A team of researchers at Johns Hopkins Medicine may have discovered the link between psychiatric disorders, such as schizophrenia, bipolar disorder and major depression, and viral infections.

In the breakthrough study published in the journal Translational Psychiatry, scientists uncovered the hepatitis C virus (HCV) in the choroid plexus of the brain. For the study, researchers analyzed brain tissue in postmortem subjects both with and without psychiatric disorders along with the electronic medical records of 285 million people.

The choroid plexus, which is a network of blood vessels and specialized cells found within the ventricles of the brain, is responsible for producing cerebrospinal fluid (CSF) that protects the brain and spinal cord. This part of the brain also plays a crucial role in forming the blood-CSF barrier, which regulates the passage of substances between the blood and the CSF. The presence of the liver-damaging HCV in this region suggests that the virus might play a previously unrecognized role in altering brain chemistry and immune signaling, potentially triggering or worsening psychiatric symptoms.

The researchers found that more viruses were present in brain tissue samples from people suffering from schizophrenia or bipolar disorder. But, unlike other viruses, HCV was found only in the brain lining of these people. And not all people with HCV had the virus in the brain lining, suggesting that the infection doesn’t always spread to the choroid plexus.

The discovery could lead to new pathways of diagnosis and treatment for those suffering from psychiatric illnesses.

"Some people with symptoms of bipolar disorder or schizophrenia may actually have a hepatitis C infection instead,” explained study leader Sarven Sabunciyan, a neuroscientist and associate professor of pediatrics at the Johns Hopkins University School of Medicine. “Potentially, treating the viral infection will improve the psychiatric symptoms in these people.”

Sabunciyan told Newsmax: “It's worth investigating the presence of viruses in the brain lining in other brain disorders such as Alzheimer's disease and multiple sclerosis where a virus has been suggested to be involved in the disease."