Parasite tied to self-harm, suicide attempts

Women who are infected with a common parasite may be more likely to hurt themselves or attempt suicide, a new study of over 45,000 new moms in Denmark suggests

The infection, known as toxoplasmosis, is caused by the parasite Toxoplasma gondii. Humans can become chronically infected by eating undercooked meat or unwashed vegetables or by handling cat litter, as the parasite is known to multiply in the gut of infected cats.
Toxoplasmosis is often symptom-free, but can be dangerous in people with weak immune systems or during pregnancy, since the parasite may be passed to babies.
Some studies have linked the parasite to a higher chance of developing schizophrenia, and researchers believe because the T. gondii parasite lives in the brain, it could have an effect on emotions and behavior.
For the new report, Dr. Teodor Postolache from the University of Maryland School of Medicine in Baltimore and his colleagues used Danish medical registries to track 45,788 women who were originally included in a study that screened newborn babies for toxoplasmosis.
All of the infants were tested for antibodies against the parasite through a blood sample drawn five to 10 days after birth. Because the babies were still too young to make their own antibodies, any that showed up in their blood would have been passed from moms.
Just over one-quarter of the babies were positive for T. gondii antibodies, meaning their mothers likely had a chronic, underlying toxoplasmosis infection.
And over the next 11 to 14 years, infected women were about 50 percent more likely to cut, burn or otherwise hurt themselves, according to their medical records, and 80 percent more likely to attempt suicide.
In total, 488 women hurt themselves for the first time during the study - or eight out of every 10,000 annually - and 78 tried to kill themselves.
Eighteen women in the study committed suicide, which was too small a number for the researchers to determine whether T. gondii put some women at higher risk, according to their findings published this week in the Archives of General Psychiatry.
Postolache and his colleagues note that some instances of self-harm might not have shown up in their records if women weren't seen at a mental health clinic after the incident.
Based on the study, they also can't say for sure whether toxoplasmosis infection caused women to hurt themselves or attempt suicide. It could be, for example, that women with underlying mental problems were more likely to pick up the parasite because they cooked their meat or washed their vegetables improperly.
But it's reasonable, Postolache added, that the parasite could directly affect the brain, such as by making cells produce more or less of certain neurotransmitters that control mood and behavior.