CBS News reports that new research suggests such a possible link, but doesn't prove a cause-and-effect connection.
More than 60 million people in the United States have the Toxoplasma gondii parasite, but most never experience any symptoms. But in people with a weakened immune system, T. gondii can cause an illness called toxoplasmosis and potentially lead to miscarriages and fetal problems in pregnant women, long-lasting flu-like illness, blindness and even death, CBS News reported.
Previous research had linked T. gondii with schiziophrenia and bipolar disorder, and two recent studies provide further possible evidence of a connection between the parasite and mental illness, the news network said.
In a paper published in the journal Schizophrenia Research, investigators analyzed three previous studies and found that exposure to cats during childhood may be a risk factor for mental disorders late in life, CBS News reported.
"Cat ownership in childhood has now been reported in three studies to be significantly more common in families in which the child is later diagnosed with schizophrenia or another serious mental illness," E. Fuller Torrey, of the Stanley Medical Research Institute, and Dr. Robert Yolken, of Stanley Laboratory of Developmental Neurovirology at the Johns Hopkins University School of Medicine, said in a news release.
In a second paper, researchers analyzed 50 published studies and found a potential link between T. gondii and mental disorders. They saw that people infected with the parasite had a nearly two times increased risk of developing schizophrenia. The researchers also found a possible association between T. gondii and addiction and obsessive-compulsive disorders, CBS News reported.
"In schizophrenia, the evidence of an association with T. gondii is overwhelming," A.L. Sutterland, who's with the Department of Psychiatry at the Academic Medical Centre in Amsterdam, Holland, and colleagues said in a press release, CBS News reported. "These findings may give further clues about how T. gondii infection can possibly [alter] the risk of specific psychiatric disorders."
Their study was published in the journal Acta Psychiatrica Scandinavica.
"Children can be protected by keeping their cat exclusively indoors and always covering the sandbox when not in use," Torrey told CBS News in an email.
Change your cat's litter box daily and avoid feeding cats raw or undercooked meat, the U.S. Centers for Disease Control and Prevention advises. When changing the litter box, it's best to wear disposable gloves and wash hands thoroughly with soap and water afterwards. Pregnant women should not clean litter boxes.