The Flu Connection
Does prenatal exposure to influenza raise the risk of schizophrenia? By
CHRISTINE GORMAN


Monday, Aug. 16, 2004
Doctors still don't know what exactly causes schizophrenia, a
devastating mental illness characterized by extremely disordered
thinking. They're pretty sure that some kind of genetic predisposition
is at work. But they also suspect that environmental triggers -
particularly at critical moments during the brain's development before
birth - play a role. That's why the results of a study published last
week in the Archives of General Psychiatry are so intriguing. For the
first time, researchers have direct evidence that exposure to influenza
in utero is tied to a greater likelihood that an individual will someday
develop schizophrenia.

That doesn't mean that the link between influenza and schizophrenia is
airtight. "It's really important to duplicate these results," says Dr.
Alan Brown, a psychiatrist at the New York State Psychiatric Institute
in New York City, who led the study. But the new findings fit a pattern
that has been emerging since researchers noticed a spike in cases of
schizophrenia among people born in Denmark in 1957 during a major flu
epidemic.

Brown and his colleagues looked at blood-serum samples taken from HMO
patients who were pregnant between 1959 and 1966. Then they zeroed in on
those women whose children later developed schizophrenia. The
researchers discovered that the presence of influenza antibodies - a
sure sign of infection - during the first half of pregnancy correlated
with a threefold greater risk of schizophrenia. There was no correlation
with influenza during the second half of pregnancy.

Why would exposure to influenza during pregnancy increase the risk of
schizophrenia? No one knows. Perhaps the infection somehow damages the
developing brain. Or the reason may have something to do with how
influenza affects the mother's lungs, decreasing the amount of oxygen
that can get to the fetus. But even if the link is real, it would
account for just 14% of schizophrenia cases.

Developing influenza during pregnancy carries its own more immediate
risks and often requires hospitalization. That is why the Centers for
Disease Control and Prevention recommends that all women who are or plan
to be pregnant during flu season get vaccinated starting in the fall. To
avoid infection, it also helps to wash your hands regularly and steer
clear of anyone who's sneezing.

From the Aug. 16, 2004 issue of TIME magazine