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Study: Cats drive some people crazyJanuary 26, 2001 BY PHIL SURGUY Researchers have found evidence that cats really do drive people crazy. Dr. Robert Yolken, a pediatrician at Johns Hopkins University in Baltimore, and Dr. Fuller Torrey, director of the Stanley Foundation Research Programs in Bethesda, Md., believe schizophrenia and possibly bipolar disorders such as manic depressive illness are caused by an infectious agent acting on the brain. And one of their prime suspects is a parasite called toxoplasma gondii, which is spread to humans by cat feces. The parasite can cause toxoplasmosis, a generally mild illness. Most people's immune systems will cut short a T. gondii invasion without symptoms. However, pregnant women who contract the parasite can transmit it to the fetus, with devastating effects on brain development. Torrey and Yolken believe the parasite can enter the fetal brain, lie dormant for 15 to 30 years, then activate and induce schizophrenia. But Torrey cautions: "Don't get rid of your cats yet. We haven't proven anything." Pathologists at the Stanley Foundation Brain Bank in Bethesda are searching for signs of T. gondii infection in the brains of people who suffered schizophrenia, bipolar disorder or severe depression. |
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They are about to begin clinical trials in which schizophrenics will be given drugs normally used to treat the infection. Torrey and Yolken began to suspect a link between schizophrenia and the cat-borne infection because people with the disease are more likely to have been born in late winter or early spring than the general population--and cats stay inside and use their litter boxes more in winter. They also noted that bipolar disorder and schizophrenia were relatively rare in Europe until the late 19th century, when cats became popular as pets. Also, they found in one test that children who went on to develop schizophrenia were more likely to come from homes with cats. Blood samples taken between 1959 and 1966 from 2,500 pregnant women in Providence, R.I., revealed that the mothers of children who later exhibited psychoses were more than four times more likely to have antibodies to toxoplasmosis, one of the diseases that can have schizophrenia-like symptoms. Torrey and Yolken also are considering other possible agents, particularly the herpes viruses, which can lie dormant for long periods and have symptoms that wax and wane like those of schizophrenia. "They all have a strong affinity for brain tissue," Torrey says. He says the herpes virus HSV1 "in particular has a strong affinity for the same part of the brain that we're looking at in schizophrenia." In one of the upcoming clinical trials, schizophrenia patients will be given acyclovir, an anti-viral drug used to treat herpes. In the other trial, patients will be given antibiotics used in the treatment of toxoplasmosis. Dr. Mary Seeman, a University of Toronto psychiatry professor, says Torrey's ideas are "just as plausible as any other theory of schizophrenia, since the causes are completely unknown, other than that genes are involved."
National Post |