Illustrated By Ly Ngo.
The 10th leading cause of death in the U.S. may be the hardest one to talk about. The Centers for Disease Control and Prevention reports that suicide filled that slot in 2010, claiming nearly 40,000 lives that year; on average, a person took his or her own life every 14 minutes. The problem is even more pronounced among younger generations: It’s the third leading cause of death among people ages 15-24, and the second leading cause in the 25-34 age group.
Past suicide prevention efforts have focused on identifying warning signs, but now, researchers at Johns Hopkins are onto a more scientific method for predicting who is at risk. Their findings, published yesterday in the American Journal of Psychiatry, center around a single human gene — called SKA2 — that dictates reactions to stress. By studying postmortem brain samples from both healthy and mentally-ill individuals, researchers discovered that levels of SKA2 in the brains of people who had committed suicide were significantly lower than SKA2 levels in the brains of healthy people. Expressed in the brain’s prefrontal cortex, SKA2 curbs impulses and negative thoughts by acting as air traffic control for stress hormone receptors, directing these receptors into cells’ nuclei. There, the receptors are able to regulate the release of cortisol, the body's stress hormone.
In some subjects with low SKA2 levels, the researchers found a mutation that added chemicals known as “methyl groups” which limits the gene's ability to control cortisol. When SKA2 can’t do its job, cortisol levels — and, with them, negative thoughts and emotions — skyrocket. Sure enough, the researchers measured the highest levels of methylation in subjects who had committed suicide.
To confirm their results, researchers tested blood samples from hundreds of (living) participants — and again found that individuals with suicidal thoughts and/or attempts showed the highest levels of methylation. The research team then created a model blood analysis that was able to predict whether people had suicidal thoughts or impulses with 80% accuracy (90% accuracy among those with severe risk). And, among the study’s youngest subjects, researchers predicted whether or not an individual had attempted suicide in the past with a stunning 96% rate of accuracy.
The study opens the door to development of a standardized blood test to assess individuals’ suicide risks. Of course, such a test wouldn’t supplant “traditional” methods of looking for warning signs. But, as researchers point out, it could be helpful in psychiatric settings, or in monitoring military members who have returned from active duty — a valuable diagnostic tool for providing those at risk with the best possible care. What's more, this research highlights the neurological underpinnings of depression and suicide, hopefully further de-stigmatizing these problems as we better understand the science behind them.