Two New Ways of Predicting Suicide

Psychologists at Harvard developed two powerful tests that can predict more accurately patients' risk of attempting suicide.

Harvard Professor of Psychology Matthew K. Nock and his colleagues present the tests in two papers, published in the current Journal of Abnormal Psychology and in Psychological Science. The innovation of these tests is that they allow the identification of two behavioral markers: the reaction to stimuli related to suicide and how much the subjects associate death or suicide with themselves.

Both tests can be passed on a computer within a few minutes and the results are very precise. Instead of relying on patients' self-reporting, which can often prove misleading as they usually hide suicide plans, doctors can find out if subjects are thinking about suicide and if they will attempt it in the near future.

“Experts have long sought a clear behavioral marker of suicide risk," says professor Nock. “The current approach, based on self-reporting, leads to predictions that are scarcely better than chance, since suicidal patients are often motivated to conceal or misrepresent their mental state. We sought to develop more sophisticated, objective measures of how psychiatric patients are thinking about suicide. Our work provides two important new tools clinicians can use in deciding how to treat potentially suicidal patients.”

The first study passed a modified Stroop test to 124 patients from a psychiatric emergency department. The test measured speed in articulating the color of words showing up on the screen and showed that suicidal patients payed more attention to suicide-related words.

Christine B. Cha, co-author and a doctoral student in psychology at Harvard says that “Suicide Stroop scores predicted six-month follow-up suicide attempts above and beyond well-known risk factors such as a history of suicide attempts, patients' reported likelihood of attempt, and clinicians' predictions regarding patients' likelihood of attempt.”

The second study was based on the Implicit Association Test developed by Mahzarin R. Banaji, a Harvard psychologist. It used reaction times to semantic stimuli and measured automatic mental associations in 157 subjects. Participants were shown pairs of words on a screen and their response speed revealed the way they were unconsciously associating terms.

Nock and his colleagues concluded that people that made strong associations between self and death/suicide presented six times greater risk of attempting suicide within the next six months than those associating self and life.

“These findings suggest that a person's implicit cognition may guide which behavior he or she chooses to cope with extreme distress,” Nock added. “More specifically, an implicit association with death/suicide may represent one of the final steps in the pathway to suicide.”