Blood Test May Predict Risk of Suicide

A depressed-looking man sits with his hands on his head.
Predicting who is at risk of suicide is difficult, researchers say. (Image credit: Depressed man photo via Shutterstock)

It can be difficult to tell when a person is contemplating suicide -- people may be reluctant to speak about it. But now, researchers say they may have a new tool that reveals suicidal thoughts with a blood test.

The researchers found the levels of certain molecules in the blood differed when people with bipolar disorder were having suicidal thoughts, and they were able to confirm their findings in the bodies of men who had recently committed suicide.

"We found some blood biomarkers, some changes in molecules in the blood, that are associated with having a high suicidal risk, and then we validated those changes in blood from suicide completers," said Dr. Alexander Niculescu III, an associate professor of psychiatry and medical neuroscience at the Indiana University School of Medicine. 

Niculescu and his team spoke with 42 men with bipolar disorder who were being treated at various sites in Indiana. Nine of the men they spoke with, over the course of the study, fluctuated between having thoughts of suicide and not having those thoughts.

By examining the men's blood, the researchers found a number of molecules that appeared to correlate with those suicidal thoughts. The researchers compared their findings with the molecule levels in the blood from the bodies of nine men who had recently committed suicide, and had been matched for age, and they were able to narrow down the number of molecules. [5 Controversial Mental Health Treatments]

Finally, the researchers compared their blood sample findings to those from groups of the 42 men with bipolar disorder and 46 with schizophrenia, to see if the levels of these biomarkers corresponded with suicidal tendencies.

Ultimately, the researchers found six molecules that appeared to correlate with suicidal thoughts and actions. However, Niculescu noted the findings need to be confirmed in a wider cohort that includes women and non-Caucasian men.

It remains unclear why these particular molecules would have an impact on suicide, but, Niculescu said, some of them are involved in inflammation and cell death, so it may be that they affect people under extreme stress in a large way.

One of the reasons the research was conducted, said Niculescu, who also serves as a staff psychiatrist at the Indianapolis VA Medical Center, is that suicide has had a particular impact on members of the military, where it has claimed more active military members than the combat in Iraq and Afghanistan.

With the stigma attached to suicide, "We needed something else besides what people tell us to identify who's at high risk," Niculescu said.

The search for biomarkers that indicate suicide risk has long been a challenge for psychiatrists, said Dr. Andrew Leuchter, a professor of psychiatry and biobehavioral science at the University of California, Los Angeles, whose research group has looked at brain scans for a similar goal.

Because suicide is a rare but catastrophic event, it has presented a challenge to mental health professionals who want to help patients without simply characterizing large numbers of them as suicidal. Even with biomarkers, as important as they may be, doctors will still need strong interaction with their patients to intervene.

"It is very, very common for people who have…any of the most common serious mental illnesses to have thoughts of suicide, perhaps even to have planned to do it," Leuchter said. "There are a lot of people who do commit suicide, but if you're looking at any one group of individuals…the likelihood that any one person in that group is going to commit suicide is relatively low," making it hard for even professionals to tell who is at high risk.

The study is published online today (Aug. 20) in the journal Molecular Psychiatry.

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Joe Brownstein
Joe Brownstein is a contributing writer to Live Science, where he covers medicine, biology and technology topics. He has a Master of Science and Medical Journalism from Boston University and a Bachelor of Arts in creative writing and natural sciences from Johns Hopkins University.