photo: Center for Disease Control

Something bugging you? Better hope it's not Toxoplasma gondii, a parasite once thought to be harmless that Michigan State University researchers have recently linked to biochemical changes in the brain, some of which can lead to suicidal thoughts. The report, published in Biological Psychiatry, is based on a study that examined the blood work of more than 7,400 patients with mood disorders. The team found a higher concentration of the parasite in patients suffering from type 1 bipolar disorder. The MSU researchers discovered that people who test positive for the parasite are seven times more likely to commit suicide.

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"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," Lena Brundin, the lead researcher on the project, said in the report.

T. gondii is present in about a third of the world's population, but typically lies dormant. It can cause toxoplasmosis, which is particularly dangerous to people with weakened immune systems and women who are pregnant. T. gondii can cause inflammation in the brain, as well as other types of brain tissue damage.

Brudin, who has been studying brain chemistry and depression for more than a decade, believes that the low-seratonin levels in the brain commonly associated with depression are a symptom, and not a cause, of the disease. She admits that selective serotonin re-uptake inhibitors (SSRIs) are the most effective anti-depressant available today. Her research into how infections and parasites inflame parts of the brain, such as the T. gondii work, is directed at creating more effective treatments for people than SSRIs alone.

"I think it's very positive that we are finding biological changes in suicidal patients," Brundin told medicalnewstoday.com. "It means we can develop new treatments to prevent suicides, and patients can feel hope that maybe we can help them."