Kids with cats have double the risk of developing schizophrenia | Hacker News Reader

Kids with cats have double the risk of developing schizophrenia

medicalxpress.com

133 pointswglb101 comments

That's not what the source meta-analysis[0] says: "Our findings support an association between cat exposure and an increased risk of broadly defined schizophrenia-related disorders; however, the findings related to PLE as an outcome are mixed. There is a need for more high-quality studies in this field." (DOI: 10.1093/schbul/sbad168 linked at the bottom of the editorial)

[0]: https://academic.oup.com/schizophreniabulletin/advance-artic...

The more accurate title would say "schizophrenia-related disorders". Since cat-related schizoform disorders may be clinically distinct, this could be a useful distinction.

On the contrary the epidemiological interpretation of the study's conclusion would be aligned with the chosen headline, for once.

"Kids with cats have double the risk of developing schizophrenia" seems to line up with the study's conclusion that "Our findings support an association between cat exposure and an increased risk of broadly defined schizophrenia-related disorders". The odds ratio is greater than 2 which translates into a doubling of the risk (eg odds) and >25 years is an excursion criteria. The lower bound CI is > 1 so it's likely to be a real association. PLE is Psychotic Like Experiences that seems to be a broader definition, which does not have a significant association. This can be due to lack of studies with said definition or imply that the effect is specific to schizophrenia-related disorders. However, the causality part is not investigated.

I wonder how this may have impacted world history. Something along the lines of humans have grain storage >> rats are attracted to grain >> cats are attracted to rats >> humans are attracted to cats >> human populations with cats become slightly more schizoaffective (which in most premodern societies is not really pathological) >> these societies commune with the divine more/tell the future/develop more complex religious institutions >> these religious institutions help stabilize society

Kinda seems like a win-win to be honest.

Somebody read Snow Crash.... ?

This Snow Crash thing, is it a virus, a drug or a religion?

What’s the difference?

Yes

This:

https://wiki.c2.com/?NamShubOfEnki

The ideas in Snow Crash probably come in part from the bicameral mind theory: https://en.wikipedia.org/wiki/The_Origin_of_Consciousness_in...

From an evolutionary point of view I still think cats are the most successful animals. They have managed to get the ultimate apex predator (humans) to feed, care and provide shelter for them, in exchange for merely existing and looking cute.

How is this different from dogs?

Cats were useful, so were dogs.

Now they're both mostly just for being cute.

Dogs are generally better companions, but lots of people have dog-like cats that wanna be around them 24-7.

> Dogs are generally better companions, but lots of people have dog-like cats that wanna be around them 24-7.

I guess it depends on how you define "better". We have cats who snuggle with us in bed at night, but mostly do their own thing during the day, aside from little spurts here and there where they'd like (but don't demand) some attention.

Meanwhile, most of my friends' dogs annoy the hell out of me. No, I don't want you to jump on me and slobber all over my face every time I see you. And most of my dog-parent friends agree that their dog requires a lot more attention and work than our cats do.

To each their own, I suppose.

In reality cats are man's best friend. Dogs are a child surrogate, except they never reach an age where they're independent. Which is probably half the appeal: they never outgrow us, unlike our children (or our cats).

Any kind of companionship, even a mouse, can provide that kind of emotional support, but that says nothing of the animal's intent or ability to harm others. They are solitary creatures whereas dogs are social creatures. It's little wonder they would be carriers for parasites such as Toxoplasma gondii, whereas dogs aren't

If you ever watch the videos of the cats going outside with a camera, they almost always end up meeting up with other random neighborhood cats and interact and play. I don't think they're as solitary as people think.

We have a number in the house and they enjoy each other's company.

> They are solitary creatures

They're not. Feral cats form colonies with complex social structures: https://en.wikipedia.org/wiki/Feral_cat#Colonies

House cats are much more solitary creatures that are very jealous of their human slaves' relationships.

Just to expand upon what civilitty said: cats are solitary hunters, but live in social packs. They absolutely prefer to live socially if given the choice. Cats being solitary creatures is a myth.

Your rebuttal is also wrong, since cats do make decisions for the good of their colony.

Great point. I guess the 21st century will close out with at least an AI powered cat-dog, possibly a synthetic biological mutant cat-dog, possibly even a cyborg pet cat-dog with a brain internet interface for friend-foe identification, poisonous food identification, "I lost my pet", etc. Probably on a cloud license (you never really own your pet... all pets are the property of CloudCorp...)

Cats are not socially dependent animals. They are sole survivors. It makes perfect sense to me that cats would, like rodents, be common carriers of such diseases.

Feral house cats form colonies and are relatively social, although they typically hunt alone.

Rodents are extremely social, like people levels of social.

Not sure what point you're trying to make here.

I feel like we domesticated dogs and selectively bred them to follow commands and do what we want. For cats it's more like the other way around, they domesticated us and still have their complete independence.

I honestly feel that the majority of the 'cats are anti-social' is due to them being in chaotic households. we've rescued a number of cats over the decades and no matter how antisocial the family claims they were before they got rid of them, after a year or so they are just cuttle bugs in our house, which is quiet and very consistent schedule wise.

To me cats are a lot like introvert-leaning ambivert people. They enjoy being social, but context and consent are important, and energy for socialization is not boundless.

Plus cat pictures have evolved all over the internet and will affect vision systems in AI. Immortalizing the cat in the post - biological world

Cats also provide companionship and emotional support, and those are invaluable for humans.

Also, I wonder if it is really evolutionary if most of their current traits (physical and otherwise) were selected by humans.

Now excuse me, I must withdraw to tend to my feline masters.

Cats are very much social creatures. They can share activities (or, more often, lack thereof) with others. But they're not pack creatures like dogs.

>which in most premodern societies is not really pathological

Why? Crazy people have more often than not been severely repressed in former societies.

There's essentially no evidence for this.

Look up lead plumbing in the Roman Empire and the documented case of many emperors and council members being more "aggressive" than usual.

Lead plumbing pales in comparison to the lead they consumed via cooking pans (typically a lead / copper alloy) and a lot of Roman utensils used lead. Most tap water at room temperature won't absorb lead from pipes due to the mineral content and acidity. However, cooking in a pot made from lead will definitely poison you.

> these religious institutions help stabilize society

I'm not sure this is true, there are plenty of conflicts because of religion. I would argue the most stable would for nobody to be religious

How does the topic of toxoplasmosis gondii reappear every six months or so?

Reminds me of the Paul Graham article about submarine news placement.

http://paulgraham.com/submarine.html

I wish i knew how to compose one of those related article searches that dang does so well.

Imperfect search:

https://hn.algolia.com/?q=toxoplasmosis

But what firm could plausibly be behind a fusillade of articles relating cats to schizophrenia? Is this the work of Big Dog?

it is not a firm, it is the toxoplasmosis itself causing the posts.

It's actually called Puppy Co, you can learn more in the documentary "Boss Baby"

How can we be sure this comment isn't motivated skepticism in the service of Big Toxo?

It's news that touches a nerve. Many people have spent time around cats.

"touches a nerve"

I saw what you did there.

Because it’s a strange disease. Almost magical in some claims made of it.

There's so much BS around toxoplasmosis online. Here's corrections for two common misconceptions:

1) Almost everyone who has it got it from eating undercooked meat, not from cats. France has the highest rate of toxoplasmosis in the world because of their propensity for rare meats: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5312802/.

2) Unless your cat lived a long part of it's life as an outdoor cat, it is very unlikely to have the parasite (like any parasite).

> The researchers conducted an extensive study search across various databases and gray literature from January 1, 1980, to May 30, 2023, without geographical or language limitations. They included studies reporting original data on cat ownership and schizophrenia-related outcomes. Out of 1,915 identified studies, 17 were used from 11 different countries.

cherry picking studies to find some meaningful signal. Meta analysis is not a thing, it's just pseudo-science.

It'd be easy to rule this out. Cats who have been indoor-only without access to rodents are unlikely to have it. This would be a good distinction to collect/analyze if wanting to add credibility to the toxoplasmosis theory and rule out other cat related factors.

Any cat who lives in my house would have plenty access to rodents. Not sure if it would be as clean a line as you imagine.

I don't mean to judge, just an honest question: considering we're talking about indoor cats, how do you have plenty of rats inside your house? Is it something you can fix completely with professional services? It's what people usually do so I'm curious if it's a special case.

In my case, they lived in my neighbor’s unkempt yard and a few secluded spots from when the previous neighbor raised chickens. This summer, they moved out and the house was vacant for a month. First time in 20 years we found mice in our house. We did have them in our garage about 10 years ago until I changed some things.

Ah, that's bad. Perfect environment to reproduce and then of course they find their way in.

I'm thinking it wouldn't take much to spoil a study is all.

Even with some failures to keep rodents out of some homes, there's housld still be a pretty significant difference to be seen.

Why does indoor only preclude access to rodents?

Most people generally don’t have rodents in their house. Some pay especially good money to avoid such things

You’d be surprised. Maybe you just haven’t noticed them because you have a cat.

The cat would likely hunt them down and make sure the humans see that.

I'm from Eastern Europe and have never seen a mouse inside a house here. In Amsterdam they were everywhere.

That would still be hard to control for. I believe I recall reading that a T. gondii infection is something you get for life. Even if you adopt kittens from your local shelter at 8 weeks old, and then keep them indoors for the rest of their lives, they may have come in contact with rodents at some point before they made it to the shelter.

Hell, regardless of that, many homes in many places suffer rodent infestations at some point in time. Even if you get the exterminator in, it might be too late. This summer we bought a new house, and a few nights in, our (fully indoor) cat showed up to our bedroom, a (still breathing) mouse hanging from his mouth. So much for keeping him away from rodents.

The shedding of oocytes is how humans become infected. This is supposed to be stopped by the cats immune system a few weeks after initial infection. It is possible it could reoccur later if the cat's health changes as other life cycle stages exist in the cat.

Although I'm all for the study of T. gondii, they also state other factors that could affect schizophrenia outcome:

>> Environmental factors are also important. Epidemiologic studies, for example, have established that winter-spring birth, urban birth, and perinatal and postnatal infection are all risk factors for the disease developing in later life.

There's so much BS around toxoplasmosis online. And apparently in this article. Here's corrections for two common misconceptions:

2) Unless your cat lived a long part of it's life as an outdoor cat, it is very unlikely to have the parasite (like any parasite).

So I suspect toxoplasmosis is completely uninvolved in any correlation they may have found.

Hmm. My schizophrenic relative really likes cats. Could it just be a genetic predisposition to like cats is related to a genetic predisposition to the illness?

Alternatively, cats can smell schizophrenia.

"Genetic predisposition to liking cats" is a big stretch though.

This just seems like a review of previous studies, picking and choosing evidence/previous conclusions from tangentially related investigations. I can’t access the published paper but the article implies this area has been studied before, so I’m confused what this new paper is supposed to contribute. Is it just a literature overview?

I’m interested in getting a cat in the future so I’m interested in a proper study of this.

The article subtitle is a "A Systematic Review and Meta-Analysis".

Many good refs define both but [1] is free. As far as how you might think of them [2,3] give context. The exact extent of merit can be debated but these do have merit.

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5903119/ [2] https://ebm.bmj.com/content/21/4/125 [3] https://jamanetwork.com/journals/jama/fullarticle/1895230

"Meta-analysis"

https://en.wikipedia.org/wiki/Meta-analysis

Only somewhat related, but many of the comments highlight the importance of not using "rat" as shorthand for "rodent." Cats will happily sport-kill their way through mice, moles, and even rabbits, but they tend to leave rats alone because they are big and fight back.

https://sora.unm.edu/sites/default/files/journals/wilson/v08...

https://www.smithsonianmag.com/smart-news/cats-are-surprisin...

I was thinking about this the other day as well, I wonder how much pet ownership in general also has a direct impact on fertility. Not fertility rates (as in, couples choosing not to have kids get pets instead), but rather toxoplasmosis effects. One counterpoint is that in previous decades, many families in certain western countries had some sort of pet but also had many children, but I wonder if living spaces becoming smaller (esp in cities) has amplified a minor effect.

Anecdotally (tiny sample size of course), we know several couples trying without success, but those without pets seem to get pregnant moreso than those with.

Wow. Toxoplasmosis?

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3035534/

Sounds like we need to extinct toxo.

> This affinity may be related to the lack of a single enzyme in feline guts, delta-6-desaturase.

One route might be genetically engineering the introduction of the the gene(s) for this enzyme, if we can prove it reduces the infectiousness of the parasite.

Don't disturb the poop of wild animals without precautions. Don't let your cats outside.

There! Problem solved.

How do you stop toddlers from picking up pieces of cat poop from sandy areas in public playgrounds and sticking them in their mouths?

Mittens and muzzles.

(I'm joking, I'm joking!, look, we're 4 levels deep in HN's 50th joyous t.gondii thread here, allow me this innocent shitpost)

<looks at previous comment's dv's> Fair enough, it is indeed a cruel world where our children can't even eat animal faeces in safety, and any levity to the contrary should indeed be harshly punished - thank-you-sir-may-I-please-have-another? <bares back>

In this place up is down. You did good, kid.

Toxoplasmosis does not primarily infect humans from cats, and never indoor cats! Undercooked meat is the primary vector.

I find this funny since I have cats and also dissociative identity disorder, but I don't really think this article is correct.

This could easily be because dogs lower stress levels. That's assuming they had cats and no dogs at all.

Worth noting that the incidence of toxoplasmosis gondii in cats is heavily correlated with allowing them outside, which is where they usually contract it.

Surprise! If you let your animal outside and let it interact with, and even potentially consume, other wild animals, it may spread things!

This article draws conclusions only to support a clickbait title. There's no mention of the prevalence amongst cat cohorts. This is borderline fear mongering.

But don't simply listen to me, ask your vet.

Edit: would love to hear from down voters what about my comment they disagree with.

One of HN's special fixations is toxoplasmosis. Cats come up and there's a swarm of orange comments about how people like cats because they have a brain-control parasite.

Yep, so bizarre. I watched this climb to the top of the front page without any comments.

Maybe all the aspiring capitalists find this level of viral mind control... inspiring?

Cats come up and there's a swarm of orange comments

Just one. Unless the parasites tell me to post more.

My downvote comes from my reflexive downvoting of any comment that mentions downvotes.

Ho Ho Ho

Also most cases come from eating undercooked meat, not cats.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5312802/.

I've also heard that growing up with cats prevents allergies. Forget the source

All allergies?

Here a study that doesn't need "in mice". Maybe "not just in mice"?

Correlation/causation

2 words, cat poop.

Indoor cats don't have toxoplasmosis. That's a fact.

Is it common for cats to be exclusively indoor?

Yes? This is certainly common everywhere I’ve lived in the US, though it’s also common to have cats that go outdoors too.

I think a majority of the cat owners I know have indoor-only cats.

is it common for infected rats not to come indoors?

It depends where you live. Rats are less common outside the city. There are plenty of field mice and of course still some rats but they generally all stay outside as long as you've kept up with house maintenance.

We've had a few rats get into equipment outside our house over the years and probably a few (or squirrels) in the attic but to this date we've yet to see any evidence of one inside the house itself or anywhere the cats could get to them.

In the limited (but probably dominant, here at HN) context of middle-class-ish urban dwellers, I daresay there would be a sizeable proportion of clean, well-sealed modern homes in which rat ingress is at, or almost, zero.

Doubtless there is also a significant proportion of homes where rat ingress is more common.

But I couldn't begin to speculate about where those numbers might actually fall.

We usually have some appearance of a mouse once every couple of years. I suppose it’s possible others are getting in and being eaten by our cats or dog first, but that seems unlikely. Regardless, I believe cats which have eaten infected meat only shed oocytes for up to three weeks post-infection, and usually don’t shed again, so for most homeowners with indoor cats it’s probably a fairly low risk.

I believe gardening and playing around in dirt are both far more likely sources of toxoplasmosis infection anyway.

Even if these studies, barely making statistical relevance, were accurate, they still fail to highlight the fact that vitamin B3 cures schizophrenia

I am not aware of any testing that has approved vitamin B3 (niacin) as a treatment for schizophrenia. Perhaps you are thinking of vitamin B13.

At one time orotic acid was known as vitamin B13. It is no longer considered a vitamin. It is interesting that orotic acid can combine with lithium to form lithium orotate and some people believe it could be used as a treatment.

Lithium (carbonate) is sometimes used for the treatment of schizophrenia and although lithium orotate can also provide lithium, it has not passed testing for approval in any medical treatment that I have encountered.

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