HQ Team
December 11, 2023: Australian researchers reveal that having a cat can potentially double a person’s risk of schizophrenia-related disorders transmitted through a parasite found in the animals.
“We found an association between broadly defined cat ownership and increased odds of developing schizophrenia-related disorders,” psychiatrist John McGrath, from the Queensland Centre for Mental Health Research, wrote in Schizophrenia Bulletin.
Previous studies have indicated that cat ownership could be linked to schizophrenia risk due to exposure to a parasite called Toxoplasma gondii.
Other researchers and scientists have linked cat exposure to higher scores on scales that measure traits related to schizophrenia – which affects a person’s thoughts, feelings, and behaviours – and psychotic-like experiences.
Transmission
Toxoplasma gondii is a mostly harmless parasite that can be transmitted through undercooked meat or contaminated water. A bite from an infected cat or the faeces of an infected cat can also transmit the parasite.
It is estimated that around 40 million people in the US may be infected, usually without any symptoms. Meanwhile, researchers keep finding more strange effects that infections may have.
In humans, the parasite can infiltrate the central nervous system and influence neurotransmitters. The parasite has been linked to personality changes, the emergence of psychotic symptoms, and some neurological disorders, including schizophrenia.
Australian researchers analysed 17 studies published during the last 44 years, from 11 countries including the US and the UK. The new analysis of 17 studies found “a significant positive association between broadly defined cat ownership and an increased risk of schizophrenia-related disorders.”
Twice the odds
McGrath and his team found “a significant positive association between broadly defined cat ownership and an increased risk of schizophrenia-related disorders.”
“After adjusting for covariates, we found that individuals exposed to cats had approximately twice the odds of developing schizophrenia,” McGrath wrote.
However, a link doesn’t prove that the parasite caused these changes or that the parasite was passed on to a human from a cat.
The research has its drawbacks. Fifteen of the 17 studies were case-control studies and this kind of research cannot prove cause and effect.
It also often does not look at things that might have affected both the exposure and the outcome.
“In conclusion, our review provides support for an association between cat ownership and schizophrenia-related disorders,” the authors wrote.
‘Need for more studies’
“There is a need for more high-quality studies, based on large, representative samples to better understand cat ownership as a candidate risk-modifying factor for mental disorders.”
The Toxoplasma parasite can persist for long periods in the bodies of humans (and other animals), possibly even for a lifetime.
Of those who are infected, however, very few have symptoms because a healthy person’s immune system usually keeps the parasite from causing illness.
Pregnant women and individuals who have compromised immune systems should be cautious as for them, an infection could cause serious health problems, according to the Centers for Disease and Prevention Control.
