Australian scientists are helping to develop a blood test that could determine if people are suicidal.
Scientists from the University of New South Wales (UNSW) hope their research will also help with the development of a new generation of anti-depressants.
Until now the focus for depression has been on the neurotransmitter serotonin. However, it has been discovered that severely depressed people have high levels of another neurotransmitter, a chemical called quinolinic acid.
The Australian team have been asked to help a Swedish team that, according to research published in the US, found the chemical "was significantly higher in suicide attempters than in healthy controls".
"We now know the mechanism and the molecule involved, so we have to find a simple way of testing it," said Associate Professor Gilles Guillemin from UNSW Medicine.
"We think it will take about 12 months to develop a test that could give doctors results in 24 to 48 hours," he told AAP on Wednesday.
The aim was for doctors to be able to use the blood results to complement other diagnostic work.
The NSW team, who are world leaders on the chemical, had previously demonstrated quinolinic acid is involved in several brain diseases, including Alzheimer's disease, autism and schizophrenia.
Ultimately, it's hoped that doctors in the future will be able to stop the production of quinolinic acid by using specific enzyme inhibitors to block its production.
Bob Goldney, Emeritus Professor of Psychiatry at the University of Adelaide, said the concept of a blood test was exciting.
However, "all too often over the past 30 years we have been disappointed".
"The prediction of suicide is difficult. A blood test would be interesting but probably not very useful in terms of it being a specific predictor because so many factors influence suicidal behaviour."
* Readers seeking support and information about suicide prevention can contact Lifeline on 13 11 14 or Suicide Call Back Service 1300 659 467.
© AAP 2019