A simple blood test to reliably predict a person's risk of attempting suicide may soon be possible, scientists say.
Researchers at Johns Hopkins Medicine have discovered a chemical alteration in a single human gene linked to stress reactions that, if confirmed in larger studies, could allow for a blood test to predict suicide risk.
The discovery suggests that changes in a gene involved in the function of the brain's response to stress hormones plays a significant role in turning what might otherwise be an unremarkable reaction to the strain of everyday life into suicidal thoughts and behaviours.
"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," said study leader Zachary Kaminsky, an assistant professor of psychiatry and behavioural sciences at the 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," Kaminsky said.
Kaminsky and his colleagues focused on a genetic mutation in a gene known as SKA2.
By looking at brain samples from mentally ill and healthy people, researchers found that in samples from people who had died by suicide, levels of SKA2 were significantly reduced.
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 same study subjects who had killed themselves. The higher levels of methylation among suicide decedents were then replicated in two independent brain cohorts.
In another part of the study, the researchers tested three different sets of blood samples, the largest one involving 325 participants in the Johns Hopkins Center for Prevention Research Study found similar methylation increases at SKA2 in individuals with suicidal thoughts or attempts.
They then designed a model analysis that predicted which of the participants were experiencing suicidal thoughts or had attempted suicide with 80 per cent certainty.
Those with more severe risk of suicide were predicted with 90 per cent accuracy. In the youngest data set, they were able to identify with 96 per cent accuracy whether or not a participant had attempted suicide, based on blood test results.
Kaminsky said a test based on these findings might best be used to predict future suicide attempts in those who are ill, to restrict lethal means or methods among those a risk, or to make decisions regarding the intensity of intervention approaches.
The study was published in The American Journal of Psychiatry.
