That might be a little misleading. What we do know is that being around cats increases exposure to the Toxoplasma gondii parasite — and that, in turn, can cause mental illness, possibly leading to suicide.
But T. gondii is actually very common: about a third of the world's population is infected. Cat owners are more likely to have it because it can be transmitted through cat poop, and thus is often found in litter boxes.
Researchers studied 45,000 women in Denmark to look for a connection between T. gondii infection and suicide. This was the largest ever study on the subject, and the first to document suicide attempts after infection had been discovered. Apparently, women infected with T. gondii are one-and-a-half times more likely to attempt suicide, and the more widespread the infection, the greater the risk.
Senior author Teodor Postolache of the University of Maryland School of Medicine explained that the connection is still tenuous.
We can't say with certainty that T. gondii caused the women to try to kill themselves, but we did find a predictive association between the infection and suicide attempts later in life that warrants additional studies. We plan to continue our research into this possible connection.
Rest assured, you don't need to be a cat owner to contract the parasite. While it's often found in cat intestines, you can also get it from undercooked meat and unwashed vegetables.