Study: Schizophrenia linked to date, place of birth

February 25, 1999
Web posted at: 6:45 a.m. EST (1145 GMT)

From Medical Correspondent Rhonda Rowland

BOSTON (CNN) -- Where and when children are born may play a role in whether they develop schizophrenia in later life, according to the results of a new study published in the New England Journal of Medicine.

Danish researchers found that children born in an urban or suburban area, rather than a rural area, and those born in February or March had an increased risk of schizophrenia, a puzzling and disabling brain disorder that runs in families.

The new research suggests that environmental factors, as well as genetics, may play a role in schizophrenia.

"I think the important finding from this study is, yes genes are important, but environmental factors are at least as important," said Dr. E. Fuller Torrey of the Stanley Foundation Research Programs. "And we probably haven't paid enough attention to them."

In the study, researchers tracked almost 2 million people in Denmark. They theorize that living in cities and having winter birthdays may expose people to infectious agents that could be involved in the development of the disorder.

"Our own research has been on viruses, and we think they are involved in the cause of many, if not most, cases of schizophrenia," Torrey said.

Schizophrenia is believed to be triggered by some event in the brain that occurs between the second trimester of pregnancy and early adolescence. It affects about 2 million people in the United States and costs the country about $32 billion a year.