We know from statistics that some groups are at greater risk for suicide than others--among them people with major depression, older men, residents of the eight western "intermountain" states, gay and lesbian teens, and people in certain high-stress professions, including doctors, lawyers and psychiatrists (see Suicide facts and figures).

But these numbers do little to explain what drives an individual to take his or her life, experts say.

"We're really very young in our understanding of this phenomenon," says psychologist Lanny Berman, PhD, executive director of the American Association of Suicidology and a suicide researcher since 1970. "We have a lot to learn about subtypes of people who complete suicide, the etiology of and pathway for their behavior, and why people with much the same dynamic picture take such different paths."

"We will never be able to make a single statement that this is what caused an individual's suicide," says Edward Dunne, PhD, who directs the clinic for gay and lesbian families at the Ackerman Institute for the Family in New York. "We've had 20 years of access to very good antidepressants, and there are lots and lots of people on them, but the suicide rate remains roughly the same"--more than 11 out of 100,000 Americans.

Suicide experts are, however, beginning to recognize common emotional threads that may underlie some suicides. Prominent among these, they say, are a perceived sense of isolation, a lack of personal attachments and a dearth of coping skills.

Moreover, mental disorders, particularly depression in some form, play a prominent role in more than 90 percent of all suicides, and may require significant biological and psychological treatment.

Take the example of an elderly man who has lost his spouse, says Berman. Besides grieving a profound loss, he may lack coping skills in areas once in his wife's purview, such as reaching out to friends or cooking for himself. Facing a vacuum in these life arenas further fuels his grief and loneliness and challenges him to learn new skills that he's not ready to handle. These combined losses and unmet needs may in turn activate an underlying depression that makes him feel helpless and eventually hopeless and suicidal.

Healthy coping, according to crisis theory, involves four dimensions: involvement in daily activities, a supportive community, physical well-being and good quality of life, says Frank Campbell, a social worker who heads the Baton Rouge Crisis Intervention Center in Baton Rouge, La. Suicide attempts, on the other hand, can be seen as maladaptive efforts to cope, he says. In the context of crisis theory, counseling for those at risk for suicide may therefore involve anything from strengthening clients' relationships with supportive people to encouraging them to develop engaging hobbies.

Meanwhile, the area cries for more research on interventions, Berman adds. "We know too little about what works, especially with different types of suicidal people," he says.

The available research tends to be on short-term behavioral interventions. But studies show that suicidal people are likely to become suicidal again at other stressful life points, so what's really needed is more study of long-term interventions or short-term therapies with "booster shots"--a current void in the literature.

Even if clinicians have employed the best available knowledge and the keenest intuition, it's possible that a person may take his or her life without warning. A young client Campbell had seen years before and with whom he was in regular touch gave no outward indication that he was on the brink of suicide. In fact, not long before he killed himself, he reported to Campbell that he was feeling good about life and enjoying his life in a new city.

"I don't think I missed anything, and I don't think he hid anything from me," Campbell says. "I think he entered into a psychotic depression and felt he was losing support."

Incidents such as these underscore the ultimate mystery that is suicide, Dunne adds. "I've gotten much more humble in my understanding of it," he says. "No matter what happens, there's always an element of the unknown."

Tori DeAngelis is a writer in Syracuse, N.Y.