More than 40,000 Americans commit suicide each year. A major challenge for mental health professionals is trying to anticipate when someone is truly at risk.

Many depressed people talk about suicidal thoughts but never intend to act on them. It’s critical to identify those who may do so.

Scientists at Indiana University School of Medicine developed a system of blood tests and an application that predicts suicidal thinking or attempts with 90 percent accuracy. The app presents questions about mood, energy level, and various life issues, yet avoids asking about suicidal thinking directly.

In their study, published in the journal Molecular Psychiatry, the researchers presented their blood test and app results of more than 200 high-risk patients with psychiatric illnesses.

More studies are needed to see whether this approach can be applied to larger at-risk populations.