Scientists have identified unusual patterns of brain activity that appear to be associated with an increased risk of suicidal thoughts and behaviors.
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The study suggests that changes in two key brain networks involved in decision-making and emotion can increase the likelihood that a person will think about or try to commit suicide.
The changes are not significant enough to enable at-risk individuals to be identified, but “we hope it will provide us with more information about what may be happening in terms of brain mechanisms,” says co-first author Anne-Laura van Harmelen from the University of Cambridge.
Suicide is one of the world’s leading causes of death
The researchers say their review shows how little research has been conducted into one of the world’s leading causes of death, especially amongst the most susceptible groups.
Suicide accounts for around 1 million deaths every year globally and is the second leading cause of death among people aged 15 to 29 years.
“Imagine having a disease that we knew killed almost a million people a year, a quarter of them before the age of thirty, and yet we knew nothing about why some individuals are more vulnerable to this disease,” says van Harmelen. “This is where we are with suicide. We know very little about what’s happening in the brain, why there are sex differences, and what makes young people especially vulnerable to suicide.”
The team reviewed 131 brain imaging studies
For the study, the team reviewed 131 brain imaging studies looking at patterns of brain activity among more than 12,000 individuals.
Generally, the studies compared people with a mental health condition who had previously become suicidal to people with a similar condition who had not become suicidal or to people who did not have a mental health condition.
Combining the results of all of the studies, Van Harmelen and colleagues looked for any structural, functional, and molecular alterations that seemed to be associated with an increased risk for suicide.
Two brain networks appeared to play an important role
As reported in the journal Molecular Psychiatry, they found two brain networks that appeared to play an important role.
One of the networks involves regions at the front of the brain called the medial and lateral ventral prefrontal cortex and their connections to other parts of the brain that are involved in emotion.
“The reviewed literature suggests that impairments in medial and lateral VPFC regions and their connections may be important in the excessive negative and blunted positive internal states that can stimulate suicidal ideation,” writes the team.
The second network involves regions called the dorsal prefrontal cortex and inferior frontal gyrus system.
Changes in this network, which is involved in decision making, regulating behavior, and generating solutions to problems, may influence whether a person goes on to attempt suicide.
The researchers suggest that if changes arise in the structure, function, or biochemistry of both networks, this may trigger negative, uncontrolled thoughts that may increase a person’s risk of suicide.
There has been too little research, says the team
The team says their review highlights how little research has focused on suicide, particularly research looking at sex differences and vulnerable groups.
For example, although transgender individuals are known to be at an increased risk for suicide, only one individual among the 12,000 people studied was identified as transgender.
“There are very vulnerable groups who are clearly not being served by research for a number of reasons, including the need to prioritize treatment, and reduce stigma,” says van Harmelen. “We urgently need to study these groups and find ways to help and support them.”
Co-author Hilary Blumberg (Yale School of Medicine) says the team’s review provides evidence to support a very hopeful future in which new and improved ways to reduce the risk of suicide will be found.
“The brain circuitry differences found to converge across the many studies provide important targets for the generation of more effective suicide prevention strategies. It is especially hopeful that scientists, such as my co-authors on this paper, are coming together in larger collaborative efforts that hold terrific promise,” says Blumberg.
The team says future research should consider whether their proposed model relates to future suicide attempts and whether there are any therapies that can alter the structure or function of the brain networks identified and thereby reduce suicide risk.
The HOPES study
In 2018, the researchers launched the HOPES (Help Overcome and Prevent the Emergence of Suicide) study, which brings together data available for around 4,000 young people across 15 countries. The aim is to develop a model that can predict who is at risk of suicide.
The team will study people’s brain scans and information on their environment and psychological traits in relation to suicide in order to identify specific, universal risk factors.
For many individuals, this will be during adolescence. If we can work out a way to identify those young people at greatest risk, then we will have a chance to step in and help them at this important stage in their lives.”
Co-first author Lianne Schmaal, University of Melbourne
Schmaal, L. et al. (2019). Imaging suicidal thoughts and behaviors: a comprehensive review of 2 decades of neuroimaging studies. Mol Psychiatry doi:10.1038/s41380-019-0587-x