If the findings hold up under scrutiny, they could lead to breakthroughs in both preventing and treating schizophrenia, says study author Stephen L. Buka, an associate professor at the Harvard School of Public Health.
While mental illnesses like depression and anxiety get more public attention, schizophrenia affects an estimated one in every 100 people, or more than 2.5 million Americans.
Though schizophrenia patients often are thought to have multiple personalities, the disease has a wide variety of symptoms. Victims often suffer from delusions (such as beliefs that they are being monitored through technology), hallucinations (hearing voices) and incoherent speech.
"While we've got all these medications that are much better than 10 years ago, it's still a devastating disease, and some think it's the most devastating of all," says Dr. Dave M. Davis, director of the Piedmont Psychiatric Clinic in Atlanta. "It hits people typically in their late adolescence, and they're disabled for life."
No one knows what makes people schizophrenic. "A lot of people feel it's purely genetic, and others think something in the environment helps it to develop," Buka says.
The Harvard study attempted to test the long-held suspicion that viral illnesses in a pregnant woman causes the disease by affecting the brain of a fetus.
The researchers used 30-year old blood samples from about 4,000 pregnant women. The blood tests were still around, and so were many of the children. The odds were that 40 children, or 1 percent, would have schizophrenia. The actual number turned out to be 27, Buka says.
At the time the samples were taken, the women were being tested for immune-system responses to several infectious viral diseases, including herpes simplex, chlamydia and a type of human papilloma virus. Of all the diseases, only herpes simplex 2, which is transmitted sexually, appears to have affected the mothers of the schizophrenic subjects more often than the mothers of other subjects born around the same time.
The study's findings appear in the November 2001 issue of the
Archives of General Psychiatry.
An estimated one of every five Americans is infected with herpes simplex 2, and the rate has gone up in recent decades, Buka says.
How the herpes virus in a pregnant woman could affect the brains of their fetuses is not entirely clear, but doctors know that certain illnesses in pregnant women can cause a variety of diseases, such as mental retardation, cerebral palsy, epilepsy and deafness, Buka says.
Davis says one theory suggests that the herpes virus interferes with brain development. "During the fetal period, brains are growing at a very rapid rate," and a virus "could disrupt all kinds of processes -- how the cells hook up with one another, how the neurotransmitters work within the synapses [to carry brain signals]. The virus could act on many different levels."
Buka says the mother's own body may be at fault. "The immune response is out there killing the virus, and it can also be attacking the nervous system of the fetus."
If herpes does cause schizophrenia, it could be good news. That's the one [virus] that's easiest to do something about," Buka says.
While herpes is not curable, drug treatments can keep the disease in check, and they won't harm the fetus, he says.
Research like the Harvard study also could make obstetricians more alert to the risks posed by illnesses in pregnant women, and that could lead to better and earlier treatment, Davis says.
What To Do
Learn about the many symptoms of schizophrenia in this report from the U.S. Surgeon General's office.