Because cats already have a reputation for acting aloof, sleeping all day and lashing out unprovoked, it only seems natural that kitty litter should be linked (however tenuously) to suicide, another of depression’s notorious side effects.

A parasite frequently found in kitty litter called Toxoplasma gondii infects a huge number of people—about one third of the world’s population. Though most will never know they have it as T. gondii lays dormant in the vast majority of people, Dr. Teodor Postolache of the University of Maryland’s School of Medicine discovered a link between T. gondii and certain psychiatric problems, including self-directed violence and suicide among mothers.

Looking at an ongoing allergy study in Denmark of 45,788 people between 1992 and 1995, Posolache and his researchers found that women infected with T. gondii had 2.05 percent higher risk of attempting suicide than women with no infection, and the “the risk seems to increase with increasing anti-body levels.”

2.05 percent doesn’t sound like a major “ah-ha” discovery, and the relationship may not be causal, but Dr. Charles Raison, associate professor of psychiatry at the University of Arizona in Tucson told CNN he believes that the research about T. gondii speaks to a connection between certain types of infection and psychiatric problems.

“We have these simple ideas about infection and illness like you get the influenza virus and then get the flu. One bug equals one illness. What we now know is it’s much more complicated than that. Infections can produce a lot of secondary effects,” he added.

In the context of the current study, that means T. gondii may not be causally linked to increased suicide risk, but a more global and complex process may begin with infection.

“It appears that toxoplasmosis does things that unbalance emotional mental functioning,” said Raison, CNNHealth.com’s mental health expert. “Depending on other risk factors, maybe it makes you depressed, maybe it makes you impulsive.”

So on the one hand, potential suicide by parasitic infection. On the other hand…

(via: The Chart)