A tragedy in every way. Photographer: bugphai via Getty Images
A tragedy in every way. Photographer: bugphai via Getty Images

Robin Williams's death has brought welcome attention to the very real problem of suicide in the U.S. From 2000 to 2011, suicides increased to 12.3 per 100,000 people from 10.4. Deaths by suicide now exceed those from motor-vehicle accidents.

This is not, as you might think, a problem occurring disproportionately among teenagers or the very old. The people most prone to taking their own lives are those 45 to 59 years old (Robin Williams was 63). Suicides among those in their 50s have been rising especially fast: In 1999, the rate for people in that decade was 13 per 100,000 people; by 2010, it had risen almost by half, to 20 per 100,000.

What puzzles researchers even more is that men commit suicide more often than women do -- about four times as often -- even though most studies find that women are twice as likely to be depressed and also more likely to have suicidal thoughts. This discrepancy suggests an eightfold difference between the chances that a depressed man and a depressed woman will succeed in committing suicide.

Part of this may be a mirage, because depression in men can manifest itself in ways that don't always involve crying, sadness or other traditional symptoms, according to research by Lisa Martin and Harold Neighbors of the University of Michigan and Derek Griffith of Vanderbilt University. The depressed men in their study were more likely to report "anger attacks/aggression, irritability, substance abuse and risk-taking behaviors.” When these alternative indicators of depression are included as symptoms, depression rates among men measure about the same as those among women.

So if men aren’t any more depressed than women, why do Centers for Disease Control and Prevention data show that women are more likely to have suicidal thoughts? The answer here is that the difference is not great enough to matter. In 2008 and 2009, 3.9 percent of women had suicidal thoughts, compared with 3.5 percent of men -- not a statistically significant difference. More important, the same data show no difference between men and women in the study who actually made a suicide plan (1 percent of both sexes).

Which brings us to the heart of the puzzle. When men attempt suicide, they tend to use methods that ensure death -- either with firearms or by suffocation (including hanging). Women, on the other hand, often try to poison themselves. In 2010, 77 percent of suicides among men aged 35 to 64 involved firearms or hanging, compared with 49 percent of suicides among women. More than 40 percent of suicides among women, but only 15 percent among men, involved poisoning.

Survival rates are substantially higher for those who try poisoning themselves than for those who try guns or hanging; poisoning isn't as likely to cause immediate death, so the chances are better the person can be resuscitated. (The male-female difference in methods is true outside the U.S. as well. In one cross-European study of suicides, more than 60 percent of males, but only about 40 percent of females, used firearms or hanging.)

What remains unknown is why men choose more deadly strategies. Is it because they are more comfortable with guns and other lethal means of killing? Or are they just more determined to end their lives? Given the rising incidence of suicide, these questions deserve much more attention.

To contact the writer of this article: Peter Orszag at orszagbloomberg@gmail.com.

To contact the editor responsible for this article: Mary Duenwald at mduenwald@bloomberg.net.