Inflammation in the Brain

Lena Brundin, of Michigan State University, co-led the new study. She told the press that between one in ten and one in five people in the US carry the parasite, and while it was thought to lie dormant, it in fact appears to cause inflammation that produces metabolites that accumulate over time and can harm the brain.

“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,” said Brundin, an associate professor of experimental psychiatry in the College of Human Medicine at MSU.

For example, last month saw the publication of a study that linked higher suicide risk in new mothers to T. gondii.

What the New Study Found

The study is the first to use a suicide assessment scale to assess risk in people infected with the parasite, including 54 who had attempted suicide and 30 controls. All patients were adults and were recruited between 2006 and 2010, and were tested for signs of the parasite. The 54 who had attempted suicide were inpatients at Lund University Hospital in Sweden, and the controls were randomly selected from the municipal population register in Lund.

The results showed testing positive for the parasite was significantly tied to higher scores on the scale, which would indicate a higher risk of a future suicide attempt.

“… we found that if you are positive for the parasite, you are seven times more likely to attempt suicide,” said Brundin.

However, Brundin emphasized that most people infected with the parasite are unlikely to attempt suicide:

“Some individuals may for some reason be more susceptible to develop symptoms,” she explained.