One person dies by suicide every 13 minutes in America, resulting in about 38,000 deaths each year. While most people who commit suicide suffer from depression or other mental illnesses, the vast majority of depressed people will never attempt to kill themselves. This leaves psychiatrists and other health professionals with the difficult task of figuring out which patients are most at risk.
Now, new research suggests that certain blood biomarkers, in conjunction with a questionnaire, can identify with more than 90 percent accuracy patients who will suffer suicidal ideation (thoughts about how to kill oneself) in the following year. Building on previous research identifying blood biomarkers for psychiatric illness, it holds promise for both patients and doctors.
“We want to identify people who are at risk early on, when simple interventions, lifestyle innovations—reducing stress, getting more sleep, treatment, medications—can change the trajectory for the positive before it spirals into a tragedy,” says Alexander Niculescu of Indiana University School of Medicine, the lead researcher on the study, recently published in the journal Molecular Psychiatry.
The study began with a cohort of 217 male patients currently receiving psychiatric treatment. The researchers took multiple blood samples from each patient over time, attempting to “catch” samples during times when patients were not feeling suicidal at all and when they were feeling very suicidal. They then compared the blood samples from reported suicidal-feeling times and non-suicidal-feeling times, identifying changes in gene expression. They compared these markers with markers present in the blood of 26 suicide victims from the coroner’s office in Indianapolis and markers identified in prior studies as being present in suicidal patients. They then narrowed the markers to the 11 most significant.
The researchers then developed a questionnaire assessing suicide risk, which they made into an app. The app didn’t directly ask patients if they were considering suicide. “People who are truly suicidal often choose not to share that information with their clinician because they don’t want to be stopped,” Niculescu says. Instead, the app identified various known social, cultural, mental and environmental risk factors for suicide, such as a family history of suicide, a history of abuse, serious physical illness, recent loss of a loved one and addiction.
The team gave the app questionnaire and the biomarker tests to a new group of 108 psychiatric patients. These patients had previously been diagnosed with major depressive disorder, bipolar disorder, schizophrenia or schizoaffective disorder. The researchers followed them over a period of a year to see if they developed suicidal thoughts or were hospitalized for suicide attempts.
The results were fairly dramatic. The biomarker-app combination was able to predict suicidal ideation with 92 percent accuracy. For patients with bipolar disorder, the combo’s predictive powers were even stronger: it predicted suicidal ideation with 98 percent accuracy and hospitalization with 94 percent. Separately, the app and the blood test were much less effective for predicting the likelihood of suicidal thoughts: about 80 percent and 70 percent, respectively.
“The app assesses the context in which the biomarkers are elevated,” Niculescu says. “If you have the biomarkers in the context of having these other risk factors, then you’re at very high risk—that’s what our study is showing.”
It’s not entirely clear why gene expression changes along with mental state. Researchers theorize that these are responses to stress and anxiety, themselves predictors of suicide.
Niculescu sees these biomarkers as part of a building movement to make psychiatry more biologically based. “[The research] in all likelihood will translate to clinical applications over the next five years, which will bring psychiatry more on par with other medical specialties,” he says. “You’ll have a risk test, just like in cardiology, just a little bit more indirect.”
In the short term, Niculescu sees the biomarkers and the app as being useful in an acute care setting, like an emergency room, where a doctor needs to make a decision about who to admit and who to allow to go home in cases of injuries and overdoses that may or may not have been intentional. In the longer term, he hopes the test could be used to prevent these crises before they start.
One limitation to the study is that all the test subjects were men. However, a second study looking at women has already been done. Though it is yet unpublished, Niculescu says the results are “promising.”
It’s also unclear if the biomarker and app combo will be useful for people without severe mental health diagnoses; it’s not just people with major depression or schizophrenia who kill themselves. While some psychiatrists say the risks of false positives in the general population are too high, Niculescu says he’s “cautiously optimistic” it will work.