Or maybe that's just the T. Gondii talking.

And they're fluffy and cute and a nice friend :-)

For real! Isn't that terrifying?

Also, as many can-openers will know, some others will watch you doing your thing, without you being able to stop them, and learn from that to use the loo in comical but clean ways.

Comical as in how they crouch on the lid, hind legs spread wide, butt hanging low over the middle, forelegs on the front. Clean as in not hitting the lid. They basically want their shit "gone" without having to mess with it. If they see/watch/understand/learn a possibility to do that, they'll use it. (In my personal experience with the small sample size I have. Though there are many writings from others, describing the same)

That would be a dog.

She ended up moving in with my aunt when she couldn't look after herself any more. My aunt had a small black cat. At first my grandma hated it. She was terrified of it, would shoo it away, kick him outside and stuff. But after a few months of living there, out of nowhere like a switch had been flipped, she suddenly loved that cat. She'd spend hours watching TV with him on her lap, would go looking for him to give him treats, would get concerned if he was outside too long, that cat became one of her favourite things.

I mean maybe she just had a change of heart after a lifetime of ingrained hatred and fear, but her attitude towards pretty much everything else never really changed.

Also the conclusion of the study you linked is that toxoplasmosis isn't linked to depression but scratching is. I found this unexpected given the wording of your post.

Edit: also when you clip a cat's claws it can't really scratch you. I'd also assume someone who can be described as depressed is less likely to clip or get their cats claws clipped often enough to prevent scratches.

I’d also suggest that the toxo-inflicted depression will be offset by the many added joys of being personally owned by a furry, purry, and only occasionally—ow, sharp!—bundle of utterly adorable fluff. Which is to say, humans are a bit more complex than ants, thus effects will be a lot less clear-cut.

the number of cats at home had a negative effect on depression (p = 0.021).

Suggesting that getting a cat is a good idea for someone concerned about depression. Of course, it may be that depressed people are less willing to take on the responsibility of pet ownership.

(just to make myself clear...)