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2nd February 2015

Could a blood test predict suicide risk?

A simple blood test may be a reliable way to screen people for suicide risk. The test looks for changes in a gene that helps the brain manage stress and control impulsive behavior.

“Suicide is a major preventable public health problem, but we have been stymied in our prevention efforts because we have no consistent way to predict those who are at increased risk of killing themselves,” says Zachary Kaminsky, assistant professor of psychiatry and behavioral sciences at Johns Hopkins University School of Medicine.

“With a test like ours, we may be able to stem suicide rates by identifying those people and intervening early enough to head off a catastrophe.”

Mutated Gene

In a series of experiments described online in the American Journal of Psychiatry, researchers focused on a mutation in a gene known as SKA2. Looking at brain samples from mentally ill and healthy people, they found that SKA2′s production of proteins was significantly reduced in people who had died by suicide.

Within this common mutation, they then found in some subjects an epigenetic modification that altered the way the SKA2 gene functioned without changing the gene’s underlying DNA sequence.

The modification added chemicals called methyl groups to the gene. Higher levels of methylation were then found in the study subjects who had killed themselves and in suicide victims in two other collections of brain tissue.

The researchers also tested three different sets of blood samples, the largest one involving 325 participants in the Johns Hopkins Center for Prevention Research Study. They found similar SKA2 methylation increases in individuals with suicidal thoughts or attempts. They then designed a model analysis of blood samples that predicted with 80 to 96 percent accuracy which participants were experiencing suicidal thoughts or had attempted suicide.

Cortisol-Suicide Link

The SKA2 gene makes proteins in the prefrontal cortex of the brain, which is involved in inhibiting negative thoughts and controlling impulsive behavior. SKA2 is specifically responsible for chaperoning stress hormone receptors into cells’ nuclei so they can do their job.

If there isn’t enough SKA2 protein, or it is altered in some way, the stress hormone receptor is unable to suppress the release of cortisol throughout the brain. Previous research has shown that cortisol release is abnormally high in people who attempt or die by suicide.

A test based on these findings might be used to predict future suicide attempts in those who are ill, to restrict lethal means or methods among those at risk, or to make decisions regarding the intensity of intervention approaches, Kaminsky says.

“We have found a gene that we think could be really important for consistently identifying a range of behaviors from suicidal thoughts to attempts to completions. We need to study this in a larger sample but we believe that we might be able to monitor the blood to identify those at risk of suicide.”

Soldiers At Risk

It might make sense for the military to test whether soldiers have the gene mutation that makes them more vulnerable, Kaminsky says. Those at risk could be more closely monitored when they returned home after deployment. A test could also be useful in a psychiatric emergency room, he says, as part of a suicide risk assessment when doctors try to assess level of suicide risk.

The test could be used in all sorts of safety assessment decisions like the need for hospitalization and closeness of monitoring. Another possible use that needs more study could be to inform treatment decisions, such as whether or not to give certain medications that have been linked with suicidal thoughts.

The National Institute of Mental Health, the Center for Mental Health Initiatives, the James Wah Award for Mood Disorders, and the Solomon R. and Rebecca D. Baker Foundation supported the study.

Source: Johns Hopkins University

This article originally appeared on Futurity on 31 July 2014.

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