"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," said Dr. Alexander Niculescu, director of the Laboratory of Neurophenomics at the Institute of Psychiatric Research at the IU School of Medicine.
"We need better ways to identify, intervene and prevent these tragic cases," Niculescu said.
For the study, published in the journal Molecular Psychiatry, Niculescu and his colleagues followed a group of bipolar patients over three years, conducting interviews and collecting blood samples every three to six months.
Researchers then analyzed the blood of a subgroup who reported a dramatic shift from no suicidal thoughts to strong suicidal thinking. They identified differences in gene expression between "low" and "high" suicidal thinking, and conducted genetic and genomic analyses.
Researchers identified the marker SAT1 as the strongest biological marker for suicidal thoughts, followed by a series of other markers.
To validate their findings, researchers analyzed blood samples of suicide victims and found those top markers to be significantly elevated.
Blood tests from two additional groups of patients revealed elevated blood levels of the biomarkers correlated with future suicide-related hospitalizations, as well as prior hospitalizations.
"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.
Niculescu is confident in the validity of the proof of principle, but notes his study is limited in that only men were analyzed.
"There could be gender differences," Niculescu said. "We would also like to conduct more extensive, normative studies, in the population at large."
"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, but there are other types of more deliberate, planned suicide.
"Suicide is complex: in addition to psychiatric and addiction issues that make people more vulnerable, there are existential issues related to lack of satisfaction with one's life, lack of hope for the future, not feeling needed, and cultural factors that make suicide seem like an option."
But with further study researchers hope to find out early who could be at risk for all types of suicide. "Over a million people each year world-wide die from suicide and this is a preventable tragedy," Niculescu said.