By Wayne Persky
Founder and President of the Microscopic Colitis Foundation
According to a recent online Medical Xpress article, having a cat more than doubles the risk of kids developing schizophrenia later in life (Jackson, 2023, December 11).1 Research published back in 2012, titled, "Toxoplasma gondii and Other Risk Factors for Schizophrenia", and published in "Schizophrenia Bulletin" showed that schizophrenia patients were nearly 3 times more likely to have toxoplasma antibodies in their blood (meaning that previous toxoplasma infections were prevalent among schizophrenia patients) (Torrey, Bartko, and Yolken, 2012).2
An updated research study looked at data from various databases, and considered data from 1,915 studies published between January 1, 1980 and May 30, 2023. The researchers selected 17 of those studies, from 11 different countries, to derive updated data (McGrath, Lim, , and Saha, 2023).i They determined that anyone exposed to cats had more than double the odds of developing schizophrenia (at some point in their life), when compared with individuals who were not exposed to cats. This study was also published in the Schizophrenia Bulletin (McGrath, Lim, , and Saha, 2023).
In addition to the behavioral changes mentioned in my previous article about toxoplasmosis, the disease is a leading cause of blindness in newborns, and it can cause later vision loss, mental disabilities, and seizures. A mortality risk exists for anyone who has a severely weakened immune system, unless they take a drug daily, to eliminate that risk. These are the primary reasons why kitty litter bags carry a warning label for pregnant women to avoid contact with cat feces.
Why do cats alone enable toxoplasma gondii reproduction?
The Medical Xpress article cited above (Jackson, 2023, December 11) reveals the reason why cat intestines provide a unique environment that allows toxoplasma gondii to reproduce, even though the parasite cannot reproduce in the intestines of any other species. Toxoplasma gondii requires a high level of linoleic acid in order to be able to reproduce.
Delta-6-desaturase enzyme metabolizes linoleic acid.
All other mammals (other than cats) produce a digestive enzyme known as delta-6-desaturase, and their intestines contain enough of this enzyme to prevent the parasite from being able to reproduce. The primary function of delta-6-desaturase is to convert both omega-6 and omega-3 fatty acids (α-linolenic [n-3] and linoleic acid [n-6]) to their respective metabolites. That means that it converts linoleic acid to oleic acid. Because cats are not capable of producing delta-6-desaturase, their intestines are loaded with linoleic acid.
Unfortunately, cats become contaminated when they defecate.
Cats' tidy habit of digging a hole in which to defecate, and then covering it afterwards, means that their paws, including the fur between their toes, can become contaminated with the oocytes (equivalent of the parasite's eggs), and they can subsequently spread them all over their body while grooming, or all over the floor, countertops, or anywhere else where they place their paws, or rub their fur, afterward. As mentioned in the article that I posted previously, the best way to protect yourself, your family, and your pet cat from infection, is to never let your cat outside the house, so that it never becomes infected.
Anyone who desires to study the association of toxoplasmosis with schizophrenia in more detail can find extensive information in the study at the following link:
https://advances.umw.edu.pl/pdf/2017/26/6/1031.pdf
References
1. Jackson, J. (2023, December 11). Kids with cats have more than double the risk of developing schizophrenia, researchers find. Medical Xpress, Retrieved from https://medicalxpress.com/news/2023-12-kids-cats-schizophrenia.html
2. Torrey, E. F., Bartko, J. J., and Yolken, R. H. (2012). Toxoplasma gondii and Other Risk Factors for Schizophrenia: An Update. Schizophrenia Bulletin, University Of Maryland School of Medicine, 38(3), pp 642–647. Retrieved from https://academic.oup.com/schizophreniabulletin/article/38/3/642/1867672?login=false#
3. McGrath, J. J., Lim, C. C. W., and Saha, S. (2023). Cat Ownership and Schizophrenia-Related Disorders and Psychotic-Like Experiences: A Systematic Review and Meta-Analysis. Schizophrenia Bulletin, University Of Maryland School of Medicine, sbad168. Retrieved from https://academic.oup.com/schizophreniabulletin/advance-article-abstract/doi/10.1093/schbul/sbad168/7458104?redirectedFrom=fulltext&login=false#
In addition to the behavioral changes mentioned in my previous article about toxoplasmosis, the disease is a leading cause of blindness in newborns, and it can cause later vision loss, mental disabilities, and seizures. A mortality risk exists for anyone who has a severely weakened immune system, unless they take a drug daily, to eliminate that risk. These are the primary reasons why kitty litter bags carry a warning label for pregnant women to avoid contact with cat feces.
Why do cats alone enable toxoplasma gondii reproduction?
The Medical Xpress article cited above (Jackson, 2023, December 11) reveals the reason why cat intestines provide a unique environment that allows toxoplasma gondii to reproduce, even though the parasite cannot reproduce in the intestines of any other species. Toxoplasma gondii requires a high level of linoleic acid in order to be able to reproduce.
Delta-6-desaturase enzyme metabolizes linoleic acid.
All other mammals (other than cats) produce a digestive enzyme known as delta-6-desaturase, and their intestines contain enough of this enzyme to prevent the parasite from being able to reproduce. The primary function of delta-6-desaturase is to convert both omega-6 and omega-3 fatty acids (α-linolenic [n-3] and linoleic acid [n-6]) to their respective metabolites. That means that it converts linoleic acid to oleic acid. Because cats are not capable of producing delta-6-desaturase, their intestines are loaded with linoleic acid.
Unfortunately, cats become contaminated when they defecate.
Cats' tidy habit of digging a hole in which to defecate, and then covering it afterwards, means that their paws, including the fur between their toes, can become contaminated with the oocytes (equivalent of the parasite's eggs), and they can subsequently spread them all over their body while grooming, or all over the floor, countertops, or anywhere else where they place their paws, or rub their fur, afterward. As mentioned in the article that I posted previously, the best way to protect yourself, your family, and your pet cat from infection, is to never let your cat outside the house, so that it never becomes infected.
Anyone who desires to study the association of toxoplasmosis with schizophrenia in more detail can find extensive information in the study at the following link:
https://advances.umw.edu.pl/pdf/2017/26/6/1031.pdf
References
1. Jackson, J. (2023, December 11). Kids with cats have more than double the risk of developing schizophrenia, researchers find. Medical Xpress, Retrieved from https://medicalxpress.com/news/2023-12-kids-cats-schizophrenia.html
2. Torrey, E. F., Bartko, J. J., and Yolken, R. H. (2012). Toxoplasma gondii and Other Risk Factors for Schizophrenia: An Update. Schizophrenia Bulletin, University Of Maryland School of Medicine, 38(3), pp 642–647. Retrieved from https://academic.oup.com/schizophreniabulletin/article/38/3/642/1867672?login=false#
3. McGrath, J. J., Lim, C. C. W., and Saha, S. (2023). Cat Ownership and Schizophrenia-Related Disorders and Psychotic-Like Experiences: A Systematic Review and Meta-Analysis. Schizophrenia Bulletin, University Of Maryland School of Medicine, sbad168. Retrieved from https://academic.oup.com/schizophreniabulletin/advance-article-abstract/doi/10.1093/schbul/sbad168/7458104?redirectedFrom=fulltext&login=false#
