London - Scientists have identified two brain "circuits" activated in people with suicidal thoughts – raising hopes of spotting those at a heightened risk of killing themselves.
Suicide is one of the world’s major killers. Overall, three times as many men as women took their own lives, although rates among women are rising.
Worldwide, 800 000 die by suicide every year and it is the second leading cause of death among 15 to 29 year olds.
Now scientists say, based on two decades of research, that two key brain networks have been identified which increase the risk a person will think about and attempt suicide.
Study co-first author Dr Anne-Laura van Harmelen, of Cambridge University, said: "Imagine having a disease that killed almost a million people a year, a quarter of them before the age of 30, and yet we knew nothing about why some individuals are more vulnerable to this disease.
"This is where we are with suicide. We know very little about what’s happening in the brain." They examined 131 studies, involving more than 12 000 participants, looking at alterations in brain structure and function.
Researchers identified two brain networks that appear important. The first involves frontal brain areas, known as the medial and lateral ventral prefrontal cortex, which helps regulate emotion. Alterations in that network may lead to excessive negative thoughts.
The second network – the dorsal prefrontal cortex and inferior frontal gyrus system – is active in decision making and controlling behaviour.Alterations may influence the chances of a suicide attempt.
Changes in both networks can lead people to think negatively, ‘blunt’ positive thoughts, and become more prone to suicide. Professor Hilary Blumberg, of Yale School of Medicine in the US, said: "The review provides evidence to support a very hopeful future in which we will find new and improved ways to reduce risk of suicide."
Study co-first author Dr Lianne Schmaal, from the University of Melbourne in Australia, said: "If we can work out a way to identify those young people at greatest risk, we will have a chance to step in and help them."
The findings were published in the journal Molecular Psychiatry.