TUESDAY, Aug. 20 (HealthDay News) -- Levels of certain blood
proteins may rise before a person commits suicide, a small study
suggests, and researchers hope the findings will lead to an
objective way to measure suicide risk.
Any such test is a long way off, experts say. But the new
research, published online Aug. 20 in the journal
Molecular Psychiatry, is a step in that direction.
Using blood samples from nine men with bipolar disorder,
researchers were able to isolate a group of proteins that rose or
fell when the men worsened from having no suicidal thoughts to
What's more, a few of those proteins were particularly high in
blood samples from another group of men who had committed
It all raises the possibility of developing a blood test that
could help psychiatrists gauge suicide risk in patients with
bipolar disorder or other mental illnesses, such as major
But nothing like that is "ready for prime time," said Dr.
Charles Luther, director of inpatient and emergency psychiatry at
Lenox Hill Hospital in New York City.
"We're not yet ready for a blood test to predict suicide risk,"
said Luther, who was not involved in the study. But, he added, the
results are "interesting," and an objective test for gauging
suicide risk is needed.
"It's very difficult to pin down risk," Luther noted.
Psychiatrists can look at a patient's history and what's happening
in his or her life at that moment. Beyond that, Luther said, "all
we can do is ask them what's going on in their mind."
The problem is, they may not admit the truth, said study author
Dr. Alexander Niculescu, an associate professor of psychiatry at
Indiana University School of Medicine in Indianapolis.
"They don't want to be stigmatized, or hospitalized. Or they may
not want to be stopped," Niculescu said.
Suicide is, fortunately, relatively rare. Still, "over 1 million
people worldwide commit suicide each year, and those deaths are
preventable," Niculescu said.
For the new study, the researchers first focused on nine men
with bipolar disorder who were part of a larger, long-term research
project. During the course of that study, all nine men had gone
from having no suicidal tendencies to contemplating or attempting
Looking back at the men's blood samples, Niculescu's team found
41 proteins whose levels changed when the men became potentially
Next, the researchers turned to the coroner's office to get
blood samples from nine men the same age who had committed suicide.
In the end, six proteins stood out as being strongly linked to
suicide risk: They had risen in the nine bipolar patients, and were
even higher in the men who'd actually gone through with
The protein with the greatest change was one called SAT1, which
is involved in "programmed cell death" -- where damaged body cells
essentially commit suicide. Some of the other proteins are involved
in inflammation and the body's stress response, Niculescu said.
It's not clear why the proteins were related to suicide risk.
And Luther said the findings do not mean that spikes in the
proteins "cause" people to commit suicide. "It's just a
correlation," he said, and not a cause-and-effect relationship.
But he and Niculescu said the findings could eventually give
some insight into the biology of suicide.
First, however, Niculescu said additional studies need to look
at women and people of other ethnicities since the men in this
study were all white. (One postmortem blood sample was from a black
man.) They also need to focus on patients with other mental
illnesses, such as major depression, he added.
Dr. Morton Silverman, senior science advisor to the Suicide
Prevention Resource Center in Washington, D.C., agreed that the
findings are preliminary and limited to this particular group of
Another issue, Silverman said, is the way the study defined
"suicidality" in the men with bipolar disorder. They were
considered to be "high" in suicidal ideation if they had attempted
suicide, or if they'd had "any thoughts" about their own death, or
wished they were dead. But those are very different states,
Silverman noted; someone with a past suicide attempt is clearly at
increased risk, while someone who has thought about death may not
be suicidal at all.
Still, he praised the "sophistication and creativity" of the
work, in finding blood markers that might be associated with "a
range of suicidal thoughts, intent or attempts," at least in this
group of men.
Even if a blood test for suicide risk becomes reality, it would
only be one part of assessing patients, Niculescu said. "You're not
just going to rely on a blood test to recommend that someone be
hospitalized," he noted.
Instead, he said, a psychiatrist might use the test along with
other information on a patient's risk factors, and questions about
his current depression and anxiety symptoms.
No single test will ever determine a treatment plan, Luther
agreed. "We're dealing with human beings, with complex emotions and
experiences," he said. "We need to know more about them than just
blood test results."
The National Suicide Prevention Lifeline offers
help to people at risk.