Mental illness clues
Ian Lipkin thinks germs can trigger mental illness.
The Columbia University neurologist acknowledges his theory is provocative but, he points outs, it could explain much about the ailments that cripple millions of Americans.
Scientists already know that some people have an inherited susceptibility to mental illnesses. Yet not everyone with this genetic predisposition actually gets sick. Perhaps something in their environment causes some people to become debilitated, believes Lipkin, a researcher in the School of Public Health. Infections that occur in the womb, or in infancy, may be the missing puzzle piece, he believes.
Mental illness is not contagious, he adds, but the injury done to fetuses’ or infants’ developing brains by infections may make them more susceptible to such neurological ills as schizophrenia, depression, autism, Parkinson’s disease, multiple sclerosis and even the mental decline that can accompany aging.
“We know a mother’s use of alcohol, tobacco and cocaine can harm a developing fetus,” says Lipkin. “It’s also plausible that maternal infections during a period of vulnerability in the nervous system’s development can damage a gestating infant.”
This notion is controversial, says Dr. Lori L. Altshuler, director of the mood disorders research program at UCLA.
“Some scientists believe it is plausible that infections might be associated with an underlying vulnerability to developing a psychiatric illness,” Altshuler says. “But many are skeptical.”
However, a growing body of scientific evidence is lending credence to the notion that pathogens can spark neurological illnesses.
Viruses such as West Nile can cause encephalitis, for instance, while the bacterial infection toxoplasmosis has been linked to schizophrenia. Studies also have revealed that the Borna disease virus, which causes encephalitis and behavioral disturbances in horses and other animals, is present in nearly everyone with schizophrenia or depression, yet in only one out of three healthy adults.
The presence of the virus doesn’t automatically mean it’s the cause of these mental illnesses, says Lipkin, who was the first to isolate the Borna virus from human brain tissue, and was head of the lab that deciphered the virus’ genome. The results of a large-scale study, due in December, may yield more definitive evidence. Lipkin, and researchers at UC Irvine and UCLA, collected tissue specimens from more than 2,100 patients with schizophrenia, bipolar disorder and major depressive disorder, looking for telltale traces of Borna disease virus.
Even if the study proves there is a link, however, are microbes the culprits -- or are they just innocent bystanders?
Perhaps it’s not the bugs themselves that are causing all the trouble, says Lipkin, but the chemicals the mother’s immune system releases to repel these invaders. In one recent experiment, for instance, mice in utero were exposed to cytokines, which are proteins the immune system dispatches to kill germs. After birth, the mice exhibited marked behavioral abnormalities. “The results were striking,” Lipkin says.
Still, much more research needs to be done. But if infections do turn out to be a cause of some mental illnesses, many seemingly intractable psychiatric disorders might be tamed with antivirals, antibiotics, vaccines or anti-inflammatory drugs to dampen the immune response.
“The brain continues to grow after birth,” Lipkin says. “If we can identify individuals who are at risk, we can intervene early and find ways to enrich their lives, and thereby prevent these debilitating ills.”
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Infections and neurological disorders
To firmly prove a link between microbes and neurological disorders, scientists need to study a large group of people -- and discover the common factors in those who develop such problems.
Neurologist Ian Lipkin and his team have initiated such a study. It eventually will track the pregnancies of 100,000 Norwegian women enrolled in the Scandinavian nation’s medical birth registry. Lipkin chose Norway because pregnant women there are closely monitored to prevent birth defects. Every woman who gets pregnant is part of the registry.
The research team plans to follow these women through childbirth and beyond to determine if maternal infections, toxins or stress spark the development in their children of such neurological disorders as attention deficit hyperactivity disorder, autism, learning disabilities and mental illness.
“It’ll give us an unprecedented look at what happens during pregnancy and in the postpartum environment,” Lipkin says.
