Don’t be so quick to throw out your feline companions
I have to admit that as an animal lover, I was biased when I approached this research. A post titled “Cats = Schizophrenia” appeared on my Facebook page and my first though was “Bollocks! What is the science behind this?!” My search began.
Looney premises
I am sure you have all been reading the article circulating on various social media. According to this article, your cat is carrying a bacterium (it is actually a protozoan) that will make you looney, especially if you are in your childhood. But beware of statistics before kicking out your cat to save your sweet little kid from a terrible future! What’s really going on here? Let’s start from scratch.
Many centuries ago, a famous philosopher called Aristotle developed the concept of syllogism: you start from two premises and by combining them, you reach a conclusion. In our case, it is true that cats host the parasite Toxoplasma gondii, which is also frequently found in cat litters (first premise), plus there are some studies suggesting that this organism may cause some cases of schizophrenia (second premise). Therefore, your cat could bring you into contact with Toxoplasma gondii and you could become schizophrenic, right? At least, that is what several media sources concluded. However, this is totally wrong!
Feline frequency
The frequently cited study from Torrey and colleagues from Stanley Medical Research Institute and Stanley Laboratory of Developmental Neurovirology combines the results of three different questionnaires filled out by families with a schizophrenic member. But what do these statistics actually say?
For starters, they found that if you have schizophrenia, there is a 50% chance you had a cat when you were 0-13 years old. This is the first point we should take into account. If you or your kids are above 13, it is too late to worry about it. Studies have not yet said anything about the correlation between owning kitties and having schizophrenia after the age of 13.
On top of that, let’s make a comparison and suppose you got sick four times this year and twice you were wearing a nice blue shirt the day you started not feeling well. Would you conclude that this blue shirt is responsible for your illness? This is a classic case of correlation not necessarily implying causation. Just because two points of data share a relationship does not mean that one causes the other. To the point, just because you had a cat and have schizophrenia does not necessarily mean that the cat is to blame…
Furthermore, how frequent is schizophrenia? On average, it is believed that between 0.5% and 1% of the population is schizophrenic. Taking this percentage into account, this means that between 0.25% and 0.5% people have schizophrenia and a cat (or had one). When taken into the proper context, it sounds significantly less terrifying than “50% of schizophrenics had cats”, right? Statistics can be easily used to misrepresent a situation. After all, there are “lies, damned lies and statistics”. In addition, in families without anyone suffering from schizophrenia approximately 41% had a cat. This makes for a high amount of mentally sane individuals owning a cat.
Finally, a study from 2012 concluded that “cat ownership does not strongly increase the risk of T. gondii infection.”
Kitty guilt
Do not get me wrong. This study is important and vital for further investigation of the relationship between schizophrenia and Toxoplasma. As the authors suggest, it may be the combination of the parasite with some other cat features, e.g. allergies, that causes the mental disease. Despite this, various pop science articles on the research substitute the link found between schizophrenia and owning a cat in childhood with a cause-effect relation.
Let’s sum it up, Aristotelian style. Premise one: if you are schizophrenic, I can guess with 50% accuracy whether you had a cat in your childhood or not. Premise two: the fact that you owned a cat does not necessarily mean that you had higher chances of getting infected by the terrible protozoan. If both premises are correct, then it follows that your cat is quite likely to be innocent.
Now that you’ve gotten a clearer picture, do you feel sorry and guilty for accusing your fluffy little rascal? Consider for example, how animal-assisted therapy for children has become increasingly important. Your cat, or pets in general, may actually help your kids in difficult times. Among others, two recent studies just showed how pets can ease recovery after surgery (Calcaterra et al., 2015) or influence positive social and relational behaviour (Harper, 2015.)
What do you think? Does your feline friend deserve a treat now?
References:
Fuller Torrey E, Simmons W, & Yolken RH (2015). Is childhood cat ownership a risk factor for schizophrenia later in life? Schizophrenia research, 165 (1), 1-2 PMID: 25892720
Calcaterra V, Veggiotti P, Palestrini C, De Giorgis V, Raschetti R, Tumminelli M, Mencherini S, Papotti F, Klersy C, Albertini R, Ostuni S, & Pelizzo G (2015). Post-operative benefits of animal-assisted therapy in pediatric surgery: a randomised study. PloS one, 10 (6) PMID: 26039494
Harper, C. J. (2015) An exploration into the impact of animals as a therapeutic adjunct in education for children with behaviour, emotional and social difficulties: A biophilic philosophy for education. PhD, University of the West of England.
Image: Louis Wain was an artist primarily known for his drawings of cats. In his later years he may have suffered from schizophrenia, which some psychiatrists say can be seen in his work.
cat, cats, schizophrenia, statistics, mental, psychiatry, science, methodology
