Could a blood test predict suicide risk?
People at risk for suicide don't always show signs of their vulnerability. But a test that can scan biomarkers to predict actual suicidal impulses? While promising, it may go only so far.
Those pondering suicide may not tell anyone for reasons including isolation, shame, or fear of stigma or hospitalization. But researchers from the University of Indiana say a blood test could one day reveal such thoughts.
In a study published Tuesday in the journal Molecular Psychiatry, scientists from the university's School of Medicine cite a series of RNA molecules, or biomarkers, that they observed at higher levels in a group of bipolar disorder patients with suicidal thoughts, as well as in people of the same age who had actually committed suicide and whose blood was tested shortly after they died.
"Suicide is a big problem in psychiatry. It's a big problem in the civilian realm, it's a big problem in the military realm, and there are no objective markers," Dr. Alexander B. Niculescu III, an associate professor of psychiatry and medical neuroscience at IU School of Medicine and an attending psychiatrist at the Veterans Affairs Medical Center in Indianapolis, said in a statement. "There are people who will not reveal they are having suicidal thoughts when you ask them, who then commit it and there's nothing you can do about it. We need better ways to identify, intervene, and prevent these tragic cases."
Over the course of three years, a team led by Niculescu followed a large group of patients diagnosed with bipolar disorder, a demographic that studies show (PDF) has an annual suicide rate at least 10 times that of the general population. The scientists regularly interviewed the subjects and collected blood samples, closely analyzing the blood of a subset of nine men who reported a strong shift from no suicidal thoughts to frequent such thoughts.
That's a small, gender-specific sample, and the scientists acknowledge that predicting suicidal thoughts and feelings may be different than prognosticating suicidal behaviors. Such caveats led Dr. Amit Etkin, an assistant professor of psychiatry and behavioral sciences at Stanford University School of Medicine, to approach the study results cautiously. Still, "this is an intriguing initial study with some promising results," he told CNET.
The data comes from the same group that has previously studied the use of blood biomarkers to predict mood state and psychosis symptoms.
Building on methods used in that earlier work, the team looked at how genetic data differed between subjects with high and low degrees of suicidal thoughts. Of the biomarkers studied, they found that one enzyme, SAT1, served as a particularly strong biological "signal" for suicidal thoughts.
Working with the local coroner's office to analyze blood samples of suicide victims, they found elevated levels of some of the same markers.
"These seem to be good markers for suicidal behavior in males who have bipolar mood disorders or males in the general population who commit impulsive violent suicide," Niculescu said. In the future, his group plans to study women and other groups and assemble tools, including neuropsychological tests and socio-demographic checklists, that could work alongside blood tests for better suicide prediction.
But what, exactly, could cause the shifts in blood chemistry? Etkin, who runs Stanford's Etkin Lab, which studies the neural basis of emotional disorders and their treatment and works closely with the Palo Alto VA, says the changes likely reflect alterations in stress responses, anxiety levels, and the like.
Can a blood test read minds?
"It would be a far cry for a blood test to 'read your mind,'" he said. "If anything, the blood test should be a measure of general biological processes which are relevant to both suicide and a number of other factors common in individuals who have an increase in suicidality, along with other symptom changes."
And there are, of course, considerations beyond biology, as a complex maze of existential and cultural factors can also play a role in suicides.
"Over a million people each year worldwide die from suicide," Niculescu said, "and this is a preventable tragedy."