier studies found few viral markers in brain tissue itself—the team believed this structure might offer more clues.
They obtained brain samples from the Stanley Medical Research Institute, which maintains a repository of tissues from individuals with psychiatric conditions.
To identify hidden viral material, the team used the Twist Comprehensive Viral Research Panel, a tool capable of detecting more than 3,000 viruses in human samples.
HCV Stands Out Among Viral Candidates
Their investigation uncovered several viral signatures in the choroid plexus, particularly in patients with schizophrenia or bipolar disorder.
Although a broader range of viruses appeared in these samples, HCV was the only virus that showed a statistically meaningful connection to mental illness.
This led the team to highlight HCV in their effort to better understand potential links between viral infections and psychiatric disorders.
In the next stage of the study, the researchers analyzed TriNetX, a massive database containing electronic health records from 285 million individuals.
HCV Rates Higher in Schizophrenia and Bipolar Disorder
This broader data set revealed HCV in 3.5% of patients with schizophrenia and 3.9% of those with bipolar disorder.
Those numbers contrast sharply with the 1.8% of patients with major depression and only 0.5% of healthy controls who had HCV, indicating a significantly higher prevalence among those with schizophrenia or bipolar disorder.
Interestingly, while researchers also examined the hippocampus—a brain region essential for memory, emotion, and learning—they found no viral evidence there.
Still, even though the hippocampus appeared virus-free, patients who had HCV in their brain lining showed changes in gene expression within the hippocampus, suggesting the virus may exert an indirect influence from the brain’s outer layer.
Need for Further Research and Therapeutic Potential
The researchers emphasize that more studies are necessary to understand how viruses like HCV might interact with the brain and influence psychiatric symptoms. They also caution that HCV is unlikely to be the sole cause of these conditions.
However, the findings could open the door to new treatment approaches, according to Sarven Sabunciyan, a neuroscientist at Johns Hopkins.
Our results indicate that, for some individuals, psychiatric symptoms might stem from an infection, says Sabunciyan. Since hepatitis C is treatable, antiviral therapy could potentially relieve symptoms in a subset of patients who otherwise would face long-term psychiatric care.
Read the original article on: Science Alert
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