For the first time, researchers have found that a chemical in the brain called glutamate is linked to suicidal behavior. While previous research and drugs have targeted serotonin to fight severe depression, this study shows that more attention should be paid to this chemical.

Glutamate is an amino acid that fires signals between nerve cells. It has long been suspected to be a culprit for depression, and this study seems to confirm that.

The study examined 100 people who checked into a hospital in Sweden. Two-thirds had been hospitalized after suicide attempts; the other third was hospitalized due to unrelated issues.

Researchers measured the participants' glutamate activity by assessing the level of quinolinic acid in the people's spinal fluid. High amounts of quinolinic acid indicate high amounts of glutamate activity.

Indeed, researchers' findings confirmed their hypotheses. The research indicated that the patients who had attempted suicide had quinolinic levels that were twice as high as the controls had. That indicated that their glutamate levels were far higher than that of healthy people. The patients who had reported having the strongest desire to kill themselves also had the highest levels of quinolinic acid.

Six months later, some of the patients were tracked so that researchers could test their quinolinic fluid once more. The patients who had attempted suicide all had much lower quinolinic fluid levels months after their suicidal behavior.

The research also indicates why brain inflammation has been linked to suicidal behavior. Quinolinic fluid is produced as part of an immune system response that creates the same brain inflammation.

Though there are no anti-glutamate drugs currently on the market for depression, there are some in development. Ketamine has also been shown to be successful in battling glutamine, though its side effects have prevented it from being used widely. Ketamine is also known by its street drug name Special K.

The study was published in the journal Neuropsychopharmacology.