I do psychosis research. I was taught at one point that the proposed mechanism to explain the “tentative and small” link between cat ownership and schizophrenia is that toxoplasmosis is common in cat feces and that infection thereby may raise risk of chronic psychosis. I never followed any of the literature—it was more of a factoid and a “hey this is a cool but niche thing people are studying,” but I will say that this paper doesn’t come totally out of left field. That said, I think this supposed link is probably not very robust. A similar factoid in our subarea is that people born blind cannot develop schizophrenia, but I always point out to people that schizophrenia is already rare (0.5% or so) and being born blind *even more rare than that,* so the combinatorics work out to a very small percentage of folks who likely just haven’t been observed and written about.