Are cat owners depressed? That’s a questions researchers at the University of Michigan have been asking themselves.

After analyzing the medical records of 1.3 million patients seen by the university’s health system over the span of 10 years, researchers found that a startling number of people who were bitten by cats were also diagnosed with depression.

According to the study published in the science journal PLOS ONE earlier this week, depression was found in 41 per cent of patients who had been bitten by cats. On the other hand, only 29 per cent of people who were bitten by dogs had been diagnosed with depression.

Furthermore, researchers found a 47-per-cent chance that women bitten by cats will also be diagnosed with depression, compared to 24 per cent of bitten men.

“It may seem counterintuitive to consider screening for depression in someone who presents to a clinician with an acute injury from a household pet, but our findings suggest that it could be beneficial,” researchers say.

So what do the results mean? Do cat bites lead to depression?

Well, probably not. 

Michigan researchers say it’s possible that depressed people are more likely to own pets, which, according to studies, have been shown to reduce blood pressure and provide social support.

“As such, it may be that depressed individuals, especially women, are more likely to own cats for companionship,” the researchers write.

Another possible explanation is that cats may bite their owners if they see a change in their mental state. The study says that “depressed individuals often make less eye contact compared to those without depression,” which may make them more susceptible to cat bites.

And possibly most worrying is the parasite Toxoplasma gondii, commonly found in cats. The parasitecan be transferred from cat to owner, causing long-term brain effects, and may contribute to schizophrenia and obsessive compulsive disorder, the study says.

The parasite, however, is not thought to be transmitted via cat bite, but rather “shed in the feces of cats.”

While researchers haven’t found a causative link between cat bites and depression, they say there is “growing evidence to suggest that the relationship between cats and human mental illness, such as depression, warrants further investigation.”