Kim Tingley / The New York Times

For reasons that have eluded people forever, many of us seem bent on our own destruction. Recently more human beings have been dying by suicide annually than by murder and warfare combined. Despite the progress made by science, medicine and mental-health care in the 20th century — the sequencing of our genome, the advent of antidepressants, the reconsidering of asylums and lobotomies — nothing has been able to drive down the suicide rate in the general population. In the United States, it has held relatively steady since 1942. Worldwide, roughly one million people kill themselves every year.

Last year, more active-duty U.S. soldiers killed themselves than died in combat; their suicide rate has been rising since 2004. Last month, the Centers for Disease Control and Prevention announced that the suicide rate among middle-aged Americans has climbed nearly 30 percent since 1999. In response to that widely reported increase, Thomas Frieden, the director of the CDC, appeared on “PBS NewsHour” and advised viewers to cultivate a social life, get treatment for mental-health problems, exercise and consume alcohol in moderation. In essence, he was saying, keep out of those demographic groups with high suicide rates, which include people with a mental illness like a mood disorder, social isolates and substance abusers, as well as elderly white males, young American Indians, residents of the Southwest, adults who suffered abuse as children and people who have guns handy.

But most individuals in every one of those groups never have suicidal thoughts — even fewer act on them — and no data exist to explain the difference between those who will and those who won’t. We also have no way of guessing when — in the next hour? in the next decade? — known risk factors might lead to an attempt. Our understanding of how suicidal thinking progresses, or how to spot and halt it, is little better now than it was two-and-a-half centuries ago, when we first began to consider suicide a medical rather than philosophical problem and physicians prescribed, to ward it off, buckets of cold water thrown at the head.

“We’ve never gone out and observed as an ecologist would, or a biologist would go out and observe, the thing you’re interested in for hours and hours and hours, and then understand its basic properties and then work from that,” Matthew Nock, the director of Harvard University’s Laboratory for Clinical and Developmental Research, told me. “We’ve never done it.”

It was a bright December morning, and we were in his office on the 12th floor of the building that houses the school’s psychology department, a white cement slab jutting above its neighbors like a watchtower. Below, Cambridge looked like a toy city — gabled roofs and steeples, a ribbon of road, windshields winking in the sun. Nock had just held a meeting with four members of his research team — he in his swivel chair, they on his sofa — about several of the studies they were running. His blue eyes matched his diamond-plaid sweater, and he was neatly shorn and upbeat. He seemed more like a youth soccer coach, which he is on Saturday mornings for his son’s first-grade team, than an expert in self-destruction.

At the meeting, I listened to Nock and his researchers discuss a study they were collaborating on with the Army. They were calling soldiers who had recently attempted suicide and asking them to explain what they had done and why. Nock hoped that sifting through the interview transcripts for repeated phrasings or themes might suggest predictive patterns that he could design tests to catch. A clinical psychologist, he had trained each of his researchers how to ask specific questions over the telephone. Adam Jaroszewski, an earnest 29-year-old in tortoiseshell glasses, told me that he had been nervous about calling subjects in the hospital, where they were still recovering, and probing them about why they tried to end their lives: Why that moment? Why that method? Could anything have happened to make them change their minds? Though the soldiers had volunteered to talk, Jaroszewski worried about the inflections of his voice: How could he put them at ease and sound caring and grateful for their participation without ceding his neutral scientific tone? Nock, he said, told him that what helped him find a balance between empathy and objectivity was picturing Columbo, the frumpy, polite, persistently quizzical TV detective played by Peter Falk. “Just try to be really, really curious,” Nock said.

That curiosity has made Nock, 39, one of the most original and influential suicide researchers in the world. In 2011, he received a MacArthur genius award for inventing new ways to investigate the hidden workings of a behavior that seems as impossible to untangle, empirically, as love or dreams.

Suicidal thinking

Trying to study what people are thinking before they try to kill themselves is like trying to examine a shadow with a flashlight: The minute you spotlight it, it disappears. Researchers can’t ethically induce suicidal thinking in the lab and watch it develop. Uniquely human, it can’t be observed in other species. And it is impossible to interview anyone who has died by suicide. To understand it, psychologists have most often employed two frustratingly imprecise methods: they have investigated the lives of people who have killed themselves, and any notes that may have been left behind, looking for clues to what their thinking might have been, or they have asked people who have attempted suicide to describe their thought processes — though their mental states may differ from those of people whose attempts were lethal and their recollections may be incomplete or inaccurate. Such investigative methods can generate useful statistics and hypotheses about how a suicidal impulse might start and how it travels from thought to action, but that’s not the same as objective evidence about how it unfolds in real time.

The inscrutability of suicide has not kept most psychologists who study it from theorizing about why people kill themselves. Nock, however, tends to approach the problem from a different angle. “I think it’s easy to generate explanations,” he said recently. “It’s much harder to test out these different explanations and see whether the data support them or not.” At first, the stress of combat seemed to be the obvious reason for the jump in military suicides — until researchers realized that the rate has also risen among soldiers who were never deployed. Public-health experts have speculated that the uptick in suicides among the middle-aged is linked to modern tensions like the troubled economy, the stress of caring for elderly parents and insolvent children, and unprecedented access to prescription drugs. Nock, conversely, tends to point to a jagged line showing the suicide rate for 45-to-64-year-olds over the past 30, rather than 10, years. The line tacks up, down, up — it tells a more complicated story. “My thought is that we’ve had theories of suicide for a long time and no data,” he said. “So we want to work from the other end.”

Indeed, Nock has started from scratch by searching for a way to precisely measure suicide risk. Three years ago, he and his team published a paper suggesting that they had found, for the first time, an objective test that could predict a psychiatric patient’s likelihood of a suicide attempt better than the patient or his clinician could. Nock is now running it and other tests on hundreds of people — those who have tried to kill themselves, those who have had suicidal thoughts and those who have not — to see how the initial scores differ from one group to another and whether those scores will end up having forecasted, beyond what current methods can, who will try to kill themselves in the future.

Each data point Nock collects moves him one step closer to his ultimate goal: to be able to give people a series of tests that could tell them — and their psychiatrists or primary care physicians or school nurses — how high their risk of suicide is at any given moment, much the way cardiologists can use blood-pressure and cholesterol readings combined with weight and height to calculate a person’s risk of heart disease.

Each data point is also a person whose impossibly complex conscious and unconscious thoughts — about who they are, what they want, what’s possible and tolerable — highlight both why such tests are needed and why it is so surprising that they might actually work.

Melissa’s story

When Melissa was growing up in Southern California, her playmates included six imaginary princesses. One of them was always getting captured, and Melissa, a princess herself, would save her, she told me. We were in a tea shop on a February afternoon in Harvard Square, where the clattering dishes, the hiss of steaming milk and the wash of voices cocooned our conversation the way she preferred. Melissa, who asked to be identified only by her middle name, wore a thin, white-checkered coat. She was 18, petite and pale, with faint freckles and auburn hair collected in a silver clip. Last November, she tried to kill herself in her college dorm room with an overdose of pills. Now, three months later, she had completed a residential treatment program at McLean Hospital in Belmont, Mass., and was living in a transitional house in Cambridge for psychiatric patients. She was taking classes at a local extension school; to return to her former college, a liberal-arts academy in another state, she would need to reapply. I first met Melissa in Nock’s lab and was impressed by her cinematic memory. But even for her, trying to recreate the progress of her suicidal thoughts was like trying to trace a breaking wave back out to the ocean. Her parents, her doctors and even Melissa herself had not known the wave was coming until it hit. Now all of them were hoping to turn back future danger without knowing exactly what to look for.

In seventh grade, Melissa said, she sometimes wrote “goodbye notes” in her head in the shower. That year, she started feeling excluded by her friends, and because she was later than other girls to hit her growth spurt, she said, she looked like an outsider too. The notions she had about ending her life were mostly fantasy. “It was never something that I talked about, but it was always kind of there,” she said. She hadn’t considered herself “brave enough” to really do it, though she now thought “brave” was a weird word to use.

Melissa talked about her high-school years with animation, doing goofy voices to narrate the naïve thoughts of her younger self. She recalled mean messages her classmates had posted about her on a popular online forum, even as she sympathized with what she saw as their desire to fit in. Early on, she started drinking regularly and smoking pot. She starved herself. She fought with her parents. Her grades dropped. The summer after her sophomore year, Melissa told her parents that she felt suicidal and needed to go to a hospital; doctors there held her for five days and prescribed medication that her father, a neurobiologist, and her mother, a biochemist, refused because they felt it was far too strong for her, her mother told me. Eventually afraid to leave her alone for even a few minutes, they enrolled her in an inpatient program for substance abuse and mental illness. Melissa felt the counselors there punished her for her behavior instead of helping her learn how to change it, and they held her beyond the month she expected. “They said I was resisting treatment,” she said. “Really the only thing that it taught me was that I have to get myself out of here. To leave, I had to explain why I was manipulative, passive-aggressive, how I relate to boys by expressing my sexuality.” These assumptions offended her, and she didn’t believe they were true. Ultimately, however, she told her doctors what she thought they wanted to hear, and they let her go.

Melissa saw a psychiatrist, who prescribed medication for depression and anxiety, and she went through several outpatient programs with better results. She transferred to a new school for her junior year, which eased her social stress; she was a competitive athlete, acted in plays and raised money for impoverished children in India that she delivered in person. She was accepted by her first-choice college. The summer before she left home, at a ceremony at a treatment center, she told me, the mother of another girl said to her, “I don’t understand why you would be here in the first place, because it seems like you have everything figured out.” Outwardly she accepted the remark as a compliment, though it startled her to realize that she seemed to have everyone fooled. “At that exact point in time,” she said, “I was thinking about anything except being alive.”

Her parents, worried, stipulated that they would pay her college tuition only if she attended weekly therapy sessions at the school’s health-services center, which would report missed attendance to them. But Melissa wanted to start over. She skipped sessions and stopped taking her medication — despite the potentially dangerous side effects of quitting abruptly — saving the pills in a Ziplock instead. Her mother told me she flew out to check on her, but Melissa didn’t want to see her. She was 18 by then and in charge of her own health care. At the tea shop, Melissa described how she decorated her new dorm room, putting up a Harry Potter poster she brought from home and making the bed with blue sheets her mother bought for her when she was 13 and scared to go to sleep. She found friends, began drinking and doing drugs again and fell behind in her classes. About a month into the semester, she said, a painful episode between her and a boy she was seeing became campus gossip, making her feel heartbroken and exposed. She couldn’t say exactly how or when she formed a plan to use the pills she had saved as “an emergency-exit measure.”

She tugged at a pink hair tie on her wrist. “I’m having a hard time explaining this,” she told me. “It wasn’t one specific moment. It was just everything.”

I asked her if the therapists she saw ever questioned whether she had suicidal thoughts. “They always asked,” she said. “And, the answer I always gave was, ‘Yes, I had thoughts, and ... it was nothing I would act on.’ It was sort of a robot answer, and it wasn’t really true, but I wasn’t in a position that I could say, ‘No, I love my life,’ and I wasn’t in a position where I could say, ‘Yes, I spend my subway rides planning out my goodbye note.’ ”

Melissa found it hard to say why she tried to kill herself when she did — how that night differed from others when she had felt wounded or sad. “Everything just kind of hit me all at once,” she said. “I was behind in my classes. I felt like my friends were embarrassed by me. And, I don’t know, I just felt like I had screwed up my life so badly that this was the only way out.”

Nock’s story

Nock didn’t plan to devote his career to researching self-harm. The son of an auto mechanic, he grew up pumping gas and learning to fix cars at the service station his parents own in Basking Ridge, N.J., while also taking other odd jobs: tuxedo-rental clerk, ice-rink guard, windshield repairer. He was the first member of his family to graduate from college and expected to use his degree in psychology to become a clinician and work with patients. But the more time he spent with people who hurt themselves, the more he worried about treating their behavior. His first internship, while an undergrad at Boston University, was in a psychiatric unit for violent patients prone to severe self-injury: one man pulled out his eyeball, another arrived with deep gashes in his arms. Nock, who rarely mentioned his own feelings even when I asked him personal questions, said he grew close to the youngest patient on the unit, a man about his age. “When he was in treatment, moodwise he was pretty stable, pretty happy guy, pretty upbeat guy,” Nock said. “We’d talk a lot about hip-hop and soccer.” When he was released, around the time Nock’s internship was ending, he killed himself. He was the first person Nock knew who died by suicide, and Nock had not foreseen it. He went on to get a doctorate in psychology from Yale, and instead of joining a clinical practice, he turned to academia and research.

Root causes

Nothing in medical literature suggests a reliable method for accurately identifying suicidal patients. The earliest known reference to suicide is a poem, written on papyrus in Egypt 4,000 years ago.

Suicidal behavior also appears to run in families, suggesting it has biological roots. “We think that there are many genes — there might be hundreds, there might be thousands, each of which might contribute a tiny amount individually” to heightened risk, says Jordan Smoller, a psychiatric geneticist at Mass General who has collaborated with Nock. Gustavo Turecki, the director of the McGill Group for Suicide Studies, has also shown that one major risk factor linked to suicide, having suffered abuse in childhood, can cause epigenetic changes in the receptors of brain cells that regulate the stress hormone cortisol, leaving the brain in a chemical state of increased alertness that causes a person to overreact to stress. “Our emotions are all somewhere coded in our brains,” Turecki told me, and identifying what mechanisms drive suicide could one day enable scientists to tailor drug therapies to reduce risk. Right now, though, Nock’s tests appear to offer our best hope for a diagnostic tool that could work on anyone, no matter what complex social and biological factors are prompting suicidal thoughts. They also offer a way of seeing how such thinking operates, which could help us understand why it happens.

In 2003, during his first year teaching at Harvard, Nock approached his colleague Mahzarin Banaji with a proposal. Banaji had helped develop the Implicit Association Test, which was introduced to social psychology five years earlier and has become famous for its ability to measure biases that subjects either don’t care to acknowledge or don’t realize they have on topics like race, sexuality, gender and age. Nock wondered if the I.A.T. could be configured to measure people’s bias for and against being alive and being dead, and Banaji thought it was worth a try. They experimented with several versions in Nock’s lab and at the psychiatric-emergency department at Massachusetts General Hospital. Then they put their best one on a laptop and offered it to Mass General patients, many of whom had recently threatened or attempted suicide; 157 agreed to take it.

The Mass General patients and their clinicians rated on separate scales how likely they thought they were to try to kill themselves in the future. When researchers checked on each patient six months later, they discovered that, as expected, clinicians had fared no better than 50-50 in their predictions. Patients themselves, it turned out, were only slightly more accurate. The I.A.T., to everyone’s surprise, bested them both. The I.A.T., it seemed, was picking up a heightened signal of suicidal tendencies that the most commonly used method for assessing risk — a clinical interview — had been powerless to detect.

A major investment of money and manpower from the Army is set to revolutionize the scope of collecting data on suicidal behavior. Nock and his team are participating in the Army Study to Assess Risk and Resilience in Servicemembers, which got under way in 2009 and is the largest, most comprehensive investigation of suicide ever undertaken.

“Right now, we ask people if they’re suicidal,” Nock said. “And if they say yes, we give them medication to try and make them less depressed or less anxious or less psychotic or to have a more stable mood. And then we talk to them. We do talk therapy. And, essentially, talk them into not being suicidal anymore. And this overall as a strategy for many people does not seem to be curative.” But if doctors could see which patients are suicidal at a given moment, they might be able to retrain their self-destructive thinking based on their test scores. If, as the I.A.T. seems to suggest, associating yourself more with dying than with living increases your risk for suicide, breaking that association might decrease it.