Blood test may predict suicide risk some day: study

US researchers said Tuesday they have found a series of biomarkers in blood that may be used to identify who is at risk of suicide in the future.

Researchers from the Indiana University wrote in the journal Molecular Psychiatry that levels of the biomarkers may rise significantly in the blood of both bipolar disorder patients with thoughts of suicide and people who had committed suicide.

Principal investigator Alexander Niculescu said the results provided a first "proof of principle" for a test that could provide an early warning of somebody being at higher risk of an impulsive suicide act.

"Over a million people each year worldwide die from suicide and this is a preventable tragedy," said Niculescu, associate professor at the Indiana University School of Medicine.

"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," he said.

Over a three-year period, Niculescu and his colleagues followed a large group of patients diagnosed with bipolar disorder, completing interviews and taking blood samples every three to six months.

The researchers conducted a variety of analyses of the blood of a subset of participants who reported a dramatic shift from no suicidal thoughts to strong suicidal ideation.

They identified differences in gene expression between the "low " and "high" states of suicidal thoughts and found that the marker known as SAT1 and a series of other markers provided the strongest biological "signal" associated with suicidal thoughts.

Next, to validate their findings, they analyzed blood samples from suicide victims and found that some of same top markers were significantly elevated.

In the end, the researchers analyzed blood test results from two additional groups of patients and found that high blood levels of the biomarkers were correlated with future suicide-related hospitalizations, as well as hospitalizations that had occurred before the blood tests.

"This suggests that these markers reflect more than just a current state of high risk, but could be trait markers that correlate with long term risk," said Niculescu.

Although confident in the biomarkers validity, Niculescu said the limitation was that the research subjects were all male.

"There could be gender differences," he said. "We would also like to conduct more extensive, normative studies, in the population at large."

In addition to extending the research to females to see if the same or other markers come into play, Niculescu and colleagues plan to conduct research among other groups, such as persons who have less impulsive, more deliberate and planned subtypes of suicide.

"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," he said. "In the future we want to study and assemble clinical and socio-demographic risk factors, along with our blood tests, to increase our ability to predict risk."