A COMMON parasite found in cats may have a fearful and uncommon effect: Spurring its human hosts towards suicide.

A study published in the August issue of the Journal of Clinical Psychiatry has found people infected with the Toxoplasma gondii parasite are more than seven times more likely to attempt suicide.

The T.gondii is parasite generally found in cats, but can be transferred to a human host through ingesting its eggs.

Lena Brundin, associate professor of experimental psychiatry at Michigan State University, says her research has shown the parasite can cause inflammation which, in turn, produces metabolites that damage the brain.

"Research has found signs of inflammation in the brains of suicide victims and people battling depression," she said.

"In our study we found that if you are positive for the parasite, you are seven times more likely to attempt suicide."

The study reports between 10 to 20 per cent of people in the United States carry the parasite, which mostly lays dormant within their bodies.

Professor Brundin stressed that the majority of people infected with the parasite will not attempt suicide.

"Some individuals may for some reason be more susceptible to develop symptoms," she says.

"It is estimated 90 percent of people who attempt suicide have a diagnosed psychiatric disorder. If we could identify those people infected with this parasite, it could help us predict who is at a higher risk."