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Amanda Mills Center for Disease Control and Prevention

A study on suicide links risk to levels of biomarkers that can be measured in blood tests. But experts say further research is needed to justify changes in suicide prevention and mental health treatment.

Blood test may identify risk of suicide

by Lauryn Schroeder
Aug 29, 2013

People contemplating suicide often keep their plans a secret from friends and family for fear of disgrace or hospitalization, but new research shows that the message may be in their blood. According to a new study, certain physical markers found in the blood stream may indicate whether someone is at a high, or low risk of suicide.

By comparing the blood of those who are suicidal, those who are not, and those who had previously committed suicide, researchers from the Indiana University School of Medicine and the VA Medical Center in Indianapolis identified levels of protein molecules that moved in tandem with suicidal thoughts. These protein molecules are also known as gene expression biomarkers that essentially show how active or inactive different genes are at a certain time.

“I think [the study] provides hope we can have some objective tests in the future, that are biologically based,” said Dr. Alexander Niculescu, an associate professor of psychiatry and medical neuroscience at the Indiana University School of Medicine in Indianapolis and one of the lead authors of the study, published online in Molecular Psychiatry. “Much more work needs to be done to integrate socio-demographic and psychological risk factors with blood biomarker data.”

Higher levels of the gene SAT1, and lower levels of CD24, have both been related to suicidal thinking, and while this research is in its formative stages, the biomarkers could be used to predict the mood state and psychosis symptoms in patients. But it’s still uncertain if the standard medical treatments for mental illness should based on this new imformation until more research is done, according to the study.

In 2010, which is the most recent data available, suicide was listed as the tenth leading cause of death for Americans, with 38,364 suicides that year. According to the National Institute of Mental Health, 10-  20 percent of people with bipolar disorder attempt suicide. Since the study required finding a test group who experienced dramatically different mental states over a shorter period of time, Niculescu said this research focused on a large cohort of psychiatry patients.

For the study, scientists sampled the blood of 75 male patients who had been diagnosed with bipolar disorder. Since those with bipolar disorder are more prone to suicide and often experience extreme mood changes, scientists were able to track any genetic changes in their blood stream. In addition to the blood sampling, the research team also conducted interviews every three-to-six months to determine the patients’ mental state at the time of testing.

Niculescu said out of the 75 men who were tested, a subset of nine men switched from no suicidal thought to high suicide ideation — or specific intents or plans to attempt suicide — from visit to visit. Blood samples were taken during both periods and were then analyzed to determine a change in gene expressions.

“We could then look within subjects at what molecular changes occurred in their blood in conjunction with this switch in suicidality,” he said. “[We then determined] which of those changes were common across the subjects studied.”

With the help of the Marion County Coroner’s Office in Indianapolis, scientists also examined additional blood samples taken from nine men who had committed suicide themselves by means other than a drug overdose. Those who had overdosed were excluded to eliminate the possibility of certain drugs influencing the blood tests. According to the study’s results, these nine men all showed elevated levels of SAT1. This level was also much higher than the already elevated levels seen in those who admitted having suicidal thoughts but had not attempted it.

“[There was] also a correlation with future hospitalizations for suicidalidty in two other independent cohorts of subjects, so we are reassured we are dealing with a real discovery,” he said.

Unlike similar studies in this field, where a large number of individuals are needed, Niculescu said they were able to use a smaller group, while also eliminating other factors that play into suicide.

“[Our approach] eliminates the usual genetic and environmental variability that you see in case-control type studies,” he said. “Which then require you to have thousands of research subjects to be able to detect some signal.”

David Litts, executive secretary for the National Action Alliance for Suicide prevention, said the research is a promising lead for further studies in this particular field, but more needs to be done for the public to see any change.

“This is just a gut feeling, but I think that there is great promise in this area of research,” said Litts. “The down side is that that this great promise is something that we won’t see for a while.”

Litts said for more progress to be made there needs to be more emphasis on the public health side, especially in injury prevention.

“Whether it’s how to restrict access to certain lethal means, including firearms, opiates, and other prescription and non-prescription drugs, or just the other aspects that go into someone taking their own life,” he said. “These are all bridges that can link to suicide and so we have to learn more about how they play into the grand scheme of things.”

Despite misconceptions surrounding suicide rates, Litts said they are actually decreasing among youths and elders. These two demographic groups where the rate has generally been high, have been declining over the past two decades. But the fight is far from over.

“It’s the middle age adults, ages 35 to 64, which have had significantly rising rates, or attention getting rates that we’re quite concerned with,” he said.

As for the reason behind this jump, there are a number of factors including an unstable economy, growing disparity between the upper and middle classes, and what Litts calls a cohort effect.

“It may be a generational thing, where a group has had high suicide rates for decades, and they’re now in this generation where they’re more susceptible,” he said. “Those are a couple leading theories but again there’s no proof.”

Proof is challenging to pin down in this field, where the research straddles biology, psychiatry and behavioral studies. According to clinical psychologist Kalman J. Kaplan, focusing on the biology of suicide alone might be the wrong route to take.

As a professor with the Departments of Psychiatry and Medical Education at the University of Illinois at Chicago, Kaplan has helped research several psychiatric studies involving suicidal activity. His most recent 2012 study looked into gender-specific risk factors for suicidal activity among schizophrenic and depressed patients. He has also written about improving the meaning of life on a spiritual level as a suicide prevention tool.

“Suicide is an act and therefore it’s a behavioral issue, not a biological one,” he said. “It’s seen as way out for some people. That to end their own life is their only option and that’s the behavior we need to change.”

Regardless of what type of research is done, Niculescu said preventing the tragedy of suicide should be the motive behind any current or future studies involving mental health.