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Leave, kitty, kitty, kitty.

Jun 10, 2015 02:00PM ● By Cate Reynolds
Some truly shocking, and scary, reports recently surfaced about the relationship between a cat-carried parasite and the development of schizophrenia in humans. The connection is T. gondii, the most common parasite found in developed countries, according to an article in Schizophrenia Bulletin. The parasite can infect any warm-blooded creature and it’s carried by cats. The CDC estimates that more than 60 million people in the U.S. may have it—though most never become symptomatic.

However, some organizations have long been examining T. gondii and its possible effects—the Stanley Medical Research Institute (SMRI) for instance. This Chevy Chase-based nonprofit supports research on the cause of, and treatments for, schizophrenia and bipolar disorder. (Since it began in 1989, SMRI has supported more than $550 million in research in more than 30 countries.)

SMRI has undertaken extensive research on infectious agents as one of the possible causes of schizophrenia. Among the infectious agents that appear most promising is Toxoplasma gondii, a protozoan parasite that causes toxoplasmosis and is carried by cats and other felines. Until recently, toxoplasmosis was thought to be a problem only for pregnant women who, if they became infected with T. gondii during their pregnancy, risked having the organism cause damage to the growing fetus. This is why pregnant women are advised to not change the litter in the cat litter box. Infection with T. gondii in other adults and children was thought to be either asymptomatic or to cause an influenza-like or mononucleosis-like syndrome. It now seems possible that T. gondii may be associated with some cases of schizophrenia and perhaps other psychiatric syndromes.

According to SMRI, “Schizophrenia is a brain disease that begins in young adults, typically between the ages of 16 and 30, and is characterized by some combination of auditory hallucinations (hearing voices), delusions, flattened affect, disordered thought patterns, bizarre behavior, and social withdrawal. Schizophrenia affects approximately 1 percent of the adult population and in most cases is a lifelong disease with remissions and exacerbations. It is also a very expensive disease. Conservative estimates place the cost of schizophrenia in the United States at more than $40 billion a year.”

The most recent study compared two previous studies—one that found a link between childhood cat ownership and the development of schizophrenia later in life, and an unpublished survey on mental health from 1982, 10 years before any data on cat ownership and mental illness had been published. Results of the analysis indicted that cat exposure in childhood may be a risk factor for developing mental disorders. Yikes.

A second study from Amsterdam analyzed the findings from 50 published studies to confirm that T. gondii infections are associated with mental disorders. Individuals infected were almost twice as likely to develop schizophrenia; as well as demonstrating an association with addiction and obsessive-compulsive disorder. “In schizophrenia, the evidence of an association with T. gondii is overwhelming,” the study authors said.

--Sarah Hagerty
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