By Erika Niedowski
The Baltimore Sun
August 20, 2004
Pisces (Feb. 19 - March 20): Governed by Neptune and symbolized by the fish. Compassionate, introspective, artistic. Often dreamy and impractical. May be prone to schizophrenia, epilepsy or bipolar disorder.
It may sound like some kind of new, madcap astrology, but a number of scientists are becoming convinced that our birth month may predispose us to particular diseases later in life.
Studies have shown that schizophrenia is more common among those born in late winter or early spring. Multiple sclerosis is associated with births in April, May and June. And epilepsy occurs more frequently in those with birthdays from December to March.
Clues into causes
Researchers hope the emerging patterns will offer clues into the origins of a range of illnesses that, despite advances in treatment, have no known cause.
"It makes you think differently about disease," said Dr. Emmanuel Mignot, professor of psychiatry and behavioral sciences at Stanford University School of Medicine, who has studied the association between birth month and narcolepsy.
"Most people tend to think that disease is really something that is determined by your genes or what happens just before the disease occurs," he said. "Maybe there are a number of things that can happen well before."
In the latest study, published in the current edition of the journal Neurology, scientists at the National Cancer Institute found that adults born in January and February had the highest risk of brain cancer. Those with birthdays in July and August had the lowest risk.
The paper's lead author, NCI epidemiologist Alina V. Brenner, is the first to offer a caveat: The findings could be the result of chance.
But separate studies in Britain and Norway have identified a similar correlation between birth season and risk of brain tumors in children, with a statistical "excess" of births in winter and a "deficit" in summer.
If the association turns out to be real, Brenner said, it suggests that exposures early in a child's development -- at any point from conception to the first few months after birth -- could have a hand in the genesis of the disease. Though it's not clear what those exposures are, they could include viruses, environmental toxins or even something as seemingly benign as the weather.
Infections may play role
Seasonal birth patterns have been most firmly established in schizophrenia patients. Several years ago, a group of Danish researchers reported that the risk of developing the disorder was highest among those born in February and March and lowest among those with birthdays in August and September.
Dr. E. Fuller Torrey, research psychiatrist at the Uniformed Services University of Health Sciences in Bethesda, Md., has ruled out the possibility that chance alone explains the findings.
"It could be chance if it were one study of 250 people, or a few dozen people here or a few dozen people there," he said. "When you're dealing with a couple hundred thousand people and 200 studies, the chances of it being chance are zero-point-zero. It's remarkably consistent."
The leading explanation implicates a seasonal infection that could be disturbing the child's normal brain development, which may help explain why other central nervous system disorders are also more common in those with winter births.