Could a blood test predict suicide risk?

Clues to whether a person is at risk for suicide could lie in a simple blood test, a new study suggests.

Chemical changes to a gene involved in the brain's response to stress hormones may help spur suicidal thoughts and behaviors, the study's authors explained. Spotting those changes in a blood sample might help alert doctors to a patient's risk for suicide, they said.

"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," study lead researcher Zachary Kaminsky, assistant professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine, said in a university news release.

"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," he said.

In the study, which was partially funded by the U.S. National Institute of Mental Health, the researchers analyzed genetic mutations in a gene known as SKA2. As the researchers explained, the SKA2 gene is expressed in a part of the brain that is responsible for blocking negative thoughts and controlling impulsive behavior. The gene is also essential for moving stress hormone receptors that suppress the release of the "stress hormone" cortisol throughout the brain.

The famous "risk factors" for suicide are helpful but can do little to tell you if self-destruction is imminent, because they refer to long-term statistical probabilities. In fact, most people with these risk factors will never attempt suicide. Nonetheless, you should memorize them for two reasons: first, they serve as red flags during your assessment of potentially suicidal patients, prompting you to dig more deeply for serious suicidal ideation; and second, they are important to document from a medico-legal standpoint (see related article in this issue).

The best way to memorize these risk factors is to use the famous "SAD PERSONS" mnemonic for the 10 major suicide risk factors (Psychosomatics 1983; 24:343-349). These include: Sex (more men complete suicides, more women attempt it), Age (elderly are at highest risk), Depression and bipolar disorder (each increases lifetime suicide risk 15-fold), Previous suicide attempt (strongest risk factor of all), Ethanol abuse (up to half of attempters used alcohol just before the attempt), Rational thinking loss (this refers to psychosis, but most studies to look at command hallucinations have found no significant association with an attempt), Social supports lacking, Organized plan, No spouse or child (especially for women, having a child decreases suicide risk), and Sickness (especially those leading to chronic pain and functional impairment).