Preventing suicide may be as simple as taking a blood sample, with recent research finding that a certain chemical in the brain is linked to suicidal behaviour.

A team of researchers at the University of New South Wales (UNSW) have discovered that the chemical in the brain, called quinolinic acid, is linked to suicidal behaviour. The acid is produced as a by-product of inflammation.

Suicide is the leading cause of death for people aged between 15 and 44, but hope may soon be at hand, with the team of researchers now working on a possible blood test to determine if a patient is at an elevated risk of suicide.

The research shows that people who have the strongest suicidal impulses have twice as much quinolinic acid in their bodies as healthy individuals.

The increased acid indicates greater signalling of the neurotransmitter glutamate between nerve cells. The acid acts like a chemical switch to make the glutamate send more signals to nearby cells. Until now the focus for depression has remained on another neurotransmitter, serotonin.

The researchers took the samples of the quinolinic acid from the spinal fluid of 100 patients in Sweden. Two-thirds of the participants had been admitted to hospital after a suicide attempt and the rest were healthy.

UNSW researchers, who are world-leaders in research on quinolinic acid, were brought in to analyse the samples.

“We have previously demonstrated that the neurotoxin quinolinic acid is involved in the neuroinflammatory response in several brain diseases including Alzheimer’s disease, autism and schizophrenia,” says Conjoint Associate Professor Gilles Guillemin from UNSW Medicine.

Ultimately, it is hoped that medical practitioners will be able to stop the production of quinolinic acid by using specific enzyme inhibitors blocking its production. Recently published clinical studies have shown the anaesthetic ketamine, which inhibits glutamate signalling, may be effective in combating depression, although its side effects currently limit its use.