According to an analysis of 17 studies, owning a cat as a pet may double a person’s risk of developing schizophrenia-related conditions.
Psychiatrist John McGrath and colleagues at the Queensland Center for Mental Health Research in Australia looked at papers published over the past 44 years in 11 countries, including the US and Britain.
Their 2023 study found that “there is a significant positive association between broadly defined cat ownership and an increased risk of schizophrenia-related disorders.”
“More high-quality studies are needed in this area,” the authors emphasize in their published paper.
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The idea that cat ownership could be linked to the risk of schizophrenia was proposed in a 1995 study in which exposure to a parasite Toxoplasma gondii Suggested as a reason. But research so far has revealed mixed findings.
Studies have shown that being around cats during childhood may make a person more likely to develop schizophrenia; However, not all research has found any association.
Some papers also link cat exposure to higher scores on a scale measuring schizophrenia-related symptoms – which affect a person’s thoughts, feelings and behaviors – and psychotic-like experiences, but again, other studies do not show this connection.
To get a clear picture, McGrath and his team say a thorough review and analysis of all the research on these topics is needed.
T. gondii It is a mostly harmless parasite that can spread through undercooked meat or contaminated water.
This disease can also be spread through the bite of an infected cat or cat feces. T. gondii It can also be spread through the bite of an infected cat or through cat feces.
Estimates suggest that T. gondii Infects about 40 million people in the US, usually without any symptoms. Meanwhile, researchers continue to discover even more strange effects of the infection.
Once inside our body, T. gondii Can infiltrate the central nervous system and affect neurotransmitters. The parasite has been linked to personality changes, the emergence of psychotic symptoms, and some neurological disorders, including schizophrenia.
However, does not prove a link T. gondii The reason for these changes is that the parasite passed from cat to human.
“After adjusting for covariates, we found that individuals exposed to cats were almost twice as likely to develop schizophrenia,” the Australian team writes.
There are some important things to keep in mind here, like the fact that 15 of the 17 studies were case-control studies.
This type of research cannot show cause and effect, and it often does not take into account factors that may influence both exposure and outcome.
The researchers also highlight the low quality of many of the studies examined.
Results were inconsistent across studies, but the high-quality results suggested that the associations in the unadjusted models may be due to factors that could have influenced the results.
One study found no significant association between owning a cat before the age of 13 and later developing schizophrenia, but it did identify a significant link when limiting cat ownership to a specific period (9 to 12 years). This inconsistency suggests that the critical window for cat performance is not well defined.
A study in the US, involving 354 psychology students, found no association between cat ownership and schizotypy scores. However, people who were bitten by a cat had higher scores than people who were not bitten by a cat.
Another study, which included people with and without mental disorders, discovered an association between cat bites and higher scores on tests measuring specific psychological experiences. But he suggested other pathogens, such as Pasteurella multocidaInstead it may be responsible.
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Before we can make any solid explanations, the researchers reiterate that we need better and broader research.
The authors concluded, “Our review provides support for an association between cat ownership and schizophrenia-related disorders.”
“More high-quality studies based on larger, representative samples are needed to better understand cat ownership as a candidate risk-modifying factor for mental disorders.”
The research was published in Schizophrenia Bulletin.
An earlier version of this article was published in December 2023.