Virus Provides a Clue to the Cause of Schizophrenia
Precisely when the retrovirus is activated, and the exact connection between activation and symptoms of schizophrenia is unknown, the authors say.
It may be activated when the fetus is in the womb by a winter flu or virus caught by a pregnant mother, causing an immediate infection at a critical time when brain cells are forming. Or the reactivated virus may lie in wait for a decade or more before it blooms in the presence of yet another infection in early adolescence or adulthood -- just the time when many patients with schizophrenia first experience symptoms.
"Many of us have become impressed with the realization that infectious agents can get in the central nervous system and sit there for 15 years before they can become active," another author E. Fuller Torrey, MD, tells WebMD. He is director of the Stanley Foundation Research Programs, which helped fund the study.
Both researchers are quick to point out that not all schizophrenia is caused by infection. "My feeling is that schizophrenia is a mixture of diseases, so it is extremely unlikely that either a virus or genes will explain all the cases," Yolken says. "We believe that perhaps 30% of cases may be related to infection."
But he says the findings suggest that doctors may someday be able to treat individuals who are at risk for schizophrenia -- based on their family history or early developmental signs -- with antiviral therapies to keep the retrovirus from becoming active.
Because herpes viruses are known to directly activate retroviruses, Yolken hopes to conduct studies using common antiherpes medications in acute patients to determine if they can improve symptoms of schizophrenia. If the drugs work, they could be used in at-risk patients to forestall retrovirus activation, and thereby prevent schizophrenia, he says.