This means that, in theory, suicide should be preventable if we can deliver the right treatment to people who have these psychiatric illnesses.

Unfortunately, it’s hard to know which treatments are most effective at preventing suicides because most studies of mental health interventions specifically exclude suicidal subjects. (This is because ethics boards are typically reluctant to allow people at this kind of risk to receive a placebo treatment.) One notable exception is a Johns Hopkins study of a group of Danish patients showing that deaths by suicide were about a quarter lower in people who had six to 10 talk therapy sessions.

There is good reason to believe that if more people had access to such simple but high-quality treatments, we would see a drop in suicide. (Skeptics will point out, correctly, that suicide rates have been rising despite a growing number of people taking antidepressants. I would respond that there is more to the effective treatment of depression than just taking antidepressants.)

Still, a big challenge is that suicidal people often conceal their symptoms. Although Ms. Spade’s husband, for example, knew that she struggled with a mood disorder, he said: “There was no indication and no warning that she would do this. It was a complete shock.”

Many people are also reluctant to ask friends and loved ones who seem distressed whether they are thinking about suicide, for fear that somehow inquiring about it could incite suicide. But research shows otherwise.

Dr. Madelyn Gould, a psychology professor at Columbia, and colleagues screened a group of high school students about their moods. Subjects exposed to questions about suicidal feelings or thoughts were no more likely to report thinking about suicide after the survey than those who were not asked these questions. The implication is that we should not be afraid to ask people we are concerned about if they are feeling suicidal.

In fact, we need to talk more openly about suicide, to help people see it as the treatable medical scourge that it is.