Cats are one of the most popular pets in the world, but they may also pose a hidden danger to their owners. A new study suggests that cat ownership in childhood is linked to a higher risk of developing schizophrenia and other mental disorders later in life, possibly due to a common parasite found in cats.
The parasite, called Toxoplasma gondii (T. gondii), is the cause of a disease known as toxoplasmosis. It can infect humans through contact with cat feces or contaminated food or water. According to the Centers for Disease Control and Prevention (CDC), more than 60 million people in the US are infected with the parasite, though most of them are not aware of it.
“People with a healthy immune system often stave off T. gondii infection, so it does not present any symptoms,” a spokesperson from the CDC said. However, pregnant women and people with weakened immune systems are more vulnerable to infection and may experience serious complications, such as blindness or even death.
Previous studies have also linked T. gondii infection to a greater risk of mental disorders, such as schizophrenia, bipolar disorder, and depression. In 2014, a study claimed that the parasite is responsible for around a fifth of schizophrenia cases.
Now, new research provides further evidence of this association. The study, led by Dr. Robert H. Yolken, of the Stanley Laboratory of Developmental Neurovirology at Johns Hopkins University School of Medicine in Baltimore, MD, analyzed the results of two previous studies and a questionnaire conducted in 1982 by the National Alliance for the Mentally Ill (NAMI).
The NAMI questionnaire, which was done before any data was published on cat ownership and mental illness, revealed that around 50% of individuals who had a cat as a family pet during childhood were diagnosed with schizophrenia or other mental illnesses later in life, compared with 42% who did not have a cat during childhood.
The researchers say that the questionnaire produced similar results to those of the two previous studies, suggesting that “cat ownership in childhood is significantly more common in families in which the child later becomes seriously mentally ill”.
“If true, an explanatory mechanism may be T. gondii,” Dr. Yolken said. This implies that the parasite could play a role in the development of these mental illnesses. However, it is important to note that this research only shows a correlation, not a causal relationship.
While the research suggests a potential link between cat ownership and the risk of developing mental illnesses, it is important to remember that correlation does not imply causation. Owning a cat comes with plenty of benefits. According to a 2008 study from researchers at the University of Minnesota’s Stroke Institute, cat owners are 30 percent less likely to die of a heart attack. Plus, spending time with pets eases feelings of loneliness, according to the CDC. Further research is needed to fully understand the relationship between cat ownership, T. gondii, and mental health. In the meantime, it is recommended to practice good hygiene when handling cats and their litter boxes to reduce the risk of T. gondii infection.
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– Do Cats Cause Schizophrenia? | Britannica