Many people face major challenges or live with severe depression, but comparatively few commit suicide. So the question is: What is the trigger?

A series of studies has shown that the way in which a person makes decisions is among the main factors that determine whether that person is protected from or vulnerable to suicide. High-risk decision-making was prevalent among many parents of individuals who committed suicide, which may serve to explain its apparent "inheritability."

Dr. Fabrice Jollant, assistant professor of psychiatry at McGill University in Montreal, has researched the subject for many years. His latest study was published recently in the Journal of Psychiatric Research and helps to demonstrate how difficulty making effective decisions can predispose an individual to suicide and, by the same token, leads to potential solutions for prevention.

Suicidal thoughts must be studied indirectly. Previous studies have focused on individuals who have attempted suicide. To understand the vulnerability to suicide and study the family dimension, Jollant and his colleagues at the Douglas Mental Health University Institute in Montreal focused on close relatives of individuals who had committed suicide, including parents, brothers and sisters who were in good mental health. "We know that the close relatives of people who commit suicide carry certain traits linked to suicide vulnerability, even if they have never expressed them through a suicidal attempt," Jollant explained.

One of the neuropsychological tests used in the study was a betting game, in which players must win as much money as possible by choosing cards from among several piles. Some piles carry more risk: They sometimes pay off big, but they lose over the long term. Other piles are safer: The payoffs are small, but the losses also are small. While individuals from families without suicides learn to choose the piles that pay off over the long term, the relatives of suicide completers continue to make high-risk choices, even after numerous attempts, thereby demonstrating a higher degree of difficulty in learning from their experiences.

A functional MRI of the brain confirmed that certain areas of the prefrontal cortex that are used for decision-making function differently among these individuals and similarly to those who have attempted suicide.

"People who have a tendency to make risky decisions lean toward solutions that provide short-term benefits despite the high risk, instead of solutions that are safer over the long term," Jollant said. "They also have difficulty identifying alternative solutions when faced with a problem." This can explain the link between decision-making and suicide. "Within the context of a major depression, this difficulty making good decisions can translate into choosing death, which is a solution that ends the suffering immediately, despite its irreparable consequences, without seeing any alternative solutions."

In addition, making poor life choices creates a variety of stress factors. "We have specifically demonstrated that individuals who make risky decisions experience more problems in their personal relationships, which represent classic triggers for suicidal crises," Jollant said.

The study also points toward possible solutions for at-risk individuals, which must be confirmed by additional research.

"Beyond decision-making, we also found that the close relatives of suicide victims who were in good mental health performed very well in other tests, demonstrating the ability to control their thoughts," Jollant explained. "This may counterbalance their difficulty in making proper decisions and may have protected them from suicide. We can foresee developing psychotherapies that focus on decision-making and other cognitive functions in order to reduce the vulnerability to suicide."

Over the long term, the use of neurostimulation also may be included in the range of tools that are available to help individuals who exhibit suicidal tendencies.