Scientists have identified a piece of a virus in nerve tissue of schizophrenia patients, a finding that opens the possibility of someday helping these people with antiviral drugs.
The Johns Hopkins University researchers say it is the first time that a portion of a virus has been found in either the cerebrospinal fluid or brain tissue of a small group of newly diagnosed schizophrenic patients — strong evidence the virus might play a role in the onset of the disease in these patients.
Virus Piece in Small Percentage of Schizophrenics
In a study of 35 schizophrenics, the investigators found the molecular footprint of the virus, or a piece of its ribonucleic acid or RNA, in about 30 percent of the patients with acute schizophrenia and 7 percent of the people with the chronic form of the disease.
The RNA was not found in the brains or cerebrospinal fluid of 12 people who did not have the disease.
“While a low level of retrovirus expression occurs in most human tissues, we found an unexpectedly high level of expression in cerebrospinal fluids from individuals who’d had a recent onset of schizophrenia,” says Dr. Robert Yolken, director of the Stanley Division of Developmental Neurovirology at Johns Hopkins and lead author of the research, which appears in the current issue of Proceedings of the National Academy of Sciences.
Characterized by hallucinations and distorted perceptions of reality, schizophrenia is a devastating psychiatric illness that affects one in 100 people in the United States and results in the annual expenditure of $65 billion in health care and related costs.
Some people have one psychotic episode, while others have many episodes in a lifetime, leading relatively normal lives during the interim period. But people with chronic schizophrenia, or those with a continuing and recurring pattern of illness, do not fully recover normal functioning and require long-term treatment with a variety of medications.
There is no single cause of schizophrenia, and like other diseases, it results from an interaction of genetic, behavioral and other factors.
Endogenous Virus Activated Somehow
The piece of the virus was created, the researchers say, by the activation of an endogenous retrovirus, called HERV-W, in these patients. Unlike HIV and other retroviruses, endogenous retroviruses are a part of the human genetic blueprint, having become part of the human genome millions of years ago.
What causes the activation of the virus is unknown. If the RNA is infectious also is unknown.
Yolken says his study supports a retroviral link to schizophrenia in some percentage of patients and could arise from a two-hit process. The first hit probably occurs around birth, when infection by an outside retrovirus leads to insertion in the human genome or the rearrangement of retroviruses already in the genome.
Later in life, he says, something triggers the existing retroviruses to become active and the person starts to display symptoms. That something could be due to other genes the person has or something else in the environment.
“While our report does not explain why the retrovirus becomes active in the first place, it presents clues as to what might happen when it does become active,” says Yolken. “Our ultimate hope is that we can interfere with the retrovirus by preventing it from becoming active. If we can do that, it may give doctors another method of treating schizophrenia.”
Other Genes Probably Play a Role