Researchers from the Michigan State University found that a common parasite Toxoplasma gondii can cause inflammation over time, which produces harmful metabolites that can damage brain cells.
"Previous research has found signs of inflammation in the brains of suicide victims and people battling depression, and there also are previous reports linking Toxoplasma gondii to suicide attempts," Lena Brundin, an associate professor at MSU said.
"In our study we found that if you are positive for the parasite, you are seven times more likely to attempt suicide," she said in a statement.
The study measured scores on a suicide assessment scale from people infected with the parasite, some of whom had attempted suicide.
The results found those infected with T gondii scored significantly higher on the scale, indicative of a more severe disease and greater risk for future suicide attempts.
T gondii is a parasite found in cells that reproduces in its primary host, any member of the cat family. It is transmitted to humans primarily through ingesting water and food contaminated with the eggs of the parasite, or, since the parasite can be present in other mammals as well, through consuming undercooked raw meat or food.
The study was published in The Journal of Clinical Psychiatry.