A virus may play an important role in the onset of schizophrenia, a devastating mental disorder that affects 1% of the population, according to a report in the 10 April issue of the Proceedings of the National Academy of Sciences. The results provide the first strong biological evidence for the controversial idea that infectious agents may contribute to schizophrenia. The findings also raise the possibility that antiviral drugs might eventually be used to stop the disease.
Schizophrenia clearly has a strong genetic component. But researchers have also discovered that some events early in life, such as maternal malnutrition, perinatal infections, and birth in winter or spring are risk factors too. Virologist Robert Yolken of Johns Hopkins Medical School in Baltimore and psychiatrist E. Fuller Torrey of the National Alliance for the Mentally Ill Research Institute in Bethesda, Maryland, have long argued that each of these factors may stimulate infectious agents that could provoke individuals to develop schizophrenia as adults. But so far, hard evidence has been lacking.
Along with colleagues at the University of Heidelberg, Yolken and Torrey looked for evidence in cerebrospinal fluid, which bathes and protects the brain. They sampled fluid from 20 patients with a long history of schizophrenia, 35 individuals that had recently developed the disorder, and a number of different control groups. They searched the fluid for traces of RNA indicating the presence of different classes of retroviruses, RNA viruses that, like HIV, copy their sequence into the genome of infected organisms.
Of individuals with recent-onset schizophrenia, 29% exhibited signs of a particular family of retroviruses known as Human Endogenous Retrovirus W (HERV-W), compared with none of the control patients. The same pattern was found in brain tissue of deceased schizophrenics and healthy individuals. HERV-W lies dormant as a stretch of DNA in the genome of all humans; Yolken and Torrey suggest that it might somehow be activated in schizophrenics. They think the HERV-W may help the disease progress early in its course, because only 5% of the chronic schizophrenics are infected. Alternatively, they say, it might be new infection by viruses similar to HERV-W that helps lead to schizophrenia.
So far, the evidence for the role of the virus is "only modest," says University of Virginia psychologist Irving Gottesman. He notes that the infection may simply be an effect of the disease. But if schizophrenia is really caused by a dormant virus that "wakes up," what sets the process in motion, wonders Gottesman. "If they have uncovered the trigger," he asks, "then what triggers the trigger?"
--JOSH GEWOLB
Related sites
The Yolken Laboratory
Profile of E. Fuller Torrey in Lingua Franca
