Scientists have located an intriguing link between schizophrenia and the Epstein-Barr virus, a type of herpes virus. Now, they need to determine which way the risk lies.

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A new study may have found another environmental risk factor linked to schizophrenia.

Schizophrenia, a condition characterized by a confused perception of reality, delusions, and altered behavior, affects more than 21 million people globally.

In a new study, specialists from Johns Hopkins Medicine in Baltimore, MD, and the Sheppard Pratt Health System in Townson, MD, found evidence that links schizophrenia with the Epstein-Barr virus.

This is a herpes virus that causes infectious mononucleosis, or glandular fever.

As the scientists report in a paper published in the Schizophrenia Bulletin, they saw higher levels of antibodies against the Epstein-Barr virus in the bodies of those with schizophrenia than in those of people without any mental health conditions.

The higher level of antibodies suggests exposure to the virus, but it is unclear which way the risk runs — that is, whether infection with the Epstein-Barr virus renders people more vulnerable to schizophrenia, or whether schizophrenia impacts the immune system and exposes people to infections.

"We are interested in the role of infectious agents such as Epstein-Barr virus in schizophrenia and other serious psychiatric disorders, so we did this study to look at the associations," says senior study author Dr. Robert Yolken.

A link between schizophrenia and infection?

Research has identified certain genetic risk factors for schizophrenia, but it has also recognized the possibility that some environmental factors — including exposure to infections — can raise schizophrenia risk.

In the new study, the scientists worked with 743 participants, of whom 432 had schizophrenia and 311 had no mental health problems (the control group). Around 55 percent of the cohort was male.

Dr. Yolken and colleagues compared the levels of antibodies against the Epstein-Barr virus in the participants with schizophrenia with those of participants in the control group.

They saw that people with schizophrenia were 1.7–2.3 times more likely than controls to have higher antibody levels against this herpes virus.

These participants did not have higher antibody levels against other types of infections, such as varicella (or chickenpox) or the herpes simplex type 1 virus, which is mainly transmitted orally (through kissing, for example).

'Unusal response to Epstein-Barr virus'

However, the researchers found that people with high genetic risk of schizophrenia and who also presented high levels of Epstein-Barr virus antibibodies had an increased probability to pertain to the schizophrenia group — more than eight times higher, to be precise.

Also, among participants with schizophrenia, around 10 percent had both high levels of antibodies against this type of herpes virus and a higher genetic risk for schizophrenia, compared with only a little over 1 percent of the participants in the control group.

"We found that individuals with schizophrenia had an unusual response to Epstein-Barr virus. This indicated that the prevention and treatment of Epstein-Barr virus might represent an approach for the prevention and treatment of serious psychiatric disorders such as schizophrenia."

Dr. Robert Yolken

The study did not seek to establish cause and effect relationships, but the researchers suggest that preventing infection with the Epstein-Barr virus may be helpful in the context of schizophrenia risk.

However, the United States Food and Drug Administration (FDA) have not yet approved any drugs for the treatment of this type of herpes virus. That said, researchers are currently studying some drugs with therapeutic potential.