Cats are one of the favorite pets of animal lovers and that is why a recent discovery could be bad news for those who want to live with a feline, since a review of studies that analyze the connection between owning and a cat and presenting disorders related to schizophrenia has found that regular contact with this animal could potentially double the risk of a person developing these types of disorders.
The research has been carried out by scientists from The Park Center for Mental Health (Australia) who, however, have highlighted that it is necessary to continue studying this potential relationship. The researchers carried out the analysis of 17 studies published from January 1, 1980 to May 30, 2023, which came from 11 different countries – some of which spanned more than 44 years – and which provided original data on the Cat ownership and schizophrenia-related outcomes.
The results of the work have been published in the journal Schizophrenia and reveal that having a cat was associated with an increased risk of disorders related to schizophrenia. Specifically, they found a more than twofold increase in the odds of developing schizophrenia-related disorders among all individuals exposed to cats.
Childhood exposure to cats and mental problems
Although some studies suggest that exposure to cats during childhood may be associated with an increased risk of developing schizophrenia-related disorders, the exact age or specific period of exposure is not clearly defined in all studies.
One of the studies analyzed, which was from Finland, initially showed higher scores on the perceptual aberration, schizoid, and social anhedonia scales for those children exposed to cats before the age of seven, although they limited their conclusion to perceptual aberration. Another study from the United Kingdom found associations between exposure to cats during childhood (at ages 4 and 10) and greater psychotic experiences at age 13.
The findings suggest that it is necessary to precisely identify the specific period of exposure that could constitute the greatest risk of developing schizophrenia-related disorders associated with exposure to cats during youth. The overall risk trend centers on the interaction between the developing brain and feline exposure.
Toxoplasmosis and risk of schizophrenia
But, of course, being in contact with cats is not the highest risk factor, but there is a causal agent that acts unseen in the environment of these animals and that is probably the real culprit of the problem: Toxoplasma gondii, a parasite that causes toxoplasma infection or toxoplasmosis.
Toxoplasma gondii (T. gondii) is an intracellular protozoan parasite that triggers toxoplasmosis, an infection that is estimated to have affected around 25% of the world’s population at some point in their lives and that is especially dangerous for pregnant women because it can harm the developing fetus and cause everything from abortion to neonatal blindness or subsequent loss of vision, mental disability and seizures.
There is a causal agent that acts unseen in the environment of cats and that is probably the real culprit of the increased risk of schizophrenia: ‘Toxoplasma gondii’
T. gondii infection has previously been linked to neurological alterations and behavioral changes, and some symptoms of schizophrenia can be reversed with antiprotozoal drugs, suggesting that its main cause could have been having previously suffered toxoplasmosis.
In fact, a 2012 meta-analysis of 38 studies, ‘Toxoplasma gondii and other risk factors for schizophrenia’, also published in Schizophrenia Bulletin, found that patients with schizophrenia were almost three times more likely to have antibodies to toxoplasma in their blood, which suggests that this mental pathology was more prevalent in those who had suffered this type of infection.
Toxoplasmosis has also been linked to diseases and behavioral changes in animals that often have negative consequences for their survival. For example, a University of Geneva study published in Cell Reports showed that rats lose their fear of cats when infected with T. gondii, and it has been found that most California sea lions that are distressed or dead people have a toxoplasma infection, one reason we should never flush cat litter down the toilet.
